Bumps in Gelcoat - blistering?

[Iroc-Sea]

Hey all,

I have an 18’ bowrider, 1983 Cobia Sportster, have had it for the past 13 years. The past 3 seasons I’ve had it wet docked for the summer months in Lake Hopatcong NJ. I pulled it a few weeks ago but today when I washed/ waxed it, I noticed some bumps in the gel coat below the water line. It looks like it’s on only one side of the hull.

Not sure if this is blistering or something else? Is it serious or can I get a few more seasons out of it without sanding/repairing gelcoat? The first picture shows the bumps, on port side only. The second picture is starboard after waxing - free of bumps.

Thanks!

 

[Scott Danforth]

blistering

 

[Iroc-Sea]

blistering

Yeah that’s what I was afraid of. Should I be immediately concerned or is it something I can let be? It gets wet docked in fresh water 5 months a year.

 

[zool]

Personally, I would just monitor them to see if they keep appearing across the hull. Its a progressive problem so it usually gets worse over time. Fixing a few at a time is like whack a mole.

The proper fix would be to get the hull scraped, filled, and gel coated.

You really should have a barrier coat and anti fouling or epoxy coat if wet slipped for the season, even on Hopatcong (fresh water)

 

[Iroc-Sea]

Personally, I would just monitor them to see if they keep appearing across the hull. Its a progressive problem so it usually gets worse over time. Fixing a few at a time is like whack a mole.

The proper fix would be to get the hull scraped, filled, and gel coated.

You really should have a barrier coat and anti fouling or epoxy coat if wet slipped for the season, even on Hopatcong (fresh water)

Thanks for the info! Appreciate it. Will definitely monitor it going forward. Also great tip with the coating - I assumed freshwater didn’t require any type of coating (dumb!).

Yeah I’ve been doing some research - lot more to go. From what I read so far, it seems like anti fouling (bottom paint) won’t really offer any protection from osmosis, it’s more to prevent marine growth.

Should I just go with an epoxy barrier coat or will I have to put anti fouling on top of that?

Think I could paint right over existing damage?

Looks like West Marine and Interprotect 2000e are popular brands. Any recommendations?

 

[Scott Danforth]

typically if you are mooring

2-3 coats of barrier coat followed by 2-3 coats of bottom paint

the barrier coat protects the gel/fiberglass from blistering
the bottom paint protects the barrier coat

 

[Iroc-Sea]

Got it, that makes sense. Think it’s okay to paint over as is?

 

[Scott Danforth]

Got it, that makes sense. Think it’s okay to paint over as is?

I personally would take care of the blistering, re-gel, then barrier and bottom paint

However it is your boat. its up to you.

Since the boat is well past its design life, I would also entertain just using it as is and tossing the boat in a few years.

 

[Iroc-Sea]

That was the initial plan hah

Looking to get maybe 2-3 more seasons out of it tops, that being the case so you think epoxy / bottom paint will get me there? Or roll dice and do nothing? Definitely don’t want a big bill repairing wouldn’t be worth it

 

[flashback]

If it were me I would do nothing. I have a 78 sailboat that's covered with them and it's still sailing..

 

[Chris1956]

Let it go until the spring. They may dry out. I get those in the cockpit, when it is covered by a wet cushion. They dry out after a while

I would still recommend the barrier coating. I did 3 coats of pettit epoxy barrier coat. You mix it(50:50) roll it on and recoat after the time denoted by ambient temp. I did the 3 coats, one per day before work, as the ambient temp specified 24 hours cure time

If she has been good w/o the antifouling, why add it now?

The barrier coats can be dull in color. You might see if one is made to look good. You could also use a marine 2 part polyurethane paint. You would need one for under the waterline usage. The 2 part paint over the epoxy barrier coat would leave no doubt about the protection.