using 2 sheets of plywood for bottom and sides of boat

[Bryan Campbell]

hey guys I've got a quick question I'm building a skiff style boat I wanted a long one so i decided to see what you guys think i should do for the sides and bottom I thought about dovetailing the ends together would this work I'm trying to build a 12' to 15' long boat with 24" sides and 4' wide any suggestions I'm open for anything the boat needs to hold at least 500 to 600 lbs cause I'm a whopping 250 and I want to be able to have company in it with me

[Raggi_Thor]

You mean something like this?
http://www.oneoceankayaks.com/stitch.../Scarflock.htm

You can make this kind of joint on a flat floor before you bend the panels in place.

[Bryan Campbell]

thanks that seems more complex then i was thinking more like the joints you see when someone builds a dresser drawer or something like that

[John Perry]

I am not sure if you mean the joints between two sheets of ply forming a single panel, or between the sides and bottom of the boat? If the former then I think that a conventional 8:1 taper scarf is best for one off construction, the finger type joints are really for when a number of kits is being produced using automated machinery. Making scarf joints in plywood is not too difficult, you can taper a whole stack of plywood ends at one go by setting them up staggered and planing accross the ends with an electric plane. You do need to be very careful about alighnment when gluing up though, a scarf joint does not gaurantee alighnment of the panels like a finger joint does.

As for using dovetail joints for joining the sides and bottom of a flat bottom boat I think that would be a good method if you are prepared to take the extra time to do it. However, simple butted together joints temporarily fixed with copper wire stitches and made with a fillet of epoxy and usually reinforced with fibreglass cloth or tape, on the outside at least, have proved to be perfectly adequate. Try making up a scrap joint like this for practice then break it, with luck you will find the joint to be stronger than the adjacent plywood panel.

John

[JEM]

I've tried something similar to the Oneoceankayak site. That joint doesn't offer any more strength and are a pain to assembly. The biggest advantage to them is for panel identification. If you have a bunch of panels of similar size, that's helps ensure you're matching the correct one.

[Raggi_Thor]

Hmm, Matt, what do you mean "a pain to assembly"? I thought this would be easy if they are cut with precision...

[safewalrus]

I'd use a saw it's easier

[JEM]

I found that it was more fuss (and slightly more material) to ensure the seam was filled and no cavities present. I think it would also look a little odd if the hull was finished bright.

It's a technique that has some merit. I just disagree that it's any stronger.

My opinion based on personal experience.

[Bryan Campbell]

thanks guys this is all good information ill post some pics of my plans on here soon