HC16 - Modified bow shape

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JohnFixes
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HC16 - Modified bow shape

Post by JohnFixes »

First time, long time (recently registered, but long time lurker). Plans for HC16 were purchased last week... Birthday present from me to me. I'm not a huge fan of the reverse curvature at the bows, it's just not to my taste. I bought the plans because I like the 5 panel hull shape and massive displacement/load capacity, figuring it would not be too hard to change the shape at the ends. Worst case scenario, I paid the BBC crew back $30 towards countless hours of research/entertainment here, and move on to another set of plans.

I made a one-hour cardstock/posterboard model in 1/4 scale to see if I could read/interpret the plans and to gauge how I would go about changing the bow shape. Unless I got something way off (please let me know if you think I have!), the nesting appears to have exactly enough material left to un-reverse the upper panels without additional splices.

To change the shape of the upper panel, I used the same point that is the closest to the "top" of the plywood sheet, but instead of angling the bow cut line to the right and towards the "bottom," I tied it to the point that the baton used for the camber for the upper side/cut line (right hand side the way the plans are drawn) hits the edge of the sheet of material. Easier explanation: I added a "pizza slice" triangular wedge to the bow end of the upper panels. I left of the camber, but I'm not final on that decision.
CardstockBoatBow.jpeg
The "model" has wavy seams, but I believe that is mostly due to poorly placed pieces of clear tape... and some cats kept sitting in it :roll:
CardstockBoat1.JPG
CardstockBoat2.JPG
I couldn't work it out in the paper and 1/4 scale, but it appears that if I take the reverse curvature out, that will take out the tumblehome toward the bows, which will mean that the upper panels will have too much curvature at the seam with the chine panel as drawn in my modified plans. I don't think the difference is all that significant, but I think it will create a gap towards the middle too wide to bridge with the woodflour epoxy mix.

Before moving forward on this, I intend to build a full scale model out of some thin cheap material available locally. Just stitch it together, no glue other than to make the splices (I'll probably use somewhat narrow butt blocks, screws, and cheap wood glue so I can get it apart later). My idea is to initially draw all the original lines before cutting, then draw a second line where the upper points are moved ~2 to 12mm to the left. (ex 89 to 85, and 158 to 146 in the metric plans). This will leave some extra material to make adjustments while lofting the upper panels... I hope. It'll take some eyeballing to make sure I've left a relatively fair curve while adding enough material, so number are just an example.

Next step for me will be to spend the ~$100 at Home Depot on some underlayment or tempered hardboard to make a full scale model on which to make further adjustments and hopefully some full size templates. I want the full size templates so I can temporarily adhere them to the yet to be ordered Okoume and use a flush trim router bit to make copies. I still need a couple weekends over the holidays to re-arrange my garage before I start a full scale model. Hopefully can get some opinions or course corrections before I jump in.

Does anyone see any reason not to continue with this scheme? Beyond the fact that all I'm building so far is extra work.

Flush trim router bit to copy templates... bad idea?

I wasn't sure of the appropriate forum, let me know if I guessed wrong.

Sorry for the long winded first post and thank you in advance for any input or opinions.

Dougster
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Re: HC16 - Modified bow shape

Post by Dougster »

I can't visualize what your about but it's a good idea to make a model with cheapo 1/8" or so wood. I did that for the SK14 and it does help visualizing and understanding the process.

Dougster

JohnFixes
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Re: HC16 - Modified bow shape

Post by JohnFixes »

Dougster, I remember seeing your small scale model in your SK14 build thread; really nice looking. Like I would have that on the mantle.


I definitely spewed out my thought process without explaining what I was really trying to do.

I really like the function and waterline design of the HC canoes, the styling just doesn't resonate with me. I'm trying to get a more vertical upper panel and bow shape, almost like a store bought canoe, but without all the terrible flexy plastic that warps when you leave it in the sun. I'm a first timer, but I do know better than to deviate from the designed hull shape where it's in contact with water.

I'm not trying to re-create a Coleman canoe, but some reminiscent styling is good for me...
ColemanCanoe.jpg
Old picture from my wife's youth.

That canoe lives in the under porch storage of the now grown a** man shown in the front of that canoe. He said I was welcome to it, but I want to try my hand at building a small boat before I attempt a real powerboat build.

My wife feeling nostalgic once seeing the hull getting tied together is certainly going to make things easier going forward

Alext
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Re: HC16 - Modified bow shape

Post by Alext »

Hi. I use and recommend a finishing router (small 1/4 inch), way better than a jig saw.I make
the patterns out of MDF, using a straight 8mm router bit. It makes for nicely faired panels. I then
use a flush finishing router bit to cut the panels. Keep a sharp eye on the bearing, lubricate and
tighten. They tend to come loose and the bit will take a dive. I also use my CNC for anything smaller
than 80cm (3 feet). If I had the space I would make my CNC big enough to cut a whole sheet of ply.
Everyone seems to be waiting for some deep thought or emotion
Someone to get the devotion of what they do

JohnFixes
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Re: HC16 - Modified bow shape

Post by JohnFixes »

Alex - Gan xie. I'm planning on purchasing a router after holidays/before okoume plywood... likely going to be a larger 2.25hp, but I'll still go with smaller/finer 1/4" shank bits for this purpose.

I did make an incremental step:
PlywoodInTruck.jpg
Purchased the cheap/thin plywood from Home Depot for the templates and test cuts. Picture for posterity... it was the very first building material load carried in the newly purchased '23 Tundra and I'm thrilled it was for boatbuilding

Alext
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Re: HC16 - Modified bow shape

Post by Alext »

I’d strongly recommend the smaller finishing router.
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pee wee
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Re: HC16 - Modified bow shape

Post by pee wee »

Alext wrote: Fri Dec 09, 2022 8:22 pm I’d strongly recommend the smaller finishing router.
I love routers, I have five! I have two small trimmers, one medium size with 1/4" shank, and two jumbo routers for the big stuff. I reach for one of the small routers unless I have to use a big one. The production routers I have are just heavy and awkward to use if you have to hold them at an angle or a reach. My favorite out of them all is a Bosch Colt which came in a kit with different bases and accessories: https://www.amazon.com/Bosch-PR20EVSNK- ... JX202?th=1

I don't get much of use out of most of the accessories, but the basic router is just the right size and easy to use, and being smaller diameter it's easier to see what you're cutting. I think you can get one by itself for $89, maybe less if you shop around. If you find you do need a large router, then you'll have two- one handy one that you'll use all the time and one capable one for the grunt work.
Hank

Dougster
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Re: HC16 - Modified bow shape

Post by Dougster »

I'll give a second vote for the Colt router. I had a bigger one and hated it--jerked like hell when turned on, heavy, and generally scared me. Thing seemed malevolent, but that said I had no previous experience with one. The little Colt guy is much more manageable for me.

Dougster

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Re: HC16 - Modified bow shape

Post by OrangeQuest »

Most used router for me is an 18V Ryobi cordless. Easy to handle, small base but does a very nice job on flush trimming and round overs of corners.
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