Below waterline fibreglass repair, paint or gelcoat?

I have deep gouges below the waterline on a fibreglass hulled Riva. I can easily follow You Tube videos for fibreglass repair, however, can I ask:

Is it advisable to paint over a West System epoxy, or should I Gel Coat repair.
Or can I just leave the West System bare?

Many thanks in advance

 

If it has Gelcoat then use gelcoat but first fill the gouges with filler material, you can buy ready made stuff for that.

 

Epoxy has low UV resistance, so you should coat it with something. Either gelcoat or paint will work.

 

Scrapes and gouges are part of the life of a hull in use. The thickness of gelcoat provides better protection to the underlying glass structure than thin paint.

I repair many many gouged hulls. My process is as follows;

Clean wet sand with 1000 and polish to find true color to match to.

Remove any damage and drammel sand gouges

Repair any damaged fiberglass

Brush VE onto any exposed glass. (I don't worry about excess on surface)

Brush and squeegee several coats of unwaxed gelcoat into grooves until full.

PVA or wax paper or tape to suffocate gelcoat.

Sand fair with 80 grit in one direction then 120 in the other.

Chines often need extra attention.

Spray a thick coat of gelcoat.

Suffocate with PVA

Wet sand and polish

 

A repair done with epoxy has higher resistance to moisture than polyester gelcoat does. The coating is only needed for cosmetic purposes.

 

Blueknarr has it the way it'll usually be performed at a yard, though some may elect to use polyester, instead of the preferred vinylester. These repairs are very common and last quite will, assuming reasonable prep and buff out. Getting a good color match will be the butt kicker for the novice, but it'll work/last fine. For deeper repairs other than dings, chips and scratches, I'd use epoxy and fabrics to fill, then overcoat with vinylester.

 

Is this a boat that lives on a trailer or in the water? ( I don't know my powerboats) If there is bottom paint involved there would be no reason to dick around with gelcoat, you would use epoxy filler, primer then bottom paint. If it lives on a trailer then go the gelcoat route.