Have a couple of cleats that had leaked and gone unrepaired by PO that I'm addressing now .
The original layup is outter gel/glass>Balsa>glass>plywood>glass
I've got the damage cut out and ground down to the outer glass layer from the inside ready to rebuild. My plan was to bed in 2 layers of 1/2" plywood (with 2nd layer being larger) with epoxy and high density filler, then cover with glass, and not using any balsa thinking the plywood would be more solid for cleat backing. Or should I go back to the original layup? Which is better, or does it really make a difference? Im thinking the balsa wont be as strong during sideways pull on the cleats. I have to purchase a 1/2 sheet of balsa anyways for another non load area repair, so I'll have the balsa anyways. I'm putting alum backing plates on when reinstalling the cleats to make it more solid.
Thanks

I would use plywood or just lay up the cleat area solid glass . 5 layers of 1708 would be more than sufficient . I would skip the balsa because it does not take the compression well when you tighten the mounting bolts for the cleats.

What TM said, use a piece of plate glass , layup , when cured it will come off plate glass , permanent marker your pattern and cut with cutoff wheel or metal blade jigsaw.

Is all 1708 epoxy compatible? Have a roll of this that I can use if compatible. Thanks

nearly all current fabrics are compatible with epoxy but you will have to work to drive the resin into mat side of the fabric and if your gonna use an 08 put it in with the mat side out. In other words bi-ax side is the bonding side with epoxy, mat tends to be wet and heavy and the disorientated weave is very weak in comparison to the directional uni layers. Mat gives weaker resins an interlaminate bond that is not necessary with advanced resin systems. You should be using a 1700 but for this project you'll be fine.

you want to be careful not to over build the area, you dont want to end up with a hard rigid spot just around the cleat. try to taper off the rigidity if ya can, stagger off the ends of the laminate

A couple yds of 1700 is cheap. If that'll be easier to work with, I'm all in for that.
Have been using West Systems do to simplicity and availability,, but thinking of going to the 635 at a good amount of savings. Does the 635 have the same working characteristics as the WS?
Thanks

If your going to use plywood then look into MDO plywood unless you are going marine grade stuff....
" MDO is produced with a high-quality thermosetting resin-impregnated fiber surface bonded to one or both sides under heat and pressure to create an exterior-grade plywood panel. Specially selected veneer directly beneath the fiber overlay provides a smooth surface that is ideal for painting. MDO is manufactured with waterproof resins that meet or exceed all veneer-grade, adhesion, and construction requirements. Sign writers find MDO is ideal and the panels of choice for Exterior Signs"

I used this stuff to rebuild my cockpit wood and its real nice to work with and super straight...cuts like normal wood but has some good density for screws and such to have a good bite into.....ive had some scrap pieces outside behind my garage for close to a year and they still look like new other then being dirty...i found it at my local Menards..they have it in 1/2" and 3/4" sizes...

yes 635 is very similar, actually easier to work with. West is a great product and of the highest quality but is way over priced for what it is. Because you are also potentially laminating upside down toss a bit of Cabosil in the resin to tighten it up and help hold things up there. Yes 1700 is WAY easier to wet out and work with plus it is technically correct for what you are doing.

1 more question, Do I build up the layers with just the 1700 on top of each other? I thought mat was needed between cloths, unless thats for poly use?

This repair area is now done and solid. It’s up inside the gunnel underneath side, done with 635 epoxy/1700 and will not be exposed to sunlight, weather, anything. Does it need to be topcoated with paint or can I leave it unfinished? It will never be seen again unless interior compartments are removed for repair, by next owner. The complete hull has been gel coated when built. So figured might be a reason?????