Small Fiberglass Repairs and Gel Coating

[Derrick Fronckowiak]

I'm brand new to fiber glass repair, finishing and gelcoating, so please excuse my ignorance and stupid questions. I got a few old screw holes and some nicks and dings to patch on my 1990 Bayliner Capri. Some of the dings are on the bottom of the hull and the old screw holes and other dings are on top around the cockpit. I think I can handle filling the holes with resin (add some fine fiberglass to bind) and sanding it smooth to the surrounding area (knock on wood). My questions: Is gel coat the final application of coating finish to be applied and does it also serve as both the coloring and the "gloss" for the finish? Is it sanded afterwards? Buffed out? Also, can/should gel coat be sprayed or should it be brushed on?

 

[tpenfield]

If you apply a piece of clear plastic to the gelcoat then it will take on a smooth appearance consistent with the surrounding area, and require little/no sanding. The clear plastic material often comes with gelcoat repair kits.

If you do need to sand, you will want to use the finer grit papers (1000 - 2000 grit) and wet sand lightly to finish it off to a decent shine. You may want to buff it as well, depending on how good a match you have.

For spot repairs, it is best to dab it on the area and cover it with the plastic sheet material. You can even 'roll' the plastic sheeting to get a finished shape to curved areas, such as the keel or the edges of strakes.

 

[Scott Danforth]

When I did the dock rash on my searay, I used the spectrum gel to match, then when dry, I wet sanded, starting with 320 grit to knock off the high spots, 600 grit to bring the new gel down to surrounding height, then 600, then 1000 grit. from there I fired up the buffer.

for a few other areas, I have used shipping tape to hold near shape.

just be advised, with a near 30 year old boat, your not going to match the color

 

[Derrick Fronckowiak]

tpenfield and Scott, thank you both for your sage advice. I'm learning as I go, so this will involve lots of questions (that have never occurred to me before). And I really get what you are saying (Scott) regarding matching the old paint shade, just can't simulate the aging/fading surrounding area. Interestingly, auto body places use computer scanning and technology to create matching paint that compensates for aging and fading, so that you can at least come a lot closer to blending the new paint with the old existing/surrounding paint. Maybe someday....

 

[ondarvr]

If these are just small screw holes don't do any glass work, keep the repair as small as possible, most of the time you can just fill the hole with gel coat and put the plastic over it, when it's hard you peel it off, if done correctly sometimes you don't need to touch it after that.

​Put some car wax around the hole and buff it off like normal, this will keep excess gel coat from sticking around the hole.
Use a countersink bit to slightly clean up the edges of the hole.
​Now fill the hole with gel coat, sometimes you may need to plug the bottom or backside of the hole, tape works well.
​Lay the plastic over the gel coat and smooth it out completely.
​When it's hard peel off the plastic, you should be able to easily scrape off any excess gel coat from the waxed surface around the hole.

​If done correctly you will have a small perfect circle of a slightly different color, it will be slightly sunk in from the gel coat shrinking, but it won't be that noticeable.

Going further frequently opens you up for more color match issues that may be far more noticeable.

 

[Derrick Fronckowiak]

ondarvr,that's great advice. These screw holes (there are four of them in a square pattern) were used to mount an antenna bracket. They are each about 3/16" in diameter. Same goes for most of the little nicks and dings here and there in the finish. Do you think I can fill that with just gel coat?

 

[ondarvr]

it should work, don't do it in the sun.