1st post, looking for advice

[earle]

Well, may be able to make some headway afterall. Wife was able to score an awning from the rent-all that she does the books for, so I'm going to proceed, at least till Sat. night.
One final (hopefully) question occurred to me. If I proceed as planned and glass the bottom of the plywood BEFORE I glue it to the deck, will the wood still retain enough flex to contour to the shape of the deck? Standing on the trailer tongue last night I noticed the deck has a bow to it. High in the centre and bowed to the outer edges and sloping to the front. Not a deep bow, but still enough to make me realize the plywood is going to have to "give" to conform to the shape of the bow. Will it do so with the bottom glassed? As usual, thanks for input.
Earl

[smokeonthewater]

That's why I said to cut the ribs to the shape of the bow deck first, then attach them the the ply sheet, then verify that the assembly still matches the required shape before glassing it...

I would glass ALL sides if the new assembly before installing so it is fully sealed and simply needs glued in...

[SkunkBoat]

probably not. You might want to cut into smaller pieces so they follow the shape of the upper skin without having to bend them.. Not too small that you have a lot of upside-down glassing to do!

If you hold a firm straight edge across the inside you'll get a sense of where you need to have a "seam".

[scook]

No matter how big or small you cut the plywood, do what Smoke says - cut the ribs (little beams) to conform to the underside of the deck.

Doing this I'd called scribing. You either wedge the rib in place (just enough tension to hold it there) or have a helper hold it there. Since the deck humps up, the top ends of the ridge will be touching the underside of the deck and there will be a gap in the middle. Measure the gap, cut a small block of wood approx. 1" to 2" wide by the height of the gap and use it to space your pencil down from the underside of the deck. Holding the rib in place, mark the curve of the deck onto the rib, cut the curve in the rib and hold it back in place to test the fit - make adjustments if necessary and you have a rib that will make the plywood conform to the deck.

The rib has to be stiff/strong enough to hold a bend in the plywood without bending. Two things to consider: 1) plywood will only bend in one direction, not both directions at the same time (a compound curve). If this is a problem, you will need to cut the plywood - it probably isn't but you can tell easily. Drill,the holes in the plywood before you dry fit it to the deck - if you can't get it to go tight to the deck, that's probably the problem. 2) to make the plywood bend more easily, you can score the back (top surface, the side that contacts the deck) perpendicular to the direction you want to bend it. For 1/2" ply, cut a little less than 1/4" deep, 1/2" to 3/4" apart and feel how it bends. If you need a few more scores, you can add them. The resin,will fill the grooves and you'll still have a strong deck.

[scook]

Blasted automatic spelling - It IS called scribing, and the ends of the RIB will be touching.

[earle]

Originally Posted by scook

Blasted automatic spelling - It IS called scribing, and the ends of the RIB will be touching.

Good advice all. Cut the first piece this AM and rough fitting it now. Will start the scribing process shortly. I think the only "mistake" I.ve made so far, thanks to all the help on this forum, is assuming all I had to do was cut a couple pieces of plywood and stick em in place. Ha_ha.

[scook]

Yeah - just about everything about what you're doing is pretty simple in concept and REALLY difficult in the execution.

[phatdaddy]

take lots of pictures