Mixing Wooden Boatbuilding Techniques

Mo,

Thanks for your comments, they're very helpful.

Regarding the trim balance, I'm going to design it with trim interceptors and LCG/LCB quite well aft, with the interceptors giving me some trim control. I've deigned a ball screw adjustment mechanism with a little knob for adjustment at the top of the transom.

Broaching is my biggest concern. I'm prepared to have the spray rails develop into a small fin aft if it turns out necessary. but I hope it wont.

Some of the inspiration for this design comes from the boat below - it's a brand new 'state of the art' rescue boat for the Dutch Rescue service KNRM. Looks like they saw Moe in 505 and thought 'I want one of them', haha.

 

Hi Andrew,

I am working on something similar, but want to go fully developable.
Simply because of the ruddy white elephant cnc router standing in my workshop.

I have to justify the thing somehow...
My boat will be in the region of 4600, with a beam of around 1800. Sharpish entry, and say 15 degrees deadrise. Trying to achieve some sort of balance between speed and seaworthiness.

On the subject, I do not know if this helps, but look at the structure of Grey Wolf. John Fox did the structural design, and if I recall it was stripped in western red cedar, and then laminated inside and out with ud glass lying at 90 degrees. That is an awesome boat by any standards...
Will see if I can find pics.

 

Hi Andrew,
My attempt to post has gone awry.

Have a look at Rodger Martin's Gray Wolf, which has strip construction sheathed with transverse ud glass inside and out. Very nice boat, and I think McNaughton has given the method a name.

BTW I am working on something very similar to yours, but fully developable panels.

 

Have you determine undevelopable planks by analysis? The description also fits plywood shaped using conic sections which will develop.

Developability also depends on plank width as I found when adapting a classic canoe design by J. Henry Rushton. I noted the bottom and bilge planks were parallel for their entire length so i merged them into a single plank, thinking Rushton would have done the same if he had access to marine plywood. Bad mistake . . . Bending force appears to increase as the 3rd power of plank width.

Mixing plywood and strips is fairly common. A nice sailboat is shown in this link which uses the method although it has a flat bottom, like the canoe that is the subject of the thread.

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