Windlass Mount - GRP Strength

[ADMPRTR]

Hello:

I am trying to determine the number of layers of woven and roving Fibreglass to layup to support a windlass that is being installed into my anchor locker on a shelf.

Perhaps you can provide some direction for me please?

Here is the plan:

• The windlass weighs 48lb has a maximum pull of 2200lb: Quick® Italy - High Quality Nautical Equipment

• There will be two sheets of 3/4" spruce plywood on the top

• The motor will be enclosed on three sides and the bottom with a single sheet of plywood (each)

• The back side will remain open to maintain access to the motor

• The plywood will be sealed in epoxy to prevent water intrusion

• The structure will be fibreglassed using West Systems epoxy to the floor of the anchor locker and to the underside of the deck on one side

• The anchor locker floor is composed of roughly 1/4" of GRP over plywood

• The deck consists of GRP and balsa core and at the point of contact is about 6" from the gunwale

I have determined that GRP has a tensile strength of 300MN/M2 but I don't know how to translate that into the number of layers that I need to layup. I figure I need to target the maximum pull of the windlass at 2200lb.

To help with visualization, I have sketched in the proposed mount into a picture of the locker and also with the final product will hopefully look like.

BTW, the locker cover will be cut in half with the forward section being semi-permanently affixed.

Thanks for any guidance you can provide.