Hello. I am cutting one of your trappers out and I was wondering. Instead of using butt blocks do you think it would be strong enough if I just cut 10" fingers into the edges of where the panels join of each piece ( set on dove tail jig ofcourse ) and epoxy and glassed that together? If so, how many fingers do you think would be best I cut? 3 - 6 probably somewhere in there?
Well there's an issue with that: If you cut the fingers in the plans as drawn, you'll shorten the overall panel length because the fingers will slide into each other when joined instead of just butting up against each other.
If you decide to do it anyway, I can't promise the panels will align or that it won't look a little funky.
I just finished a touring pirogue tv. I drew the centerlines in and cut the wood as long as the panel would allow.
Then I lined up the center lines and did the QA measurements, clamped the pannels together and cut them together with a wavy line instead of straight through the center line.
I figured this would give me a little more surface to butt glue them together with. After they dried I sanded and glassed the seams. Held up pretty good so far. The sheets would not really allow a "10" fingers" on my design, there is not enough spare wood past the center line.
I have seen photos of larger boat kits that join their panels end to end the way you are describing. Like Matt says you got to keep the center line where it is in the plans. If you can do that I think it would be a great joint. You would want to weigh down the whole thing nice and flat while the glue dries.
I guess the other problem would be if you had too perfect a cut through both pieces and they fit too tight there would not be much room for the thick wood flour epoxy mix. My wave cut allowed plenty of glue space but eh pieces fit like a glove because they were cut together. Also each side was unique so there was no mistaking them once i decided which side was in and out.
I am not trying to be a kill joy , but why go to all that trouble when a normal but joint with glass on both sides is a proven
joint that is tough and simple.
Ron
All I have ever used is the butt joint and I try my best to get it as tight as possible so when it is joined there is a line less in width then a pencil mark. I have been known to even give the edges a light sanding at a slight angle so they fit tighter when together. One sanded ( or undercut ) towards the bow and the other from the top towards the stern. About three passes with the sandpaper does the trick since I use very thin wood. something like this ....Bow-----//-----stern. It smooths the saw cut on the wood and gets rid of any roughness.
The epoxy gets in there and then it is covered with a strip of glass on both sides , the glass is about 4 to 5 inches in width on both sides. After the boat is together then it is glassed inside and outside so that makes for two pieces of glass over the joint........ One narrow one over the joint and one covering it and the boat.
If I do everything right the joint is almost invisible , well not really pronounced.
Remember:
Amateurs built the Ark...... Professionals built the Titanic
Visit some fine paddlers at The Southern Paddler
I try my best to get it as tight as possible so when it is joined there is a line less in width then a pencil mark
Thanks Sparkey. You have answered a question that has nagged me about my next build. I cant see why you need a big ugly jion in the middle of the boat. I am sure that a thin epoxy bond is just as strong as a thick one and this is backed up with the fiberglass anyway which has got to be stronger than the ply.
It takes more time to do it my way since I fasten the wood down to the work area , then epoxy saturate it when it is together making sure that joint is wet. The next day I add the glass to one side and the following day to the other side.
Just make sure you do not epoxy the panels to your table , some plastic under the joint saves a lot of work.
Basically it takes me three days to do what most folks do in one day. I figure the preparation and getting it together is the main part of making a boat and when it is together then that is the icing on the cake for me because I can go nut's with modifications on the deck , trim and the rest. That is the fun part of the build for me since I know the hull is the way I wanted it.
Remember:
Amateurs built the Ark...... Professionals built the Titanic
Visit some fine paddlers at The Southern Paddler
I guess the reason I go through extra pains to make butt joints is purely in my head. This is the third boat i have built the first two I ground a nice long scarf joint on end to end seams. This time I did this wave cut thing I came up with on my own. It is just a matter of wrapping your head around the fact that a simple straight cut butted end to end is perfectly fine covered with glass on both sides. I just do not want a block over that seem inside my boat.
Just hard to imagine 5mm ply snugged up against another piece is very strong. You are right Tx river rat it is proven and it works. Just need to build a couple more and prove it to myself. My current build stretched the boat to 19' 1" so I got lots of but joints they are all inconsequential. I am of the belief it is the glass that makes the boat not the wood and the butt joints do not make much difference.
) and epoxy and glassed that together? If so, how many fingers do you think would be best I cut? 3 - 6 probably somewhere in there? 
