Guideboat Framing

[Placid Paddler]

Hello all. New to the forum. A little background, I'm finishing up a kevlar and glass canoe, but it is too cold for epoxy work, so I'm just waiting until spring. The kevlar canoe has been a fun build, but it has taken longer than I thought and I'm also realizing that epoxy work is a PITA. I bought Jeff's first book last spring and read through it, but originally didn't think it was my thing.  Well after mold making and epoxy I've changed my mind and my guideboat will be SOF.

 

My question is about frame spacing and plywood thickness. I originally transfered the measurements from the book "Building An Adirondack Guideboat" into a CAD file planning to make another Kevlar boat, so I have 16 stations spaced ~10" apart. The boat is 16 feet long. Using the method outlined in Jeff's book I assume I could throw out half of those stations and make 8 frames spaced ~20" apart made of 3/4" baltic birch. So the question is should I do 8 3/4" frames or stick with the original plan and use 16 3/8" frames? Which method do you all think would be most structurally sound? Should I go even thinner (I have access to any thickness of BB)? etc. Extra cutting and lashing time would not be an issue for me.

 

As a side note for Woodman, I am also in the KC area and I called Metro Hardwoods in Independence and they have a wide selection of baltic birch plywood in 5x5s and 4x8s. I don't know if they will be cheaper than Liberty Hardwoods though. I'll post a picture of my plans here, and if anyone is interested I can send you digital copies that can be printed on a plotter.

 

Thanks.

 

[Kudzu]

I usually only answer posts that are related to my boats but I have always been interested in the Guide Boats so I will make exception. 

 

As for frame spacing the answer is it depends.   You need to settle on the gunwale and stringers sizes first. They provide a lot of the strength and rigidness of the frame. Too small the frame will flex to much.  Also you have to be careful to get their shape right. If you try to force the larger stringers like the Gunwale into a bend they don't like they will try to return to their original shape. I learned that the hard way and my canoe 'hogged'. That is the keel is slightly higher in the middle than the ends.  I had to do a lot of research and homework to figure out how to get around that. 

 

I would aim for the wider frame spacing because the frames protrude inside the boat a good bit and they do clutter up the inside of an open boat. My frames spacing can range from 12" to 30-32".  20" to 24" wouldn't be a problem.

 

As for plywood, when you start installing stringers, especially the gunwales, there is a lot of force pushing the frames inward so you have to put a brace across at least a couple of frames to keep them from distorting or even breaking. 3/8" wouldn't be as strong and could take a lot of bracing. It could work but I would just use 1/2" and keep the spacing around 24". There there is a possibility that will need a thwart too, but if you are putting in fixed seats they should work instead of thwart.

 

I think it is an interesting idea and not trying to be discouraging, just want to point out there is some planning to be done before you jump in. And the first one may have some issues that will want to work on.

[Kudzu]

I was looking at the enlarged view of your drawing and thought of something else. You have the lovely hollow shape in the bow where the frames take an inward curve. The fabric is not going to take that shape. It will take a straight line between contact paoints so you will have to revise your frame shapes to better suit the method. Stringer placement will be important.

 

I did a Wineglass transom on my rowing boat. I was told I couldn't do it but I had thought it through and knew how I could get the shape I wanted. The classic boats have a hollow like you show and obviously mine doesn't but it looks very similar. Just had to think differently than traditional woodworking.

[Placid Paddler]

Thanks for the replies Jeff. It will be a challenging design, especially for my first SOF. I really should start with one of your designs, but I already have a canoe in the works and I have never liked kayaks (blasphemy around here, I know). The issue with skinning the hollow cheeks was going to be another question of mine, but I was planning on asking somewhere else where they have made SOF guideboats before. I like your method of framing so thats why I asked that here. Here are some links to other SOF guideboats where they managed to skin the hollows.

 

http://s1229.photobucket.com/user/guideboat/media/26Done.jpg.html?sort=3&o=3

 

http://www.capefalconkayak.com/adirondackguideboat.html

 

Also, thanks for answering questions about a design you aren't affiliated with. Maybe after the kinks are all worked out, and I have a more complete set of plans we can put them in the next book "How Many More Fuselage Frame Boats Do You Need?". Your second book should be arriving at my house soon, so I will have much more reading to do, and I might just end up making your rowboat first to get the hang of things. I can always tell my girlfriend that I made it for her. Whatever I find out about the hollows I will forward here in case anyone is interested.

[Kudzu]

When I said hollow, I was referring to the section of the hull where the hull shape is concave. Skin just will not do concave unless it was glued in place. If you look at you plan you will see where I drew the red lines on 3 frames. This is the shape the skin would want to take.

 

BTW. the green boat photos, I think those are from a client of mine.

[woodman]

Hello fellow KCitian...Skin Boats, you gota-love-m.... They are awesome...

[Placid Paddler]

Jeff, the green guideboat is from one of your customers. I came across it over at the wooden boat forum. I talked to Brian at Cape Falcon Kayaks who has built a few SOF guideboats. Here is what he had to say about the hollows:

 

"The lines are usually only hollow in one plane.  Fore to aft the lines are straight, meaning that they conform a lot better than you'd think,  a few spots just barely don't touch.   Water pressure takes care of that though."

 

so I think it can be pulled off without too much deviation from the historic lines.