Glen-L.com

I was wondering, and forgive my rookiee question as I am certain it must have been asked before.. but out of curiousity... has anyone laminated some plywood to the backside/inside of the chine like its recommended for the keel?

I was thinking using a slightly thinner 3/4" stock lumber + 1/4" plywood backing epoxied together before its installed. The chine should still retain its screw holding and fairing properties right? Wouldn't the plywood backing help keep the material from spliting/cracking.. or not?

I'm curious.. as it seems Chine splitting is not exactly a rare event.

Logically, I don't see a problem with that,but I would laminate in place,not before.

If you laminate your chines/shears from multiple pieces of solid stock instead of just one thickness, you have essentially made plywood although the grain crossing is not as pronounced.

We laminated 5 ply 1/4" marine plywood to the Douglas Fir frames, doubled keel and chines. As Warren says, laminate in place after the chines have been sprung, before the hull ply goes on. Added insurance if the wood members ever split ! Apply several coats of epoxy to seal the plywood edges.



Click here to see the photo in context.
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Paul Kane Chelsea, PQ

Building the Glen-L Hot Rod : http://www.boats.chelseacoachworks.com

I could be wrong but I'm not sure you would want to laminate the ply to the chines after the chines are in place. Wouldn't that put the ply on the outside (sheeting side) of the hull and I suspect it would make fairing more difficult. I think if you want to do this lamination you would have to apply it to the chine before the chine has been attached to the boat.


Maybe it would make no difference at all when fairing which side of the chine the ply is on
Just my 2 cents.

Sorry if I wasn't clear enough, but the ply lamination is fitted from the inside, between the frames after the chine is sprung. It's very subtle, but if you look at the pic, the laminated chine matches the Sapele sides. Prevents splitting and evens out the colors ...
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Paul Kane Chelsea, PQ

Building the Glen-L Hot Rod : http://www.boats.chelseacoachworks.com

ahhh, sorry Paul I missunderstood. What do you think the problem would be, if any, if you laminated the chines full length with Ply, as I think Iggy is suggesting, and then installed them? Do you think it might make them too stiff to take on the correct shape when sprung?

Duane,That's my take on laminating first, that the chine would be stiffer to bend around

I meant instaling a layer of ply,then the solid chine next so the ply is on the inside of the boat

That's the fun with boatbuilding - no fixed way of doing things !

Our thinking was that the ply fitted between the frames would prevent them from shifting in the horizontal plane if the chine split or the chine fasteners ever snapped ...
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Paul Kane Chelsea, PQ

Building the Glen-L Hot Rod : http://www.boats.chelseacoachworks.com

I was thinking of cutting down the thickness from 7/8 to 5/8" than laminating the 1/4" plywood on the inside before the bend. I can only imagine how it might flex or what kind of strength it might have.

I could laminate between the frames on the inside... but I was hoping to reduce the odds of the chine splitting at the frames as well as in between.

I don't have a lot of extra lumber to experiment.... I have sufficient to do the chines a few times if I had to.. but if laminations are less likely to fracture, and chines seem to be a big culprit for fracturing.. I was curious if it might not be a bad idea to mix it up a bit?

I am a complete newbie.. and I will likely just do the traditional method on my first boat unless someone else has tried this and knows how it performs long time. Better the Devil you know sometimes.. right?

IF I were to do this I think I would take my chances with laminating first and then install the chines. If you want to install the ply first on the boat and then instal the chine I think your going to need to use a slow hardener for your epoxy so that it wont go off before you can get the chine bent into place. This is my concern. If you have any issues what so ever getting the chine to bend into place your epoxy might go off before the chine touches the ply. This is could very likely just be me over thinking these things. I tend to do that.

BTW Iggy the shears are also a part that many have had issues bending into place. It might be another candiate for a thin ply lamination.

Paul, I like the idea that the frames are "keyed", so to speak, into the chines. good idea. I'm not sure that will help with spliting issue but if anything did ever come loose it would help keep the frame it place.

Don't know if I'd do this or not...in retrospect, sounds like a good idea...but, I think my current problem revolves around the screw in the forward frame and not the amount of tension.

3/4 bends differently than 4/4 as well as kiln dried/green, heart/sap, vertical/horizontal grain, species of wood (oak/mahogany/DF/SYP)...a lot of variables.

Remembering the amount of push it took to get the chine home caused me some concern when I drilled that screw hole in the forward frame. So the fault, I think, is mine and not the idea, plan, or ability of the wood.