What Material Should I Use For Backing Blocks?

While I have access to the inside of the hull, I'm going to create backing blocks for the cunningham/outhaul blocks plate screws and for the cam cleat hardware screws that hold those lines. See the photo below.



My first question is, what type of wood should I use? Oak? Marine plywood? I plan on covering/sealing the blocks ahead of time with resin and glass, letting that cure, then anchoring them in place with resin between the backing block and the underside of the deck and with a single strip of glass over the top that's resin-ed to the deck as well.

My next question is this. This hardware is currently being held to the deck only by what appears to be 2 layers of 1/16th inch thick fiberglass matt... with foam in between. Should I just leave the existing screw holes in the deck alone and use those 2 layers as well as my new backing blocks for anchoring the hardware? Or should I enlarge the existing holes and just use the backing blocks for anchoring?

Because, when you think about it, if you want the hardware to be fully sucked down on to the deck and only being anchored by the block, the current holes in the deck glass should be enlarged so they are bigger than the diameter of the screw threads.

And of course I'll seal everything up with silicone so the hardware is completely water tight.

Thoughts?

- Andy

The typical thing would be a piece of aluminum. If you got a piece of 1" x 1/8" or 1/4" and cut a couple of lengths off at least 1/2" beyond the bolt holes with a hacksaw. If the bolts are 2" apart cut the backer 3".

The jib tracks of big boats are backed with either 1/4" aluminum or 1/4" solid glass/epoxy.

You are simply making a big washer. The thickness is not important. The hardware store variety aluminum will by fine for the inside of a Laser it doesn't need to be marine grade.

I've fixed a bunch of these, once you make the repair it will last for years of sailing

all it takes is a small piece of plywood, either 1/2" or 3/4" thickness,

the piece can be as small as 2.5"x5", you could coat the wood with fiberglass resin but I never felt the need (as long as your hull isn't constantly filled with water you'll be fine)

if you drill a small pilot hole it will make it easier to screw in

they'll gladly give you small pieces of scrap at Home Depot, they throw them out

don't forget to glob some silicone or 3m in the screw holes, I usually dab a little in the hole and make sure the bottom of the screw is coated, it's worked well, never had a leak in these spots