Thinking about building a bay boat

[Browndog]

A 150HP would make a PH22 fly!!! Jeff

Yes sir Jeff just finished running the PH22 with Yamaha's 115 since they don't have a 125 and the 150 for the PH22 at 2200lbs which is a 1000lbs over Jacques hull weight a 115 will be around 45 and a 150 is around 52mph. Will let Browndog decide how fast he wants to go. I helped him prop his earlier boat, still have it in my files.

Tom

Tom,

Thanks for running your projections. I appreciate the help you gave me on the FS 19 project.

The Yamaha 200 HP in line 4 four stroke outboard and the 150 HP digital are built on the same 2.8 Liter engine block and weigh about the same. I’m considering that might be the motor I would put on the Phantom 22.

Been reviewing what info. there is from build threads of the PH 18 and how they’ve been powered and the one thread of the PH22.

I saw that a prospective builder wanting to build the PH 22 with a larger than specified motor decided not to proceed with the project. I understand he was contemplating building with a foam core which complicated his project.

I would intend to build the boat as designed for marine plywood, fiberglass and epoxy. As I did with the FS 19, every exposed surface of the boat will be covered in fiberglass. At a minimum 4 oz cloth on non structural exterior surfaces.. Understandably this will add some weight to the hull due to the increased cloth and resin.

Wondering what if any changes do you think would be necessary to the fiberglass layup schedule of the hull, frames and/or stringers to accommodate the increased power and speed.

Would anticipate adding perhaps an extra layer of glass on the bottom of the hull? On the inside of the hull? On the keel and chine seems?

Also I will definitely install spray rails and/or reverse chines to the hull as well. Possibly lifting strakes and a keel strip.

Not sure who to ask with Jacques gone now. Hopefully Jeff will chime in too.

[Reid]

Browndog,

Jeff and I took a look at your latest post. Unfortunately, we cannot give any advice on lamination schedules as it pertains to changes to accommodate HP increases. As I know you are already aware, there are several factors to consider when increasing HP for a specific hull design.
- Weight Distribution and balance
- Frame spacing to accommodate for the increased pressures on the hull panels.
- Increased overall weight from the increased lamination schedule. This will have an affect on performance and the ability to remain "self-bailing".

These were all factors that I hear Jacques talk about many times.

Just proceed with caution, as I know you will.

-Reid

[fallguy1000]

You have to determine the speed change.

Then you can use the Gerr Sn number and the percentage change on the hull skins. Given the schedule is already done; it will be easy to modify, but you need to determine the new vessel speed.

You would also need to provide the laminate schedule in a private message.

Also, you ought to consider adding a bulkhead. 200/150 is 33% more power. Gerrs formulas are not superb for this.

You also need to account for the weight change and note the expected effect or moment. For most planing hulls; using 2/3rd the way back is a good r.o.t.

If you wanted to go to 250hp; I'd not participate.

[Browndog]

Just ordered the digital download plans. I’ll look through them and figure a few things out.

[TomW1]

Unfortunatly since Jacques has left us I am probably the only one who has taken courses from Westlawn and had support from Jacques when I made a suggestion. I would not recommend going to a 200HP motor unless you add an extra layer of 12oz biax outside and inside the hull. You are also going to need to adjust weights forwards of the console as the Yamaha 115HP motor HP weighs 380lbs and the 150HP motor and 200HP motor weigh in excess of 525;bs. The 115HP motor will get you up to over 40mph. I consider anything over that dangerous. If you want me to calculate what a 200HP motor would give you I will. Let me know.

Tom

[TomW1]

Unfortunatly since Jacques has left us I am probably the only one who has taken courses from Westlawn and had support from Jacques when I made a suggestion. I would not recommend going to a 200HP motor unless you add an extra layer of 12oz biax outside and inside the hull. You are also going to need to adjust weights forwards of the console as the Yamaha 115HP motor HP weighs 380lbs and the 150HP motor and 200HP motor weigh in excess of 525;bs. The 115HP motor will get you up to over 40mph. I consider anything over that dangerous. If you want me to calculate what a 200HP motor would give you I will. Let me know. Browndog I calculated the 150 for you earlier and that would be fine without making any changes to the boat. It is just going to 200HP when you reach the point you need to start to need to make changes. Your speed goes up to the upper 50's putting an exponential amount of force on the bottom.

Tom

[mhd]

Unfortunatly since Jacques has left us I am probably the only one who has taken courses from Westlawn and had support from Jacques when I made a suggestion. I would not recommend going to a 200HP motor unless you add an extra layer of 12oz biax outside and inside the hull. You are also going to need to adjust weights forwards of the console as the Yamaha 115HP motor HP weighs 380lbs and the 150HP motor and 200HP motor weigh in excess of 525;bs. The 115HP motor will get you up to over 40mph. I consider anything over that dangerous. If you want me to calculate what a 200HP motor would give you I will. Let me know. Browndog I calculated the 150 for you earlier and that would be fine without making any changes to the boat. It is just going to 200HP when you reach the point you need to start to need to make changes. Your speed goes up to the upper 50's putting an exponential amount of force on the bottom.

Tom

Well, I'm just about finished with the first year/module of Westlawn also. I'm working on the lines drawings assignments currently. It is an investment in time and brain-power but I've certainly enjoyed it up to now and learned a lot although I've a long way still to go. My initial aim in taking the courses was to be able to calculate the righting moments and other stability parameters for any boat, given its lines, and I can do that now at least. I've not done it for the VG23 yet, but that will come once the hull is complete and I can reproduce the actual lines from the boat I'm building.

I'll certainly sign up for the second year/module of Westlawn and see how it goes after that. Not a qualified naval architect by a long chalk though - just enough to get myself into trouble currently.

Mick

[Browndog]

Reid and Tom,

Thank you both for your responses. I appreciate your knowledge, help, support and encouragement and that is why I directed my questions towards y’all.

This would be the 6th boat I’ve built and completed in the last 9 years, not all of which have been documented on this forum.

I feel that I’ve got some understanding of what might be involved.

The only reason I mentioned thinking about the 200 HP engine is because it is built on the same engine block and is roughly the same weight as the 150. My thoughts were along the line of, “If I’m already paying the weight penalty for the 150 why not have the extra power of the 200?”

Tom, your point about some Manufacturers like Yamaha not making a 125 HP motor is also very relevant.

There may be others that are thinking about building the Phantom 22 with similar questions especially since the study plans state kind of vaguely, “We specify 7 persons or 2,000 lbs persons and gear with max 125 HP but the legal USGA calculations allow much more.” It isn’t clear if that is referencing the boats carrying capacity or it’s ability to handle more horsepower or both.

I’m already going to be adding weight elsewhere because I would cover the sole, deck and all exposed parts of the interior with at least light fiberglass cloth and resin which is considered optional in the building notes. Would most likely raise the sole at least a couple of inches to allow for more space under the sole for a single fuel tank and to ensure that the scuppers would not allow water intrusion. The 20 inches of cockpit freeboard as designed is plenty generous so I’m not concerned about losing a little bit.

I put an extra layer of fiberglass cloth on the interior of the FS 19 hull under the fuel tank and would expect to do something similar with the PH 22 regardless of what motor I put on despite not seeing that recommendation in the building notes for the PH 22, so it isn’t a big deal to do more if need be to handle higher speeds.

If I put the motor on a jack plate that creates additional considerations regarding weight locations which I’ve had to deal with before. Even with a trolling motor and batteries in the bow I expect other things like the livewell and baitwell locations would probably need to be positioned more forward as when full they can add a lot of weight.

Taking my time to gather input and trying to better document the planning process for the forum. Wouldn’t start a project until at least the end of this year or beginning of next year so that I could avoid the challenge of building in the heat of Coastal Georgia.

Thanks again for all the support and help so far.

Hope people that are following along are learning a bit about the planning process and the trade offs involved in different decisions.

[TomW1]

Dang it Brongdog I just wrote a full post and hit Submit and it diapeared. Well here goes agoin. If you want to go with the 200HP motor yfour top speed will be in the upper 50's and the pressure on the bottom will require you to add extra fiberglass to the hull outside and inside. The 150HP motor would only reach the low 50's and you would not need to make any modifications. With both the 150HP motor and 200HP motors you will need to make adjustments to the LCG They weigh 140lbs more than the 115 so at 10/11 behind the LCG that is 1400lbs of moment. You can start by moving the console and the men behind it forward. Then the anchor and chain and rode and whatever you can put in the locker's forwards. Just measure weight x distance to get the amount of moment.

One last thing since the PH22 is fairly flat even with a keel board you will need to be careful in turns if you go with a 200HP motor.

My gut still says go with a 115HP motor low to mid 40's is plenty fast enough for me.

Take care and post pics as you build your boat.

Tom

[OneWayTraffic]

I'm not going to reply in detail, but Gerr recommends an extra 1% of glass thickness for each knot of speed over 10 knots. You can run the math on it, but for a boat like the PH22, or MG20 I'd probably try to step up the hull core, and/or put an extra layer of glass on it, if going faster than recommended or scaling it up. Especially if going up in core is doable when you plank it, I see no downside.

An alternative would be to look at the scantlings of a boat of similar size and speed, and extrapolate from that.