'76 22 Osprey re-build

[Que Pasa]

OK, here's my transom skin layup. It is 3 layers of 1708, one layer of 1.5 mat. My tabbing schedule was 6, 10 and 18.

[Que Pasa]

So the area I'm concerned about is above the original skin where the melamine is. But I think I will fill it with a layer of 1.5 mat.

[RickK]

That looks good QP!
It may take more than one layer of mat - if you say it's 3/16" - to fill in the area above the old cutout. Cut the pieces to fit and clamp them at the top with spring clamps and flip them out of the boat.  Then roll the resin on, flip one layer of cloth back in and roll/hard roll that in place, then repeat until it's filled - all wet on wet.

[Que Pasa]

Quick question om\n gluing together a core of two pieces of 3/4 inch ply.  I know you guys are using mat and 1708 but are you using thickened epoxy?

[RickK]

This is what I did - 2 layers of 3/4" marine plywood with 3/4oz, 1708 and 3/4oz between them. No need for thickened epoxy between them, just soak them real well with resin.
Make sure you are going to "clamp" them on something that is absolutely flat.  Get the two layers lined up with the dry glass in between and then drill a "registration hole" the size of a dowel in the opposite corners of the material so you can tap an epoxy coated dowel into each corner to keep them aligned after you resin them up (Tip from DirtwheelsFL - thanks Chris) - they'll easily squirm around if you don't.  You could do this with a nail or screw but then you'd have a hole to fill - using the dowel, it stays in forever and you sealed it with epoxy.  Then pile everything you have to "clamp" the two layers together - I think I used 10 cinder blocks.

[Que Pasa]

Perfect Rick, I think I'll cut my crown pattern before I lam them together. !/2 rounded router bit good for the edges? What do you think of wrapping the inside face of the core with a layer of 1708 to seal it?

[RickK]

I left the edges square.  You might want to round over the inside edge where it will meet the hull side and hull bottom against the transom.
The inward edge of the core will be either against the hull sides, the hull bottom or under the new cap you're going to make, so it can be left square edge (make sure to fill the gap with thickened epoxy fillet all around the 3 sides when you glass the front of the core in)
As for the inside face (pointing toward the inside face of the transom), resin coat it and trowel (1/4"x 1/4" or 1/4" x 3/8" notch) thickened epoxy onto the inside face of the transom and clamp the core in.  That's all you need. 

[Que Pasa]

Filled in the area above the old skin with two more layers of 1.5 matt. I still have a 1/4 gap between where the cor will lay and the new skin. It seems that the 3 additional layers of tabbing are keeping the the core from sitting flush.

But I did get the crown cut and will glass my core tomorrow. Here's my crown of 1 1/2".

[CLM65]

Nice curve on your transom.  I made mine 1", and I think Carl's is 2".  I think anything in this range looks good .

[Que Pasa]

Yea Craig, curve looks good. Still dealing with the gap, guess I'm just going to pull it all together with clamping an hope for the best.

[RickK]

Do you have a straight edge short enough to lay from the bottom of the hull (inside) to the top of the extension and flat against the new skin?  Like a 2' or 4' level?  What does it show?  If the extra tabbing along the bottom and sides is holding it out do what Joel said and grind out the core a little.  If you see that you still need to build up the area above the old skin do that too.

[Callyb]

I don't mean this in a sh!tty way, but you are making this way more difficult than necessary. The easiest/most appropriate solution is to grind your core back to fit your tabbing. Filling that big of a gap with thickened epoxy will take up the gap, but thickened epoxy is fairly brittle and will end with a wavy outer skin (once you clamp).

To clamp and hope for the best on the transom isn't a good idea. This is the part of the hull that transfers ALL of theforces of the motor to the rest of the structure. If you don't have a solid laminate here you are going to have problems down the road.

Again, I would strongly recommend a different route than you are planning on taking. You are commuting a huge amount of time and effort into this project, you don't want to half-* any structural components. Please reconsider and make sure the transom is done correctly.

Please don't get upset with me over this post, I have only the best of intentions.

[Que Pasa]

Cally I did think about going that route believe me. My thoughts my were even if I ground out the core and it was no longer fare it too would create a wavy skin. Don't know about you, but I dont think that once that grinder hits the ply it will ever be fare. No offense taken I'm learning more and more as I go. I was going to leave the dam up and use the bolting method with 4x4's. Thanks for the thoughts and help. Also I cant be the only that has run into this.

[CLM65]

As someone who is in the midst of fighting non-fair outer surfaces, you really want to keep them as fair as possible.  I think this is worse than all the grinding I did.

[RickK]

QP, if I'm understanding you correctly, the entire core is standing off the transom a 1/4"?  And you think that the 3 layers around the perimeter is causing this?