Hi everyone, I'm just getting started.  I've gathered all the tools, read Fletcher's book about 6 times (so great), and read quite a lot of these posts (also great).  I've decided to build a 17x54.  Went to the lumber dealer in town, and decided i'm definitely going to use the Hydrotek BS 1088 6mm for sides, and 12mm for floor.  I'm going to use Mahogany for the Stem.  I'm planning to use Port Orford Cedar for the frames, and was thinking i'd match that with White Oak for the rails/chines.  I hope to have the boat for the rest of my life, and while i want it to be the most beautiful boat ever built, I truly want to use materials that will last and be effective.  So, first question... Instead of White Oak, anyone ever use Port Orford for rails?  It seems like the color would be similar to White Oak, but i wonder about durability as a rail.  appreciate any insight you might have.

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Looks like it mostly split in the glue joint?  Not enough prep (scarf not rough enough) or did you use heat to bend the gunnel and heat weakened the epoxy?

I'd try slipping some 60-grit emery cloth in there, rough it up, add glue and try to get it set again.

Or if you haven't yet cut it for length, glue the crack, kerf right through the scarf and glue over.

Yep, I think you're right Shawn.  The back story is that it is the inside rail and I clamped it in the bent position along the frames, but not fully seated against the frame -- because I hadn't cut the length yet it was tilted away from the frames.  I ran out of time, and left it... came out in the morning and it split along the glue joint. I'm not sure if it would have done this if I had fully seated it against the frames.  But clearly i needed better prep on the joint.   Also, you can't see it but it has a pretty good crack across the grain in a spot. Unfortunately, the total length of the rail is short enough that i can't remove the 8 inches and re-scarf, it leaves me about 3 inches too short.   

That's what I'm saying.  Glue it enough to glue the split.

Then saw right down the scarf joint.  Should only lose ~1" of length for a 1/8" cut.  this would give you clean scarf faces.

White oak is dense, so there's not a lot of porousity.  Definitely want to roughen it.  You can also use a heat gun to really open the pores of the wood and make the wet out epoxy coat runny so it gets in.  then cabosil or cabosil/kitty hair in the joint.  I like a little bit of kitty hair because it keeps the joint from clamping perfectly tight and prevents squeeze-out...or a piece of glass in there will do the same thing.

I see what you're saying, except check the image below.  This is why I think i need to re do the whole section.

If it makes you feel better, this happened to me last night.

3/8" WRC laminated to 3/16" jatoba.  The cedar was about 20 years old and DRY.

63705

So I slathered it with epoxy and clamped it well.

63708

totally up to you on how to fix it.  If you replace it, it can then be visually perfect.  If I were building for a customer, I'd replace it.

If you fix what you've got, you'll see the fix, but IMHO can repair it to still be strong.  This will be a personal boat to be used heavily, so I just went for the repair.

We are our own worst critics.

Honestly Shawn, that did make me feel better.   

and, yesterday i confirmed the weak link in my system.  

Was installing inside rail #2 (after Rail #1 broke a few days ago) and while still fully clamped, literally just slid it against the transom perfectly after repeatedly sanding the end for the perfect fit.  30 seconds later discovered that the scarf joint had broken apart on this one too.  

I didn't completely lose it, but I did empty my entire cache of curse words.

After a couple hours of whiskey by the fire last night, coupled with your image above... Here's my plan:

since I had perfectly completed the fit, and it is a cleaner break than the last one, i'm going to try to salvage rail #2 per your image.  Rail #1 i'm going to methodically "glue up" the new half to the old half.  I'm going to pay far more attention to my technique, because this appears to be my weak point.  I think the joint was starved because i didn't apply the thin first wetting coat.  I don't think i over clamped it, i just think the wood may have drank up the one layer i did apply.

I also discovered one of my frames has begun to split.  So I may need your help with a solution there too. 

rough few days. 

At the risk of telling you something you already know, here's a process that works. 

1. Cut the scarfs and roughen up the contact surface a bit with 80 grit

2. mix up some epoxy and coat the joint

3. add some thickening agent to the epoxy to get a mayonaise consistency

4. clamp up, but gently

What kind of wood? Is it white oak?

Yes.

Maybe mating surfaces too smooth and too much clamping pressure?

Yes, I think too smooth.  Also, i may need to thicken the epoxy a bit, but i don't think i over clamped it.  

Ok, another issue has developed.  The frame below has a thin split that appeared.  It goes from the top down to the joint.  Any ideas how to stabilize it?

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