Boat Builder Central - Builder Forums

Posted: **Fri Aug 20, 2021 12:52 pm**

First off I'd like to compliment Jeff and Reid on their professionalism and accommodation of storing my materials until I was able to pick them up (months) after ordering them. I work in the medical field and to say the least, it's been insane over this past year and a half.
Never once did I ever receive a phone call, text message, or email questioning when would be there to get it. Even after me canceling a pickup date on more than one occasion. GREAT GUYS!!

On to my build lol. My father and I were finally able to have a free day to get down to Fort Pierce to pick my hull core material. I've had these plans for over two years now and to be honest, have gone back and forth with myself numerous times on whether to build what I want or to just buy a bay boat. Obviously, I've decided to build one. I will be using all composite material for this build, divinycell for the hull core, bulkheads and stringer, Glass Reinforced Polyurethane Foam for the transom and hatch covers, and lastly honeycomb for the deck. I have yet to find a Phantom build that is all-composite, If one is out there and has a build thread I'd love to see/learn from it. My plan is to updated this thread as much as I possibly can throughout this build. I'd like to also start a youtube build thread for this build as there is limited information regarding foam core boat building out there (Could be a sign right lol). If anyone on here has any recommendations for a video recorder I'm all ears. So to start off with I have two questions I'd greatly appreciate input on.

1. Glass layup- I have the glass layup that came with the plans which call for marine ply. I obviously cannot use the same layup for foam. I spoke with a local boat builder who builds foam core hulls, he recommended that I use (3) layers 1708 biaxial exterior and (2) layers interior prior to setting stringers. He advised this layup due to the size HP 250-300 that I'll be using to power the boat. Again any input would be appreciated.

2. Reverse chines- I will be adding reverse chines to the hull. I will be building this hull from a jig and am considering building them into the jig as opposed to adding them once the hull is built and glassed. My concern with "adding" them is the chance they could separate from the hull at some point.

Again thanks for any input. I'm excited to finally start this build with my father and learn from all the experienced builders on here.

Posted: **Fri Aug 20, 2021 3:26 pm**

Looking forward to seeing the build come together!

Posted: **Fri Aug 20, 2021 4:57 pm**

Since you bought everything from BBC Jacques will give you the proper lay up of the fiberglass, please give the office a call so they can get Jacques working on it for you. Since he is the designer you get the correct lay up. He may have already done it for some one else.

Tom

Posted: **Fri Aug 20, 2021 6:41 pm**

From the designer:
I was out of two for a couple days and could not reply earlier.
Please, do not get the lamination schedule from a friend or neighbor, get them from me, the designer.
There are several Phantoms built in foam sandwich and some hybrid. The very first one was around 1994, a PH18 that used Airex.
I calculated the specs for the PH22 years ago, was that not for you?
If not, I will check my files and we can discuss that next week. We just unloaded our suitcases, I'll check all that over the week-end.
We will also discuss the reverse chines.

Posted: **Fri Aug 20, 2021 8:21 pm**

I am not a naval architect, but your layup is not great.

Let me explain.

You have 5 layers of csm in the schedule. Those layers each add about 6-8 ounces of glass and resin that offers very little to the hull strength and offer only stiffness.

The weight per yard of the layup at 7 oz average mat and 17 is 24•5 or 120 ounces resin and 120 ounces glass. Or 240 ounces per yard with 70 ounces contribution almost no strength. 70/240 is about 29% no strength!!! Do NOT.

Also, the tow direction of all these layers is the same. Another error, imo. A layer or two of uni would make a lot of sense.

Anyhow, please understand, I am only wise by my reading and own personal work..I would recommend a far different layup. The csm has a place if you are gelcoating. That should also be noted in a lam sched.

Anyhow, 6 layers of db1700 is 204 ounces and probably stronger, so please pay attention to JM. He may spec some xx08 glass for thickness, but really I am not a fan of 5 layers of it..

Posted: **Fri Aug 20, 2021 8:32 pm**

On the issue of 'reverse' chines. I would think you'd need to pay a designer for that customization and it could go wrong some not tank modeled.

While largely out of my league, I can offer my thoughts.

They can certainly be built in, but glass only lays on curves. Your boat will be built upside down. A reverse chine would be cut into the jigs and foam laid therein. Then you'd glass the thing, probably rev chine on its own. Then you'd glass the hull overlapping the reverse. And you'd have on heluva fairing mess. And that is how a male plug for a mould is built! Then, after glassing, do some research and see if they have to have sharp edges. I believe they do or they will create drag. And so, more hand redesigning of the edges with fairing compounds. This is also required of all transoms on powerboats, btw.

Anyhow, I'd estimate about an extra three days work modifying, glassing and fairing for each reverse chine. Probably a bit light cuz each two days of fairing is usually one fill/sand cycle and you need say 3 or about 6 days...

All the best. Good luck. fg

Posted: **Sat Aug 21, 2021 6:45 am**

I put chine flats on my boat by filling behind a plywood dam, then fairing. I then glued some UHMWPE to the chines by flame treating and WEST Gflex. It was a fair bit of extra work, but I can't see any other way to get a sharp chine.

Probably your boat builder friend uses polyester or vinylester. The mat in the 1708 helps with bonding between layers. I would assume that the foam core version uses epoxy, in which case the bonding properties of mat are of no real concern. It may be advisable as a cheaper way to build thickness, wait for the designer to give the specs.

Posted: **Sat Aug 21, 2021 3:06 pm**

jacquesmm wrote: ↑Fri Aug 20, 2021 6:41 pm From the designer:
I was out of two for a couple days and could not reply earlier.
Please, do not get the lamination schedule from a friend or neighbor, get them from me, the designer.
There are several Phantoms built in foam sandwich and some hybrid. The very first one was around 1994, a PH18 that used Airex.
I calculated the specs for the PH22 years ago, was that not for you?
If not, I will check my files and we can discuss that next week. We just unloaded our suitcases, I'll check all that over the week-end.
We will also discuss the reverse chines.

This was not for me. Please take your time as I will not be ready for glassing for a couple of months. Also is there a build thread on the PH18 foam core build you mentioned?

Fallguy* Thank you for your advice. I will definitely build to what Jac advises. I was only mentioning the local guys' recommendations for feedback.

Onewaytraffic* I believe you're correct with the polyester or vinylester as he uses a gelcoat finish.

Posted: **Mon Aug 23, 2021 3:05 pm**

Lots to read since this week-end but I'll work on it. I was busy on another project.
I general, I agree with Fallguy's and Onewaytraffic remarks. Your boatbuilder friend was probably thinking polyester.
More later.

Posted: **Thu Aug 26, 2021 9:13 am**

Seems like a fun project. Youtube videos would be great as these days too much stuff gets lost to the facebook/instagram knowledge blackhole. don’t have to be the best edits, anything is great.

Posted: **Thu Sep 09, 2021 12:38 pm**

jacquesmm wrote: ↑Fri Aug 20, 2021 6:41 pm From the designer:
I was out of two for a couple days and could not reply earlier.
Please, do not get the lamination schedule from a friend or neighbor, get them from me, the designer.
There are several Phantoms built in foam sandwich and some hybrid. The very first one was around 1994, a PH18 that used Airex.
I calculated the specs for the PH22 years ago, was that not for you?
If not, I will check my files and we can discuss that next week. We just unloaded our suitcases, I'll check all that over the week-end.
We will also discuss the reverse chines.

Jac, have you had a chance to look for the lamination schedule for the PH22 foam core yet? Thanks.

Posted: **Thu Sep 09, 2021 3:02 pm**

I did not forget but put it on the back burner.
It's one thing to specify Divynicell H80 for a light boat like the FS18 but the bottom of a low deadrise 22 footer going 45 mph needs top of the line core and different laminating specs.
I am worried about your choice of a 250 HP. The slamming loads are a function of the square of the speed and that boat will be very fast with a 250. This is a flats boat hull, there will be more slamming than in a deeper vee like the CS23/25..
30 years ago, we did build an excellent foam cored PH18 that I tested for a few months going 50 mph but the bottom was plywood cored, only the bottom and the hull weight was 550 lbs. The idea was to avoid shear failure in the bottom.

I have specs for a number of foam cored planing boat bottoms up to 45' but those are built professionally.
There are two differences: the type of material (core and resin) and the "hinges". What I call the hinges are the chine and the keel. The very stiff side and bottom panels will want to flex along those lines and that is where we need to make a transition from core to single skin about 6"wide. If not, the core may fail in shear along those hinges.
You will need Corecell A in a high performance resin like the Silver Tip post cured or even Phase II.
The keel and chines must be made with a single skin transition. Those parts are difficult to build. When we plank the hull, all along the keel and chine, we replace the Corecell with a cheap throw away foam, When the outside skin is cured, boat flipped, we grind down the cheap foam, taper the good foam and build up a single skin along those "hinges".
All that is not necessary in most small boast for which I give foam core specs. Even a PH22 could be built with full cored chines and keel if you stayed below the max. 125 HP.

Another solution is to build the bottom panel in single skin fiberglass. That is easier but more costly. From the chine to the keel, you will plank with a sheet of heavy glass laminate: just like you would do with a plywood bottom. You could even use vinylester for that panel. After the boat is flipped, frame molds removed, you will build up the bottom to about 12 mm. It will cost more in material but it is a forgiving method, it's difficult to go wrong that way.

Consider the building method I describe above and the extra cost. If you still want it, I will write the specs. I may add a disclaimer.

Posted: **Thu Sep 09, 2021 4:55 pm**

ProfzX I did not realize you were looking to put a 250HP motor on your PH. Jacques recommends a 125HP for a reason as it will get it into the mid 40's. Doing a fiber glass version will make it lighter and increase its high speed. I calculated the PH with a 250 0n it and a 250 will give it a top speed of around 70mph. Jacques will have to heavily reinforce the bottom for speeds like that.

Posted: **Thu Sep 09, 2021 9:50 pm**

“You will need Corecell A in a high performance resin like the Silver Tip post cured or even Phase II.
The keel and chines must be made with a single skin transition. Those parts are difficult to build. When we plank the hull, all along the keel and chine, we replace the Corecell with a cheap throw away foam, When the outside skin is cured, boat flipped, we grind down the cheap foam, taper the good foam and build up a single skin along those” "hinges"

Then I should be able to build the entire hull by this method correct? I could use some “cheap” insulation foam board in place of the divinycell then grind it away and use my divinycell for stringers and bulkheads. No?

Posted: **Fri Sep 10, 2021 9:25 am**

ProfzrX wrote: ↑Thu Sep 09, 2021 9:50 pm

Then I should be able to build the entire hull by this method correct? I could use some “cheap” insulation foam board in place of the divinycell then grind it away and use my divinycell for stringers and bulkheads. No?

Yes but I still prefer the 2nd method: build the bottom as a single skin panel.

Posted: **Fri Sep 10, 2021 10:27 am**

jacquesmm wrote: ↑Fri Sep 10, 2021 9:25 am
ProfzrX wrote: ↑Thu Sep 09, 2021 9:50 pm

Then I should be able to build the entire hull by this method correct? I could use some “cheap” insulation foam board in place of the divinycell then grind it away and use my divinycell for stringers and bulkheads. No?
Yes but I still prefer the 2nd method: build the bottom as a single skin panel.

Can you please send me the lamination schedule for both methods?

This is honestly becoming a little frustrating. Prior to me even purchasing these plans I inquired on wether or not this build could be done as a foam core with the HP I was wanting. I was directed by Jeff to post this question on the forum and that you would respond. Which you did and at that time your response was it was doable but that you’d have to give a separate lamination schedule for both the hull bottom and also the transom. I followed thru with my $4k worth of foam purchase and now am being told that the only way it will be possible is if I use a different more expensive foam or not even use foam all together. Please forgive me for feeling a little hoodwinked here.

Posted: **Fri Sep 10, 2021 11:16 am**

Please see the max. HP listed for the PH22. That is where the problem is.
I don't remember stating that a foam core version for 250 HP was doable with plain Divynicell.

I can give specs for a foam cored hull rated for max. 125 HP, bottom cored but not for a 250 HP version.

The lamination schedule for the bottom and the sides are always different.

Posted: **Fri Sep 10, 2021 12:29 pm**

Thank you Jac. If you can please send me your recommended lamination schedule of both ways you mentioned so that I may equip the hull with a 250hp I’d appreciate it. Thanks.

Posted: **Fri Sep 10, 2021 1:58 pm**

ProfrsX Why do you keep insisting on a 250HP motor, are you build this for bass tournaments? Jacques just said he would give you the laminating schedule for a 125HP but not for a 250HP motor. Like I posted above a 250HP will give you speeds around 70mph, speeds that Jacques does not design his boats for as he does not want to take the liability for. If you want to add extra glass to the outer and inner hull and beef up the transom, that is your choice and your responsibility and your liability.

P

Posted: **Fri Sep 10, 2021 2:07 pm**

You need more than a schedule, you need some drawings showing the layup. I will scan pages from my books and foam data sheets.
In the mean time, please check this small PDF file, it explains what is involved;

http://ericgreeneassociates.com/images/ ... OSITES.pdf

I have an old printed version but that book is the bible of composite building. Skip over the details but see what I list below.

The construction methods that I mentioned start at page 180.

On page 269, look at figure 5-13, on the right side, it shows the transition to single skin.

Page 289 shows the overlaps that I specify.

I have more reference material with core manufacturers specifications for typical boats and will send you specs after this week-end.
Email to jacques@boatbuildercentral.com and I will reply with specs.

Posted: **Fri Sep 10, 2021 2:19 pm**

Thanks Tom. I think that we discussed that earlier when we met in NC but you are correct, I don't want to design boats for those speeds. Thirty years ago, I worked as an engineer for Cigarette and know what is involved. I also worked as engineering manager for Pursuit and until this day, that company builds excellent all composite boats but Cigarette or Pursuit never use cored bottoms. Cored bottoms are fine for smaller boats, perfect for quiet small units like the LM18, FS17 etc. It's great too for larger but slower boats like the LB26. I gave foam specs for the CS25 but have reservations about using Divynicell, Corecell is fine.

There is another problem with a flats boat at very high speed. The USCG has a bunch of requirements that my designs satisfy but if someone uses a larger motor and goes faster, that boat will fail what we call the slalom. The USCG/ABYC rules requires the boat to be able, at tops speed, to run a course between buoys. Flats boats skid in turns and can not do that slalom when overpowered. It is a matter of safety.
I ran Cigarette boats at more than 100 mph but I get scared in a flats boat going 50.

Posted: **Fri Sep 10, 2021 2:41 pm**

TomW1 wrote: ↑Fri Sep 10, 2021 1:58 pm ProfrsX Why do you keep insisting on a 250HP motor, are you build this for bass tournaments? Jacques just said he would give you the laminating schedule for a 125HP but not for a 250HP motor. Like I posted above a 250HP will give you speeds around 70mph, speeds that Jacques does not design his boats for as he does not want to take the liability for. If you want to add extra glass to the outer and inner hull and beef up the transom, that is your choice and your responsibility and your liability.

Did I miss a follow-up response with him stating this? As a matter of fact, he stated the complete opposite. To include two alternative lamination schedules that he claimed he would send. He only stated that it would not be possible to use divinycell foam core from the chines to the keel and that he would likely put in a disclaimer. No, I will not be fishing bass tournaments, I like to challenge myself lol. I will be fishing inshore tournaments and know what kind of performance I need out of a boat.

P

Posted: **Fri Sep 10, 2021 4:11 pm**

ProfrsX Why do you keep insisting on a 250HP motor, are you build this for bass tournaments? Jacques just said he would give you the laminating schedule for a 125HP but not for a 250HP motor. Like I posted above a 250HP will give you speeds around 70mph, speeds that Jacques does not design his boats for as he does not want to take the liability for. If you want to add extra glass to the outer and inner hull and beef up the transom, that is your choice and your responsibility and your liability.

Did I miss a follow-up response with him stating this? As a matter of fact, he stated the complete opposite. To include two alternative lamination schedules that he claimed he would send. He only stated that it would not be possible to use divinycell foam core from the chines to the keel and that he would likely put in a disclaimer. No, I will not be fishing bass tournaments, I like to challenge myself lol. I will be fishing inshore tournaments and know what kind of performance I need out of a boat.

Yes you messed up he is only giving you a 1. laminating schedule for the bottom and 2. the sides. That is all he said. As far as Divynicel it cannot be used for the speeds you want to reach as he points out in one of his posts. Please read his latest 2 posts above before responding. You are reading things into what we are saying that you want to hear that just are not true. You obviously did not read them.

If you want a boat that will handle a 250HP motor took at the Maangusta 20, Lee down in Australia modified it into one fine fishing machine. He stretched it 10% viewtopic.php?f=12&t=37727

Tom

Posted: **Fri Sep 10, 2021 4:51 pm**

TomW1 wrote: ↑Fri Sep 10, 2021 4:11 pm
ProfzrX wrote: ↑Fri Sep 10, 2021 2:41 pm
TomW1 wrote: ↑Fri Sep 10, 2021 1:58 pm ProfrsX Why do you keep insisting on a 250HP motor, are you build this for bass tournaments? Jacques just said he would give you the laminating schedule for a 125HP but not for a 250HP motor. Like I posted above a 250HP will give you speeds around 70mph, speeds that Jacques does not design his boats for as he does not want to take the liability for. If you want to add extra glass to the outer and inner hull and beef up the transom, that is your choice and your responsibility and your liability.

Did I miss a follow-up response with him stating this? As a matter of fact, he stated the complete opposite. To include two alternative lamination schedules that he claimed he would send. He only stated that it would not be possible to use divinycell foam core from the chines to the keel and that he would likely put in a disclaimer. No, I will not be fishing bass tournaments, I like to challenge myself lol. I will be fishing inshore tournaments and know what kind of performance I need out of a boat.

Yes you messed up he is only giving you a 1. laminating schedule for the bottom and 2. the sides. That is all he said. As far as Divynicel it cannot be used for the speeds you want to reach as he points out in one of his posts. Please read his latest posts before responding. You are reading things into what we are saying that you want to hear that just are not true.
If you want a boat that will handle a 250HP motor took at the Maangusta 20, Lee down in Australia modified it into one fine fishing machine. He stretched it 10% tp 22' viewtopic.php?f=12&t=37727

Tom

He gave two separate recommendations on how to achieve the HP I am wanting. One with a more durable foam core and the other "you will plank with a sheet of heavy glass laminate: just like you would do with a plywood bottom. You could even use vinylester". I am not "reading things the way I want to hear them" I'm actually quoting his words. If I wanted the manngusta 20 then I'd of purchaused those plans. Tom, you have ZERO knowledge of conversations that took place with BBC prior to my decision on building this boat. Unless you will be the one designing the changes needed for what I was told I could accomplish with this build with the materials that I wanted to use, then your opinion is not needed.

P

Posted: **Fri Sep 10, 2021 4:57 pm**

Well I am listening to what Jacques is saying and what he and I have talked about before. He and I have the same amount of courses at the Westlawn School of Yacht Design and can relate to each other though he has the practical experience of designing at Pursuit and Cigarette and here. He told you he will give you the laminations for a 125HP motor and NOT for a 250HP motor. Why can't you get that through your thick head and stop asking him to? People have put a 150HP motor on the PH22 with no problems. Do not over power Jacques boats, they are designed to do what they are designed to do. They are lighter and require less HP for the speeds they attain. Look Jacques philosophy is basically to design boats for home builders that are safe and easily built and long lasting, not high speed specialty boats. He wants to sell plans that will sell.to those most likely to buy them. As I told you before if you want to put a 250HP on the PH22 it is on you, determine what foam you need and what the fiberglass layups you need. I would start with what Jacques gives you and go from there, check with BBC for a better bottom foam, and see if Reid can give you any indication on layup.

Tom

Posted: **Sat Sep 11, 2021 9:38 am**

TomW1 wrote: ↑Fri Sep 10, 2021 4:57 pm Well I am listening to what Jacques is saying and what he and I have talked about before. He and I have the same amount of courses at the Westlawn School of Yacht Design and can relate to each other though he has the practical experience of designing at Pursuit and Cigarette and here.
…
Why can't you get that through your thick head and stop asking him to?

Tom

This shit just needs to stop. Nobody gives a crap what correspondence courses you’ve taken.

Nobody appointed you deputy here, and Jacques certainly doesn’t need your help.

Your pompous attitude doesn’t fit in with the ethic of this community.

Posted: **Sat Sep 11, 2021 10:31 am**

I think this conversation needs to be a phone call to solve what can and won’t be provided. this is basically a custom job, and a couple comments aren’t going to get a safe boat built.

Objectively, i read that he would provide an alternate keel method that would support a 250hp and then later that he wouldn’t just one for up to 150 hp.

Either way, clearly not going to be resolved here.

Also, it is confusing sometimes when people jump in for Jacques the conversation gets muddled as far as what Jacques is actually recommending or agreeing with. I get it he is busy, and I get that Jacques wants some of these questions answered here, so the private emails are managable. but when it is a clear design question that leads to a deliverable, best to keep the personal opinions out so the best answer can be provided.

Posted: **Sat Sep 11, 2021 10:23 pm**

An interesting thread, that took a sudden nose dive - perhaps not unlike a PH22 doing 70 mph!

I have mates who drive boats that they claim will do 100 mph. Interesting when they fish in a area with a 50 mph speed limit - and a healthy crocodile population. They do look cool throwing a big rooster tail - but obviously have bigger 'coconuts' than I do!

I see I get a mention above!

If you want a boat that will handle a 250HP motor took at the Mangusta 20, Lee down in Australia modified it into one fine fishing machine. He stretched it 10% viewtopic.php?f=12&t=37727

Yes, I have a Yammie 250 vmax SHO on my Mangusta hull stretched to 22' - and I have run it at 60 mph on smooth water, although its set up for power rather than speed. It will do that quite comfortably but I rarely run it above 35 mph - OK, maybe an occasional 50 mph if someone who thinks they have a faster fishing boat tries to pass me!

After lots of experience with my boat I would be quite happy to put 300 hp on it, but I would have to put it through the test that Jacques refers to, in order for it to be legal!

Posted: **Sat Sep 11, 2021 11:07 pm**

Hi Steve. Stuart from NZ. I posted in here before.

In my experience Jacques is conservative with his designs. Like all good engineers he factors in a margin of safety. For home built boats this tends to be especially wide as there is large variance of quality from builder to builder and boat to boat. Keep in mind that he is semi retired, and often details get lost in translation.

Frankly I think that it's nuts putting a 250hp on a PH22, but that's your lookout not mine. I really look forward to seeing the results so hope that you continue to post here. It might help if you give the designer an indication of the speeds you were hoping to reach, and the conditions in which you are taking it. Are we talking full speed in flat water only, or will there be waves? Will you slow down in them?

If this were my boat I'd take the advice to build the bottom single skin seriously. You would still need the foam to make the shape, so it's not a total loss. Better to find out now than after you've got it in the water.

I also think that a phone call would help.

Don't take my nuts comment too personally, nothing would ever get done without the crazy people pushing the envelope.

Edit: Of course I'm a kiwi, we only went to outboards after we ran out of sheep.

Posted: **Sun Sep 12, 2021 12:36 am**

Hi Steve Tomw here hope there are no hard feelings. Though some think I made a comment I should not have, if so I am sorry. If you want to put a 250HP on the PH22 lets point you in the right direction. 1. When you add power and speed the forces on the bottom go up by an exponential factor. By the time you get to 70 the forces on the hull are about 4x the amount they are at 45mph. 2. What does that mean? We need to double the amount of frames to support the bottom and we need to strengthen the bottom. This will be in two steps, first using 3/8" plywood and they 17oz biax fiberglass, outside and inside. If you use Okume this will probably add only 150lbs to the weight of the boat. 2. Now I can't tell you how many layers of 17oz to lay that is not my expertise. Or how to lay them. But the rest is solid design information to strengthen your boat for your 250HP.

I really don't want you to put that 250HP on the PH22 as currently designed and have it come apart at the first big wave you hit.

That is what I have been trying to say all along it is not just a simple step of adding glass but of adding structure and reinforcing the bottom and adding glass.

I had time today to think about it more and this is what I came up with.

Well good luck and fast boats.

Tom

Posted: **Sun Sep 12, 2021 2:24 pm**

All, this thread has taken a negative tone and I just want all to know that Steve is working directly with Jacques regarding the lamination schedule(s) in attempt to meet Steve’s requirements. Your continued comments are welcome as long as they are positive and don’t take further aggressive tone. Our forum is here to support all but when a question is asked of Jacques, please give home time to respond back with a thorough answer. Steve is now in direct coordination with Jacques and I am comfortable they will reach a good conclusion!!! Thank you, Jeff

Posted: **Sun Sep 12, 2021 2:26 pm**

I am interested in this build. I want the boat to do 30mph top speed with 800# pax. Any idea what power it'd need?

Gonna go read the thread more.

Oh, I remember now, this is a foam build.

Does BBC offer cnc cutting of the divinycell? I am a few years away.

Posted: **Sun Sep 12, 2021 2:47 pm**

Yes, we can CNC foam for you as long as it is the standard Jacques plans!!! Or if you have your own DXF Files we can cut for you!!! Jeff

Posted: **Sun Sep 12, 2021 3:01 pm**

So, it this hull built on male stations or on it's final bulkheads and some sacrificial jigs?

How does it not lose shape when flipped?

Posted: **Sun Sep 12, 2021 3:10 pm**

Question for Jacques FallGuy!!!! Sorry, Jeff

Posted: **Sun Sep 12, 2021 3:20 pm**

Jeff wrote: ↑Sun Sep 12, 2021 3:10 pm Question for Jacques FallGuy!!!! Sorry, Jeff

Jacques, if you could reply, I'd appreciate it. I am trying to wrap my head around the how and would be happy to help Steve. Sorry to mess around on the thread. I actually have a ton of questions for Steve as well. Like is this going to be hand laid glass?

Posted: **Sun Sep 12, 2021 7:02 pm**

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Jeff wrote: ↑Sun Sep 12, 2021 2:24 pm All, this thread has taken a negative tone and I just want all to know that Steve is working directly with Jacques regarding the lamination schedule(s) in attempt to meet Steve’s requirements. Your continued comments are welcome as long as they are positive and don’t take further aggressive tone. Our forum is here to support all but when a question is asked of Jacques, please give home time to respond back with a thorough answer. Steve is now in direct coordination with Jacques and I am comfortable they will reach a good conclusion!!! Thank you, Jeff

Thank you, Jeff, I concur.

Tom, none was taken if I came across as abrasive I also apologize, I didn't want what I needed from Jac to be lost in conversations or others just throwing out what they thought was best. LOL. I hope it didn't come across as I was devaluing or discrediting your knowledge, that was not my intention. The reason I am here is to be able to get advice from knowledgeable builders like yourself. I was never under the impression that I would be able to accomplish what I want to do without some modifications. As I stated earlier I have had extensive conversations with Jeff, Reid, and also Jac (pre-retirement) prior to even buying the plans on how to build this hull (wood free) and safely accomplish this with the HP I am wanting. Honestly, this has been about 2-3 years in the making for me LOL.

If I may explain a little further in detail here about what I want from this build. My career is in pre-hospital critical care flight medicine so I apologize if I don't elaborate as well as others lol. I've been programmed to obtain or deliver as much information as possible with as few words as possible and unfortunately, this also carries over into my personal interaction. Anyhoo, Just because I have a 250hp doesn't mean I'll be using its full potential in every condition, Hell if I could put a yamy 450Hp on it I probably would. I'm a, rather have it and not need it over need it and not have it kind of guy. I have designed the layout of this boat for the main purpose of fishing. But it will also be used for other water sports such as wakeboarding, tubing, kneeboarding, scalloping, diving ect. On the same token, I plan on getting back into inshore fishing tournaments, which means if I'm even 2mph faster than the next guy I'm getting to the honey hole first. Anyone who fishes shotgun tournaments knows this could mean 10K in prize $ or $0. I fish the big bend area in the GOM, a good day is glass and an average day is 1-2' chop depending on winds and tides. I don't believe I'll get 70mph out of this hull. I have added up the total weight with what I'll be equipping this boat with and it's right in line with my buddy's gulfshore 22' (what I'll be mirroring this hull and layout from. I'll attach a pic also) he sees mid 50's with tournament weight.

*Fallguy, my original plan was to use sacrificial jigs, laid out per plans secured to a level 4'x21' frame with vertical posts and horizontal braces from bulkhead to bulkhead. then recess out each bulkhead with a router every 4-6" so that I could run 1"x4" SYP or PVC board flush with bulkhead frame for the foam to lay on. Then build out a horizontal platform to give me 6-8" past the edge of the gunwale. I was going to use this "lip" as a way to build a mold for my rub rail to attach to glass. I also had planned on using the vacuum bag method so it would also give me a sealing point for the tape or just hand lay glass. I will say I really like the idea of using cheap foam and making a glass skin then building it up. Depending on what that lamination schedule will consist of I may even..............Brace yourself, build a female mole using the same methods as mentioned above only in reverse then using something like formica board for the glass to lay on as that already has somewhat of a wax finish to it, I'm sure Ill need to add a little more though. How about that for a curveball LOL.

Holy Essay LOL. As always I appreciate any feedback. Thanks. This is the finish look I'll be going for.

Posted: **Sun Sep 12, 2021 8:48 pm**

Great looking boat - but I can't imagine sitting up there doing 70 mph!

PS: Interesting looking power-poles!

Posted: **Sun Sep 12, 2021 10:25 pm**

Well, for sure, there needs to be some clarity about how to keep the hull true.

I apologize, I don't follow the plan for sacrificials. Doing the boat as a female is nice, but requires either prelaminating everything or flipping multiple times.

I'll keep watching. Offer what help I can..

Posted: **Mon Sep 13, 2021 12:10 am**

Steve this is TomW sounds like you have Jacques working on this off Forum so I have more to give you at this point. I am not an expert in foam and the laminations required so will leave you Jacques capable hands. However as you get the boat close to completion, give me a ring and I will help get the best prop for your motor and boat. Have been doing it for nearly 15 years for the guys on here and usually can hit it on the first calculation or be off by one pitch. Since you are going to be running at high speed and fishing shallow water, I will recommend a 4 blade prop. They do a couple of things, they help maintain straight line steering, in shallow water you can raise them an 1" or two to allow you to get a little skinnier, if you have a jack plate.

Well I will keep watching and once you start if I have any suggestions I will make them.

Until then regards, and red seas at night.

Tom

Posted: **Mon Sep 13, 2021 1:30 am**

Did you buy the core?

The core might need to be made from thicker materials for 250hp. For all that speed, you need a stiffer bottom and foam core and others use the cube rule. So, for any bottom, core A versus core B works as follows.

Thickness of Core A stiffness is X

Core B is raised to 3rd power to get stiffness

So, for example.

A 1" core is stiffness X.
A 2" core is 8 times stiffer.

Or for a 1/2" core, a 3/4" core is 1.5^3 or 3.375 times stiffer.

Yes, it can be done with fiberglass, but epoxy, glass, weight, money are the cost..

Now, I saw what happened here on the thread with all the other business, so I won't say more, but the foam thickness needs some discussion and I offer this as a friendly conversation starter with the designer; nothing more.

Posted: **Mon Sep 13, 2021 7:22 am**

Stiffness of a single skin scales as the cube, sandwich panels scale as the square of the core or separation between skins. If you recall Calculus this should make sense as the Integral of the square is a cube. The cores integral stiffness scales as a cube, which matters for ply, but since nearly all the strength is in the skins, that scales as a square.

There's a discussion on this on page 6 of the Diab handbook. I'd never build from foam core when ply is cheaper, but I'm one of those that enjoys reading formulae.
http://www.stmboats.com/articles/sandwich_hb.pdf

Steve your comments on HP and the speed you want out of your boat make sense. I'm happy at a much lower speed; that style of tourney fishing is not a NZ thing.

Posted: **Mon Sep 13, 2021 8:35 am**

OneWayTraffic wrote: ↑Mon Sep 13, 2021 7:22 am Stiffness of a single skin scales as the cube, sandwich panels scale as the square of the core or separation between skins. If you recall Calculus this should make sense as the Integral of the square is a cube. The cores integral stiffness scales as a cube, which matters for ply, but since nearly all the strength is in the skins, that scales as a square.

There's a discussion on this on page 6 of the Diab handbook. I'd never build from foam core when ply is cheaper, but I'm one of those that enjoys reading formulae.
http://www.stmboats.com/articles/sandwich_hb.pdf

Steve your comments on HP and the speed you want out of your boat make sense. I'm happy at a much lower speed; that style of tourney fishing is not a NZ thing.

So, how does that work in my example for Steve?

Separation of 1/2" core versus 3/4" core is 1.5^2 or 2.25 times only versus my citation of 3.375? (For same skins)

Meaning a 1" core is 4 times stiffer than 1/2" core?

Building this speed demon from foam might require thicker foam and more bulkheads and even more long tees then.

I gotta read that Diab text because this is new to me. And I'm even more curious about the foam plan/layup.

Steve---how you build a foam bottom is really critical because if you have even small air pockets on the bottom; those pressures are rather significant at 70mph and the laminate can erode quickly. You can't allow them; fyi. Any air pocket must be ground or injected fully and then the injection site faired. I am not trying to beat any dead horses here. Just inform. I don't care how fast you want to go. I would even be looking at the shear ratings of various cores. You want something very high as a skin failure is certain in any lower shear foams. The shear rating of corecell M60 is about 100psi and the shear rating of M200 is over 400psi. I know from my reading that the shear must be addressed in go fast changes. (The water pounding forces are very high; no joke). What would happen if you build a beautiful hull with a low shear rating is it would delam from either a small impact or jist wav pressure and that delam would grow under hydraulics. Another reason to probably bag the job... The designer must do calculations of the shear demands and specify a core capable...I don't know those calcs, btw, jist that they are required.

Another thing to be very mindful of in designing a go faster boat is the engine weight/moment for the bigger engine. 100 pounds? added stern weight must be addressed. If the designer knows the center of mass, the moment of the additional weights are known and you MUST create offsetting moments or the boat will squat. That moment in a ph22 is probably ?900ft#s. Moving a 40# battery forward 2 feet is only going to give you an 80 ft# offset, for example. Moving weights forward can create a bending stress on the hull, but this may be addressed in a core thickness change or adding another stringer. Ultimately, the boat will need more weight moved forward.

Kindest regards. It is easy to sound like I am against the plan, but I am actually looking out for some true pitfalls for you.

Posted: **Mon Sep 13, 2021 11:07 am**

Wow, what a debate.

I was working on the "high" speed lamination schedule this week-end and did not visit the forum.

Let's clarify where we stand:
- I will give a lamination schedule for the PH22 with the specified max. HP in the study plans
- I state very clearly that 250 HP on a PH22 will be excessive and dangerous, this can be confirmed by the USCG rules.
- if a builder absolutely wants to build a foam cored PH22 for 250 HP, I will give optional "experimental" specifications, no guarantees.
- the building of such a boat will be much more complicated than a standard PH22 in foam. Many details will be different like centerline keel lamination, stringers on pads, chine and deck to sides seam etc. etc. It will require a different type of foam, different layup, different tabbing and I must create drawings for that. I am tempted to scan pictures of my text books and design manuals to save a couple of days of work. Because of copyrights, I will not post those scans but will email them to the builder.

It is my intention to redesign some of my boats for foam sandwich but I did not plan to design a foam cored PH22 for 250 HP.
For most boats, my current specs for foam sandwich are simple, the boats are easy to build. This one will be complicated and costly.
I will help the builder to end up with the best possible boat but I can not guarantee the result.

Posted: **Mon Sep 13, 2021 1:17 pm**

Sounds like OP wants to build the PH22 like the Morejohn microskiffs. Lots of cool builds going on over there, but the weight and speed are in a different category.

And the 250hp desire is understandable, as so many production 22' bay boats can be powered that way. Frankly if I were going that path, I'd probably draw up (or commission) the design from scratch since you won't be limited by the plywood bend constraints.

Can't comment on the lamination, but I have rebuilt (re-cored) two speed boats, one for +/-80mph and one for 100+. I replaced the existing rotten butcher-block balsa core on the running surfaces with 5/8" Corecell A500. For two reasons - it is much tougher than the PVC foams, and the perforation is set up to vacuum bag it in place for good resin dispersion. I did use Divinycell H80 for bulkheads, stringers, seats - where they don't see the slamming and cyclic loads of the bottom, and are primarily a form for the glass skins. Hopefully you can find a use for the foam you have bought already.

Posted: **Mon Sep 13, 2021 3:57 pm**

Matt Gent wrote: ↑Mon Sep 13, 2021 1:17 pm Sounds like OP wants to build the PH22 like the Morejohn microskiffs. Lots of cool builds going on over there, but the weight and speed are in a different category.

And the 250hp desire is understandable, as so many production 22' bay boats can be powered that way. Frankly if I were going that path, I'd probably draw up (or commission) the design from scratch since you won't be limited by the plywood bend constraints.

Can't comment on the lamination, but I have rebuilt (re-cored) two speed boats, one for +/-80mph and one for 100+. I replaced the existing rotten butcher-block balsa core on the running surfaces with 5/8" Corecell A500. For two reasons - it is much tougher than the PVC foams, and the perforation is set up to vacuum bag it in place for good resin dispersion. I did use Divinycell H80 for bulkheads, stringers, seats - where they don't see the slamming and cyclic loads of the bottom, and are primarily a form for the glass skins. Hopefully you can find a use for the foam you have bought already.

I'll try to avoid extended debate and this is not a critique of your work Matt, but the problem with the a500 core is the interface between the bottom or top deck and the sides. JM will show the OP what to do, but what happens with an a500 core at the hulls edge is massive compression loading. Just think about it like this...instead of the a500 foam, put a neoprene sponge in place of the a500...it does fine until the sides of the boat press down on it. At that point, it is subject to massive crushing loads. So that interface requires special attention. So does the hull to deck interface for same reasons. The deck, in light(er) foam comes crashing down onto the hull sides which do not move and you can actually crush the foams. There are books written on these interfaces. The Skoota does not really need to consider these forces much because the boat is a wave cutter and not really supposed to jump waves, but go fast boats are subject to tremendous loads.

But an a500 bottom to hullside interface may not be sufficient. Again, only for the OP. Generally, a high(er) density core or a no core lamination occurs..but it gets far more complicated to build to avoid busting the boat at high speeds.

Posted: **Mon Sep 13, 2021 8:34 pm**

I found some old timer marine surveyer’s website talk about this exact problem and his observations that is why so many of these balsa or otherwise cored boats had hull failures, was in the early days people didn’t know to consider these things small failures led to water intrusion then core failure completely as the absorbed water basically crushed the core every time the boat hit a wave. His observations where everything from sailboats to fast fishing boats. I’ll try and find the website.

edit: website is here https://www.yachtsurvey.com/core_materials.htm

Now what I didn’t appreciate was his attitude was basically because someone had bad design in the past means no one can do it in the future successfully. which is BS.

why I think this is relevant is knowing how people have failed brings relevance to how the construction details in the plans are important.

fallguy1000 wrote: ↑Mon Sep 13, 2021 3:57 pm
Matt Gent wrote: ↑Mon Sep 13, 2021 1:17 pm Sounds like OP wants to build the PH22 like the Morejohn microskiffs. Lots of cool builds going on over there, but the weight and speed are in a different category.

And the 250hp desire is understandable, as so many production 22' bay boats can be powered that way. Frankly if I were going that path, I'd probably draw up (or commission) the design from scratch since you won't be limited by the plywood bend constraints.

Can't comment on the lamination, but I have rebuilt (re-cored) two speed boats, one for +/-80mph and one for 100+. I replaced the existing rotten butcher-block balsa core on the running surfaces with 5/8" Corecell A500. For two reasons - it is much tougher than the PVC foams, and the perforation is set up to vacuum bag it in place for good resin dispersion. I did use Divinycell H80 for bulkheads, stringers, seats - where they don't see the slamming and cyclic loads of the bottom, and are primarily a form for the glass skins. Hopefully you can find a use for the foam you have bought already.
I'll try to avoid extended debate and this is not a critique of your work Matt, but the problem with the a500 core is the interface between the bottom or top deck and the sides. JM will show the OP what to do, but what happens with an a500 core at the hulls edge is massive compression loading. Just think about it like this...instead of the a500 foam, put a neoprene sponge in place of the a500...it does fine until the sides of the boat press down on it. At that point, it is subject to massive crushing loads. So that interface requires special attention. So does the hull to deck interface for same reasons. The deck, in light(er) foam comes crashing down onto the hull sides which do not move and you can actually crush the foams. There are books written on these interfaces. The Skoota does not really need to consider these forces much because the boat is a wave cutter and not really supposed to jump waves, but go fast boats are subject to tremendous loads.

But an a500 bottom to hullside interface may not be sufficient. Again, only for the OP. Generally, a high(er) density core or a no core lamination occurs..but it gets far more complicated to build to avoid busting the boat at high speeds.

Posted: **Mon Sep 13, 2021 8:48 pm**

Oh, boy. All we needed was some Pascoe core hate.

...disregard; mostly

Posted: **Mon Sep 13, 2021 9:39 pm**

Everyone has an angle or a bias, as a surveyor (I think he's passed on now) I can understand his. If you are paid to survey a boat, and liable for getting it wrong, cores (especially below the waterline) are a problem. How can you tell whether the workmen paid attention when bonding the core to the outer skin? Did they get it right? Are you willing to risk $$$ on making the wrong call?

As home builders we can work at our own pace, use whatever methods and materials we please, and do our own QA. Different than trying to judge somebody else's work based on non invasive methods.

Posted: **Mon Sep 13, 2021 10:47 pm**

fallguy1000 wrote: ↑Mon Sep 13, 2021 8:35 am
So, how does that work in my example for Steve?

Separation of 1/2" core versus 3/4" core is 1.5^2 or 2.25 times only versus my citation of 3.375? (For same skins)

Meaning a 1" core is 4 times stiffer than 1/2" core?

Building this speed demon from foam might require thicker foam and more bulkheads and even more long tees then.

I gotta read that Diab text because this is new to me. And I'm even more curious about the foam plan/layup.

As I understand it yes.

I think the real issue is less the thickness of the core, and more the skin/core interface. At those speeds I'd expect some pretty hefty skins to be specified, which is why part of me wants Steve to build as per standard, and part of me wants to see an extreme build. Either way I will be following this thread.

If there was a pool for guessing the final layup I'd be putting my money on a 3/4" core (at least 100kg/m density) and about 4/3mm of directional glass on the outer skin and inside respectively. I could be way off obviously.

Posted: **Mon Sep 13, 2021 11:08 pm**

fallguy1000 wrote: ↑Mon Sep 13, 2021 3:57 pm
I'll try to avoid extended debate and this is not a critique of your work Matt, but the problem with the a500 core is the interface between the bottom or top deck and the sides.

Yeah I wasn't getting into design/fab details at all. My applications (forgot about the 3rd one under way, will make a quick thread on that) for a500 were all on running surfaces in molded production boats. The core is laminated onto the outer skin to stiffen the large panels. It is not in position to take compressive loads, which are borne by the hull shape (keel pad, or strakes, or tunnel edges) or stringers in all glass areas. Edges of the foam were tapered down or butted against stiff vertical members with glass fillets.

My point was simply that the expensive stack of H80 already purchased is not optimum and maybe not sufficient for the hull surfaces.

Posted: **Wed Sep 15, 2021 5:25 pm**

You are for sure a class act Matt. Needed no reply.

Here are a few pics for the OP of honeycomb work. He asked privately about raw edge management is all. I like he is thinkin ahead. I used scraps for this edgefill, so the abc is so I remember when the glue is ready! Look close and you can see it is lightly clamped. I did add weight on panel corners to keep vertical alignment, but it is never perfect and requires some sanding or filling later.

The aluminum post holes were after the fact. Drilled to 3/4" and refilled for 1/4" bolts. Don't be fooled by those nuts; there is a carbon backer going there; just needs paint first!

Posted: **Wed Sep 15, 2021 5:41 pm**

My inserts were almost too narrow at 1.25", too. Try to avoid skimping.

Some people purposely leave inserts high or low to find them later. I am on the hardtop.

Order enough coosa for the transom and for cleats and i nserts. Benchtops in 1/2-3/4" coosa are wise as is the entire gunwhale.

Used 3/4" marine ply in a benchtop that filled with water here in the yrd and it broke my laminate and messed up my paintjob

Freight is so costly, make sure to get plenty of hd core for inserts, transom, gutters even. I made gutters from aquaplas. There are different weights of hd core. 26# for transom, 20# for benchtops and screwholds, 12# for in hull load inserts or as spec'd by JM.

I had to buy more core along the way fir this build...freight is a bugger. I expect you'll experience some of same. Make sure to use a 25% waste factor. Yes you can buuld up core and use small pueces like I showed, but damnit if a guy misses stuff..

Posted: **Wed Sep 15, 2021 5:48 pm**

In a foam boat, you don't really put many screws into the hull.

For one; they hold poorly in 4-5# density. For another why risk it? So, you use standoffs ir cleats. Yeah, frim scrap, but only if you have some.

These are 1.5" cleats and a 1/2" aquaplas standoff.

Posted: **Wed Sep 15, 2021 6:47 pm**

I'm not sure I understand what you mean by standoffs on cleats. Is it that instead of say screwing a wiring board or transducer into the hull, you screw it into a foam/glass or ply pad that is glued to the hull?

Posted: **Wed Sep 15, 2021 7:01 pm**

Its interesting to read a thread .................. and have absolutely no idea what anyone is talking about !

Posted: **Wed Sep 15, 2021 7:20 pm**

OneWayTraffic wrote: ↑Wed Sep 15, 2021 6:47 pm I'm not sure I understand what you mean by standoffs on cleats. Is it that instead of say screwing a wiring board or transducer into the hull, you screw it into a foam/glass or ply pad that is glued to the hull?

Yes. I use weldmount adhesive. It is spendy, but about 30 minutes after gluing you can start mounting to the standoffs

Cleats are just a place to screw to that is not the honeycomb. For example, a center console could be attached with screws or bolts. This would make it easier to work on inside the garage in summer or removable, in my case.

Steve asked me about using honeycomb is all. So I wrote some stuff about how to use honeycomb.

Posted: **Wed Sep 15, 2021 7:28 pm**

This standoff is just a scrap piece of 1/2" aquaplas. It won't rot or suck water. It may mildew.

The hull thickness here is about 5/8", but a 1/2" screw is nervewracking, so the aquaplas makes it an inch thick hull and better screwholding in say a 20-26# density core than the 4# core..

4# hull core does not hold screws really...they can pull or lay over easily,,

Posted: **Wed Sep 15, 2021 9:49 pm**

BarraMan wrote: ↑Wed Sep 15, 2021 7:01 pm Its interesting to read a thread .................. and have absolutely no idea what anyone is talking about !

there are like 7 parallel conversations

also. I hope steve starts a new thread for his build. I hope he still documents it here. I’m in with the

Posted: **Wed Sep 15, 2021 10:03 pm**

If Steve follows the specs; it'll be THE coolest build ever.

Posted: **Thu Sep 16, 2021 3:59 pm**

fallguy1000 wrote: ↑Wed Sep 15, 2021 5:41 pm My inserts were almost too narrow at 1.25", too. Try to avoid skimping.

Some people purposely leave inserts high or low to find them later. I am on the hardtop.

Order enough coosa for the transom and for cleats and i nserts. Benchtops in 1/2-3/4" coosa are wise as is the entire gunwhale.

Used 3/4" marine ply in a benchtop that filled with water here in the yrd and it broke my laminate and messed up my paintjob

Freight is so costly, make sure to get plenty of hd core for inserts, transom, gutters even. I made gutters from aquaplas. There are different weights of hd core. 26# for transom, 20# for benchtops and screwholds, 12# for in hull load inserts or as spec'd by JM.

I had to buy more core along the way fir this build...freight is a bugger. I expect you'll experience some of same. Make sure to use a 25% waste factor. Yes you can buuld up core and use small pueces like I showed, but damnit if a guy misses stuff..

Thank you for the information. Have you used the aquaplas on any other builds? My concern would be screws backing out on places where I cannot use a thru bolt with backer nut. What I like about the pultruded fiberglass is you can tap and die it to hold screws. Ive also been told and have read on other forums that Coosa will not hold screws. I guess the bluewater 26 is said to be able to by the manufacture but some have done tests showing they typically fail.

Posted: **Thu Sep 16, 2021 6:13 pm**

ProfzrX wrote: ↑Thu Sep 16, 2021 3:59 pm
fallguy1000 wrote: ↑Wed Sep 15, 2021 5:41 pm My inserts were almost too narrow at 1.25", too. Try to avoid skimping.

Some people purposely leave inserts high or low to find them later. I am on the hardtop.

Order enough coosa for the transom and for cleats and i nserts. Benchtops in 1/2-3/4" coosa are wise as is the entire gunwhale.

Used 3/4" marine ply in a benchtop that filled with water here in the yrd and it broke my laminate and messed up my paintjob

Freight is so costly, make sure to get plenty of hd core for inserts, transom, gutters even. I made gutters from aquaplas. There are different weights of hd core. 26# for transom, 20# for benchtops and screwholds, 12# for in hull load inserts or as spec'd by JM.

I had to buy more core along the way fir this build...freight is a bugger. I expect you'll experience some of same. Make sure to use a 25% waste factor. Yes you can buuld up core and use small pueces like I showed, but damnit if a guy misses stuff..

Thank you for the information. Have you used the aquaplas on any other builds? My concern would be screws backing out on places where I cannot use a thru bolt with backer nut. What I like about the pultruded fiberglass is you can tap and die it to hold screws. Ive also been told and have read on other forums that Coosa will not hold screws. I guess the bluewater 26 is said to be able to by the manufacture but some have done tests showing they typically fail.
What screws is the question..

A screw holding a bus bar isn't going to fail in aquaplas as fast as it will in an M80 or M100 corecell core.

But you won't mount the console with screws; you'd use glass on the inside of the cleat and the console face and you'd bolt with 1/4" and finish washers.

I don't have anything screwed that matters; save for maybe the gas tank fills, but they are also bedded in butyl, so fat chance they ever come out.

I have some bolts planned for yellow loctite as well and green for the helm bolts.

What you need for bolt holding is crush resistance. 3 ways to get it.

1. Hd foam inserts
2. Overbore 2-3x and fill and redrill (all plywood gets overbored to prevent rot)
3. Metal bushing to precisely the thickness/depth of the hole.

Posted: **Thu Sep 16, 2021 6:15 pm**

Further, if the aquaplas allows a screw to turn out (can't see it), I can always glue the bus bar down on four corners.

You have a different game going with a go fast wave jumper, but I'd trust the aquaplas higher or coosa bw to hold a busbar.

Posted: **Fri Sep 17, 2021 11:46 am**

fallguy1000 wrote: ↑Mon Sep 13, 2021 3:57 pm . . . but the problem with the a500 core is the interface between the bottom or top deck and the sides. JM will show the OP what to do, but what happens with an a500 core at the hulls edge is massive compression loading.

I'm back. The remark above is correct and very important. A few days ago, I did email Matt a few drawings explaining how to handle those corners (I call them hinges). The solution is a transition to single skin. I don't want to post the drawings here, I am afraid that they my be copyrighted. I may redraw them my way.

More further down.

Posted: **Fri Sep 17, 2021 11:51 am**

OneWayTraffic wrote: ↑Mon Sep 13, 2021 10:47 pm

As I understand it yes.

I think the real issue is less the thickness of the core, and more the skin/core interface. At those speeds I'd expect some pretty hefty skins to be specified, which is why part of me wants Steve to build as per standard, and part of me wants to see an extreme build. Either way I will be following this thread.

If there was a pool for guessing the final layup I'd be putting my money on a 3/4" core (at least 100kg/m density) and about 4/3mm of directional glass on the outer skin and inside respectively. I could be way off obviously.

Correct, it is shear failure that worries me. Either in the foam or at the interface. That is why I must specify Corecell 500 for high speed.

Posted: **Fri Sep 17, 2021 12:08 pm**

I was busy on some other projects, some personal but worked on the lamination schedule.
It took me a while to realize that Matt was the DE23 Matt. I would have worked faster.
Anyway, the lamination schedule in the very first post was not far off considering that it was for polyester.
I use less glass but still, the bottom is thicker than some 25' moderate vee boats.

This week-end, I will send Matt my specs for different versions.
I used different types of calculations and for 250 HP (I did set it at 40 knots and 3,500 lbs), I always get a quite thick bottom.
It is mostly because of the deadrise. In his formulas, Dave Gerr does not introduce deadrise as a variable but all others do.
That boat is not going to be lighter than a plywood cored one.
Even with Corecell and careful building, I am still worried about shear failure with 250 HP.

For the Divynicell that Matt bought, let's use it for the stringers, frames, soles and deck. It will not be wasted. The stringers are 2.5" wide now!

Posted: **Fri Sep 17, 2021 2:07 pm**

jacquesmm wrote: ↑Fri Sep 17, 2021 12:08 pm I was busy on some other projects, some personal but worked on the lamination schedule.
It took me a while to realize that Matt was the DE23 Matt. I would have worked faster.
Anyway, the lamination schedule in the very first post was not far off considering that it was for polyester.
I use less glass but still, the bottom is thicker than some 25' moderate vee boats.

This week-end, I will send Matt my specs for different versions.
I used different types of calculations and for 250 HP (I did set it at 40 knots and 3,500 lbs), I always get a quite thick bottom.
It is mostly because of the deadrise. In his formulas, Dave Gerr does not introduce deadrise as a variable but all others do.
That boat is not going to be lighter than a plywood cored one.
Even with Corecell and careful building, I am still worried about shear failure with 250 HP.

For the Divynicell that Matt bought, let's use it for the stringers, frames, soles and deck. It will not be wasted. The stringers are 2.5" wide now!

Pretty sure Steve is the original poster. Matt just contributed to the discussion. Sorry to confuse, but we are all trying to help a bit.

If you are worried about shear failure, then why don't you use a higher shear core Jacques? How does one calculate minimum shear of the skin if I may inquire?

My primary concern, as a builder, is laminate quality.

Steve may end up with a resin rich layup that performs poorly. Or, if he has a void, that will result in delam after paint.

I might have a laminate on my boat that is so dry, a barnacle ends up pulling glass (gulp).

I think the weight may end up only a wee bit less than ply. I'd be concerned even internals and furniture needs to be taped with heavier tapes. Instead of say a 6 oz woven or a 12 oz biax, a 1208 tape or even two or a 1708 or two, for example.

If I have the name wrong, please tell me.

Posted: **Fri Sep 17, 2021 4:33 pm**

Would strip planking in core foam, using little I-beams of epoxy putty between the strips help shear failure at all? Strip planking in wood is a common method here down under. The idea is that the epoxy putty fills fairly generous gaps in between the strips and the wood core can be pretty much any low weight wood, as the epoxy is strong enough by itself.

Posted: **Fri Sep 17, 2021 5:02 pm**

Not my project! Way too big a scope for me.

I just come to offer my experience and pithy commentary.

Posted: **Fri Sep 17, 2021 9:11 pm**

OneWayTraffic wrote: ↑Fri Sep 17, 2021 4:33 pm Would strip planking in core foam, using little I-beams of epoxy putty between the strips help shear failure at all? Strip planking in wood is a common method here down under. The idea is that the epoxy putty fills fairly generous gaps in between the strips and the wood core can be pretty much any low weight wood, as the epoxy is strong enough by itself.

Well, the problem with the concept is it is done as a shear web to prevent mass failure (when) the core fails. However, a shear web assumes failure, so we don't see it applied as a convention.

Posted: **Sun Sep 19, 2021 9:36 am**

Matt Gent wrote: ↑Fri Sep 17, 2021 5:02 pm Not my project! Way too big a scope for me.

I just come to offer my experience and pithy commentary.

Sorry. I think his first name is also Matt.

Posted: **Sun Sep 19, 2021 9:51 am**

ProfzrX, please confirm that you received my email with the specs. I did send first to the wrong email.
We can discuss details here on the forum.

Please be patient: I am retired and will be travelling a lot in the coming weeks. I may not always have internet access.

Posted: **Sat Oct 02, 2021 3:07 pm**

Good afternoon all, After having further communication with Jacquesmm, Jeff and Ried, unfortunately, I have decided to not move forward with this build. Jacquesmm did provide me with the information needed to complete the hull but I have decided to have a bare hull built professionally. I don't know what the "rules" are for this forum but I would still be more than happy to document that build here if allowed. With that being said, Jeff gave me a full refund on all the divinycell I purchased but was unable to take back the Coosa board as it was CNC cut to a PH22 transom. I will be selling those boards if anyone is interested or knows anyone interested in them. It's a total of (4) 4'x8' 1/2" sheets. I have plans for the PH18 & 15 and it looks like with some modifications these precut boards will work with both of them. I don't get on here very often so I will leave my contact number. Feel free to call or text me if interested. 352-414-9145 Steve.

Posted: **Sat Oct 02, 2021 9:06 pm**

So, if you are eating the freight on the divinycel, and you have the coosa.

What would you need for the coosa if you sent it back to bateau and would they take it back f it was paid for? And can the transom be built with coosa and rest of boat ply?

I am pretty sure I am building a plywood ph22, but not for awhile...so the question is whether Jeff has a spot to hide it or not...and does it fit the ply plan or how was it cut different, etc.

Sorry, but I can't take the inventory now. Only I would be willing to hold the price of the inventory if Jeff can find a home for it...or you may be better off with your builder taking it.

Sorry if this is rambling, best I can do.

Posted: **Sun Oct 03, 2021 1:31 am**

ProfzrX wrote: ↑Sat Oct 02, 2021 3:07 pm Good afternoon all, After having further communication with Jacquesmm, Jeff and Ried, unfortunately, I have decided to not move forward with this build. Jacquesmm did provide me with the information needed to complete the hull but I have decided to have a bare hull built professionally. I don't know what the "rules" are for this forum but I would still be more than happy to document that build here if allowed. With that being said, Jeff gave me a full refund on all the divinycell I purchased but was unable to take back the Coosa board as it was CNC cut to a PH22 transom. I will be selling those boards if anyone is interested or knows anyone interested in them. It's a total of (4) 4'x8' 1/2" sheets. I have plans for the PH18 & 15 and it looks like with some modifications these precut boards will work with both of them. I don't get on here very often so I will leave my contact number. Feel free to call or text me if interested. 352-414-9145 Steve.

Steve is it still going to be a PH22 then post it here. If not follk's have posted in both Anything Else or Cracler Larry's Corner.

Tom

Posted: **Sun Oct 03, 2021 8:26 am**

fallguy1000 wrote: ↑Sat Oct 02, 2021 9:06 pm So, if you are eating the freight on the divinycel, and you have the coosa.

What would you need for the coosa if you sent it back to bateau and would they take it back f it was paid for? And can the transom be built with coosa and rest of boat ply?

I am pretty sure I am building a plywood ph22, but not for awhile...so the question is whether Jeff has a spot to hide it or not...and does it fit the ply plan or how was it cut different, etc.

Sorry, but I can't take the inventory now. Only I would be willing to hold the price of the inventory if Jeff can find a home for it...or you may be better off with your builder taking it.

Sorry if this is rambling, best I can do.

It was CNC cut by BBC so I’m assuming it was cut per plans. I live close enough to BBC that I can personally take it to them. Unfortunately it cannot be used with the new build I asked to try and save some $$ lol. I would take $250 per board. Jeff did tell me he’d package and ship it if it sold on here. I don’t know what the shipping cost would be or if he has any storage room.

Posted: **Mon Oct 04, 2021 10:11 am**

fallguy1000 wrote: ↑Sat Oct 02, 2021 9:06 pm So, if you are eating the freight on the divinycel, and you have the coosa.

What would you need for the coosa if you sent it back to bateau and would they take it back f it was paid for? And can the transom be built with coosa and rest of boat ply?

I am pretty sure I am building a plywood ph22, but not for awhile...so the question is whether Jeff has a spot to hide it or not...and does it fit the ply plan or how was it cut different, etc.

Sorry, but I can't take the inventory now. Only I would be willing to hold the price of the inventory if Jeff can find a home for it...or you may be better off with your builder taking it.

Sorry if this is rambling, best I can do.

Fallguy,

If you are interested in purchasing the Coosa from Steve we can store it for you at the shop. I can tell you that the transom is cut to match the plans, no modifications. There are 4 layers of 1/2" with the seams offset for lamination.

Let me know if you decide to go forward with this.
-Reid

Posted: **Mon Oct 04, 2021 12:50 pm**

Let me clear it with the admiral.

Posted: **Sat Dec 18, 2021 9:48 am**

Guys, whatever happened on this stuff? I am still interested..sorry, somehow got busy trying to beat the cold and it was warm here well into December.

Posted: **Mon Dec 20, 2021 8:11 am**

FallGuy, I have not heard from Steve lately!!! Jeff

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