Bottom Paint- Priming Fiberglass?

[Chinacat]

As a former painting contractor, i tend to get a bit obsessive when it comes to the bottom paint. I've been using an ablative type for 10+ years. Every fall when it comes out of the water I power wash it, gentle as possible but strong enough to remove what needs to come off, and in the spring I lightly sand the bad areas and prep for a fresh coat. Last falls power washing knocked off lots of paint and after my light sanding and prep I've many spots- some bigger than I'd prefer, down to the gel coat. The painter in me wants to prime those spots before putting fresh coat of paint on. I've researched as much as I can and there is surprisingly little info out there. Lots of info on what to do on a new hull for the first time but not much on "spot priming" these bad areas.

Based on what i did find, I picked up a quart of Primocon by Interlux and planning on hitting these spots while we have dry weather today and tomorrow.
It's main purpose appears to be for metal below the waterline but the specs also say suitable as a primer on fiberglass.

Anybody have an experience or advice for this type of situation and/or product?

 

[Leprechaun]

Yes, I do. When I bought my boat, back in the Pleistocene Era, I stripped the old bottom paint myself, using a automotive windshield sticker razor scraper and tons of time laying on my back. Yucchy job, but it came out nice, right down to the bare hull. I then ran my trusty Makita palm sander over the entire hull, with 80-grit paper to get some "tooth," and primed with a coat of Pettit Bottom Prep - no sand type. This goes on in a sort of dull metallic color, kinda like "liquid zinc."

After that two coats of Interlux ACT in blue - and good to go. Every season I give it a skin coating of fresh ACT - and here we are 23 seasons later, still looking good.

Pro tip - If I recall correctly, you have to put the bottom paint on while the primer is still slightly tacky. Not an issue as the primer dries fairly quickly. I rolled on the primer and by the time I finished at the stern, the primer at the bow was ready for the bottom paint.

Came out really nice. To this day. Lep

 

[Chinacat]

Thanks Lep
I went ahead and used the Primocon. It's a lovely shade of light gray... I double checked all the specs and it clearly said 8 hrs minimum dry time before applying topcoat so it must a little different than it was 23 years ago

As noted before, the painting contractor in me came out and what started out as a spot priming project turned into priming more than 50% of the hull.

Looks nice and even and smooth for the topcoats that i'm hoping to work on tomorrow.

 

[Chinacat]

Project completed! Very happy with the final results and the way the the topcoat of bottom paint when on over the Primocon! Now on to prepping everything topside to get ready to launch. Weather the next few days not looking very cooperative.

 

[Chinacat]

So after all the time I spent prepping, priming, painting over the past week and feeling good about myself, the dumb ass that lives across the street from me has some dude come to his house this morning and "paint" the bottom of his boat in all of an hour.... Go Figure

 

[BennyV]

So after all the time I spent prepping, priming, painting over the past week and feeling good about myself, the dumb ass that lives across the street from me has some dude come to his house this morning and "paint" the bottom of his boat in all of an hour.... Go Figure

LOLOL. I usually do a few bottom painting jobs every year. I usually put an ad on Craigslist. Didn’t get around to doing it this year.