Are there viable alternatives to scarf joints (sounds like a pain and imprecise in my unskilled paws) and butt joints (doesn't seem very elegant)? Tongue & groove? Finger joints? Biscuits? If there are good and obvious reasons why these won't work, feel free to pile on. I have a fairly thick (3/8" :lol: ) skin. The only limitations I see are 1) finding router bits that will work on thin-enough plywood and 2) using plywood with solid layers. Then again, you can fit what I know into a thimble. Am I way off?
Joint alternatives?
- Thread starter captcj
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Scarf joints hide the seam really good , butt joints show the seam. If I recall correctly ... you are building , or thinking about doing a U.J. Pirogue and want to paint the outside. Anyway you were asking about it in a different post. :?
The paint will make the seam vanish on the outside and on the inside the center rib is just that .... Center ... so it hides that seam and no one sees it. :wink:
OK... I might of been napping at the start of your questions about building boats but ya have to remember a lot of us older folks have a short memory and that was a day or so ago. :lol:
Chuck.
The paint will make the seam vanish on the outside and on the inside the center rib is just that .... Center ... so it hides that seam and no one sees it. :wink:
OK... I might of been napping at the start of your questions about building boats but ya have to remember a lot of us older folks have a short memory and that was a day or so ago. :lol:
Chuck.
I like the way your thinking. Toung and grove? That just might work. Might be as much work as a scarf joint but should hold strong. Just lay glass over both sides of a joint that was just butted together with a fitted castle wall type pattern should work like a charm. I think I may just try something like that on my next project......wich may be within the next 60 days. HmMMMMMM ya got me thinking
I too thought scarfing joints was going to be a pain.I have done it on two boat builds with great results. It was a lot easier than it sounds.I did mine with a belt sander with 80 grit paper. Just put a piece of scrap below and above the panels to be scarfed measure your scarf widths and clamp to bench. The lines in the plies will help to guide you.
Cappy,
Have you looked at Matt's method posted on the JEM forum?
I thought it would never match the appeal and strength of a scarf, but I now feel like the "skeptic who visited the chiropractor"....
I Stand Corrected!
Matt's butt joint method is quick, strong, and attractive. I'm going to have him show me how to achieve those same results next time I pick a wife! :lol:
Lee
Have you looked at Matt's method posted on the JEM forum?
I thought it would never match the appeal and strength of a scarf, but I now feel like the "skeptic who visited the chiropractor"....
I Stand Corrected!
Matt's butt joint method is quick, strong, and attractive. I'm going to have him show me how to achieve those same results next time I pick a wife! :lol:
Lee
Tongue & groove or biscuits in 1/4 inch or thinner plywood would seem to me to be much harder than a scarf joint. A finger joint would work and at least one kayak kit maker is using dovetails or something similar, but I'll stick to the butt joints for now.
Cappy: No, I haven't looked at butt joints on JEM forum. Perhaps a butt joint is not what I think it is. I will check that out. :?
Jimmy: T & G might be a challenge on 1/4" due to availibility of a router bit to work on that thin stock. I've seen T&G bitsets for 3/8". If the proper bits can be found, it would be extremely simple. One pass with the router down the butting edges with the right bit, cut out, slather on the epoxy, slide together, clamp and apply downward pressure over the joint (with a flat weight or a piece of scrap ply clamped down) to keep it all flat.
Remember, I don't know what I'm talking about! :shock: It just seams easier and more precise to me. An epoxyed T&G connection would certainly be strong.
Jimmy: T & G might be a challenge on 1/4" due to availibility of a router bit to work on that thin stock. I've seen T&G bitsets for 3/8". If the proper bits can be found, it would be extremely simple. One pass with the router down the butting edges with the right bit, cut out, slather on the epoxy, slide together, clamp and apply downward pressure over the joint (with a flat weight or a piece of scrap ply clamped down) to keep it all flat.
Remember, I don't know what I'm talking about! :shock: It just seams easier and more precise to me. An epoxyed T&G connection would certainly be strong.
Sorry, Lee, I wrote Cappy but meant you. :?
:idea: Now that I think about it, I wonder if the 'male' side, the 'tongue, of the T&G would be likely to crack when bent, since it would probably only be about 1/10" thick, on 1/4 ply. But then, the seam is going on the part of the hull with the least bend, so maybe. :?:
I guess it's time to wreck some plywood!
:idea: Now that I think about it, I wonder if the 'male' side, the 'tongue, of the T&G would be likely to crack when bent, since it would probably only be about 1/10" thick, on 1/4 ply. But then, the seam is going on the part of the hull with the least bend, so maybe. :?:
I guess it's time to wreck some plywood!
No joint is easier or more accurate than a simple butt joint. I've never heard of a butt joint failing in use - even hard use. You can reinforce a simple butt joint with either a couple layers of fiberglass on each side, or a plywood reinforcing block on the inside and fiberglass on the outside. Either method will produce a joint that withstands normal use, misuse, and abuse.
ANY OTHER TYPE OF JOINT WILL AFFECT PANEL LENGTH (both individual panels, and joined panels) AND OVERALL CONSTRUCTION TECHNIQUES.
I advise you to employ the kind of joint that you want, but must also inform you that you are working to solve a problem that simply doesn't exist.
ANY OTHER TYPE OF JOINT WILL AFFECT PANEL LENGTH (both individual panels, and joined panels) AND OVERALL CONSTRUCTION TECHNIQUES.
I advise you to employ the kind of joint that you want, but must also inform you that you are working to solve a problem that simply doesn't exist.
CJ There are two types of butt joint. One is just a piece of the same thickness usually about 8 inches wide overlapted equal amounts and gluied on to what will be the inside. Depends on what kind of boat you are building probably wouldn't work on UJ pirogue because of internal frame.
The other uses firberglass on both sides and Matt has a good tutorial on the jem site. I am not sure if the T & G would work well unless it was fiberglassed on both sides. The butt block methods spreads the force out over a greater distance same as a 8 to 1 scarf.
Russ
The other uses firberglass on both sides and Matt has a good tutorial on the jem site. I am not sure if the T & G would work well unless it was fiberglassed on both sides. The butt block methods spreads the force out over a greater distance same as a 8 to 1 scarf.
Russ
Digger, my butt joints are all reinforced with plywood about 2" wide. 8" is, in my opinion, a lot of waste. Once the joint is as strong as the parent material, any more is just excess weight.
You are probably right Jack. I was going by plans i've seen. I don't normally use them. I prefer scarfing but recently put a 8 inch butt block in a jem pirogue according to the plans. I felt it would stiffen the bottom and prevent oil canning in that aplication.
The boats I make have the joints reinforced with fiberglass , I epoxy saturate the wood and then place a 4 to 5 inch strip of glass over the joint. When it cures then the other side so both sides are glass reinforced. The part extending past the wood is trimmed flush with the wood.
I prefer the glass over wood since the wood creates a bump on the inside of the boat and I like a nice uniformed , flat inside on my boats. Plus it is easier to glass over that glass then a chunk of wood in there.
Made boats both ways and only one has the wood reinforcement all the rest of them are glassed. Actually double glassed since the joints were glassed and the whole boat was glassed.
Chuck.
I prefer the glass over wood since the wood creates a bump on the inside of the boat and I like a nice uniformed , flat inside on my boats. Plus it is easier to glass over that glass then a chunk of wood in there.
Made boats both ways and only one has the wood reinforcement all the rest of them are glassed. Actually double glassed since the joints were glassed and the whole boat was glassed.
Chuck.
Just use the butt joint. You won't be sorry. The strength you are concerned with is going to come from final glassing of your boat anyway.