CONTINUOUSWAVE

I am relocating a new electronic unit on my 1987 Montauk center console, (The new device will not fit where the older, smaller unit is located.)

I'm looking for recommendations or reference links on a good way to fill in the bracket mounting holes (two screw holes and one one-inch diameter hole) left behind in the old location.

Cut a piece of mat larger than the 1-inch hole and glass [the mat] over the back of the hole. After [the resin] sets, cut circular pieces of mat and glass them into the hole until flush with the surface. Then cut another piece of mat and glass that over the top of the filled hole. A day later grind and sand the patch flush with the surface, then cover the patch and the screw holes with bondo. When set, sand flush and smooth. Then finish with gel coat or paint.
rich

To fill unused holes left from removing small screw fasteners, fill the holes with some epoxy resin mixed with a filler. If the holes are unusually large, use some soft pine dowel rod cut to length and shaped to fit to fill the hole, and use epoxy resin mixed with a filler as an adhesive.

To fill a 1-inch diameter hole in a instrument panel, cut a suitable diameter wooden plug from a scrap piece of marine plywood. You can use several thinner plugs to fill the hole if you don't have plywood of the proper thickness to make a single plug of the necessary depth. If the plug fits snugly into the hole, use your favorite waterproof wood glue as an adhesive. It the plug is a loose fit, use epoxy resin mixed with thickeners as an adhesive.

I am assuming that the instrument panel has a gloss gel coat finish. To repair non-structural flaws in the gel coat--which is how I would characterize the holes once they have been filled with thickened resin and wood--follow the repair instructions given in the REFERENCE section. See

http://continuouswave.com/whaler/reference/

Browse the TABLE OF CONTENTS listing to the REPAIRS-MODIFICATION subheading. Read

Repairing Hull Damage the Whaler Way

INSTRUCTIONS -- HULL PATCH KITS

If you plan to restore the gel coat finish in the repaired area, and you used epoxy resin, be certain to take the recommended precautions for top-coating epoxy resin with gel coat polyester resin. You must allow the epoxy resin to thoroughly cure, apply some post-cure heat to the repair to ensure total curing, and wash the repair with detergent and water to remove amine blush. If these methods are not followed there may be problems with the top-coat polyester resin failing to cure properly.

jimh, at this point in time because the original poster never stated it, we don't know if there was plywood backing behind the bracket holes. If there is not, the console may only be 1/8 to about 3/16" or more thick and then dowel method won't work. A solid fiberglass patch always works, anywhere.
rich

Also, because this is not a structural repair, don't use epoxy, because of the extra cost and labor as stated in the above post.
rich

Rich - You nailed it. There's no wood backing where the repair is needed. I'll use layers of fiberglass to make the repair. Thanks to all.