Filling old speaker holes

[76SeaRay]

Somewhere in this boat's life a previous owner decided to put speakers in the dash. So, holes were cut and those holes ran into structural supports. Fortunately the structural supports are ok and the PO stopped there. When I got the boat there were speaker grilles hiding the holes and speakers won't fit so I am filling them in before I do new gelcoat on the deck of the boat and I re-mount the windshields and hardtop. Looking at the pictures, I put in an exterior plywood backing (fiberglass into place) to partially fill the hole so it sits up inside the hole and flush on the bottom side, however, there is still a lot of filling to do on the top side. Should I just feather out the hole and then layer in cloth to build it up. Then skim coat it and sand out for gelcoat or should I add in another layer of thin wood on top of the backing plywood before glass? Thanks...

 

[kcassells]

So I hope I'm not too late for your reply. Alot a guys are still in their caves coming out shortly.
-Chamfer the edges back to a rough 45 deg edge more or less. Sand out the gelcoat 3-4 " off for the new glass bond.
Your application is correct. Soak wood with resin and especially the edges front, back and sides.
-You grade that depth of hole with add'l soaked pcs. of wood to get closer to reduce a build up. One on the other with PB, 5200 etc. 5200 will more time to cure cause it makes bubbles in the glass if not cured. Temps are the consideration. PB is my choice.
-You could fill that entire piggy hole with PB with a lot of added chopped glass. The glass is what makes the strength, not the pb.
-You will want to add at least 2-4 pcs. of glass over the rough opening until
you come flush. Sand flush again, add more glass again or pb if needed.
-Finish with COLD BEER and fairing. Fairing may take a couple applications to come smooth.
Post pics of your progress and questions.

 

[kcassells]

 

[Scott Danforth]

Use PVC proboard vs hardwood, then repair as above. Once cured, pull the PVC board out

 

[76SeaRay]

I already had the plywood bonded into place with epoxy and glass on the underside. I went ahead and ground out the area around the hole back about an inch to slope the existing fiberglass down to the plywood. I put in two layers of 1708 to build up the hole and topped that with a layer of polyester structural putty to level it out a bit. I was surprised how much it filled in with the two layers of 1708. This is my first effort with fiberglass and since it is up on the dash of the boat, I figured it was a good place to learn. That part of the dash was covered with a black vinyl appearance cover of some kind so it will get covered up if it doesn't look all that great from learning how to do it. I topped it off tonight with some white gelcoat with wax to cure it. Most of the gelcoat will get sanded back off as I level the holes and then skim coat them with polyester fairing before gelcoating the entire deck above the rub rails.

 

[76SeaRay]

So here are the pics after sanding the gelcoat. Does all the gelcoat need to be sanded off before applying fairing compound or can it just be covered?

Thanks...

 

[kcassells]

Looks great. Nah the gelcoat gives you a plane of filler like fairing.
The issue will be if you can get a gelcoat to match your weathered color. All good.

 

[76SeaRay]

I am actually going to sand and gelcoat the entire deck from the rub rail up. I had a friend help me match an RAL color code (RAL 9010) to the white underneath the rub rail since it isn't weathered like the rest of the deck. The gelcoat is due for delivery tomorrow but I have a long way to go with sanding before I can spray.