FInishing caulk?

[yobub]

I have two speakers in the transom of my 400DA, and I noticed that the bottom part of the fiberglass splits into two parts and has a gap between, that was cored at one point. From about the middle of the speakers up it's a single piece of fiberglass, middle of the speakers down, and to the interior the fiberglass splits into two pieces with a gap.

Given that the speakers are outside and not fully sealed, I filled the space with balsa coated in epoxy, and did my best to fill with epoxy but I'm sure I'm not going to get a perfect seal.

I'd like to use something to seal the edge to give a good, full seal with no gaps, but that also will present a reasonable cosmetic finish when it's done, even though it will be hidden behind the speakers. I thought about 4200 or 5200, but I'm really looking for something that will cure solid rather than flexible. Maybe I need to get over that.

Ideally, I would have something that would go in as a putty rather than a liquid to it doesn't run, but would fully harden like an epoxy, be sandable, but have a nice clean white finish.

Any thoughts?

 

[Lazy Daze]

How wide of an area do you need to fill?

You could use thickened epoxy - thicken it to a peanut butter consistency. Use just about anything you want to thicken it - you don't have to get special "low density" filler (makes it easier to sand), although you certainly could. Fine sawdust would do the trick.

Another easy thing to use is PC-11 past epoxy. It's like Marine Tex, but less expensive and easier to use.

PC-11 is close to white. The epoxy could be tinted. Or, either can be painted to match. I took a small piece off my boat and took it to an autobody shop to get color matched paint.

 

[Golfman25]

Marine Tex sounds like it would work.

 

[yobub]

How wide of an area do you need?

Thanks guys.

The gap is only about 3/8th of an inch wide, maybe 7 inches long. The part I need to finish runs from about 80 degrees to about 200 degrees if you think about the speaker hole as a compass. I thickened the epoxy, but not as thick as peanut butter. I've never used marine tex but they have it at my local west marine. I'm really looking for a finish coat more than a fill coat.

 

[Lazy Daze]

Either of these can be smoothed enough to allow paint to work as I mentioned above. At 3/8" thick, though, I'd probably strengthen the gap with some glass, first. If you don't want to use paint, you can use gelcoat on top of either. Spectrum is the company you want to get the gel from. It will require slight overfilling (after leaving the fill slightly low) and then sanding. Gel should be applied thin - too thick and it will crack. You'll need to pre-sand into the surrounding material to make this imperceptible.