Bottom paint prep - quick n dirty?

[soopad00pa]

My old 30 catalina is out and partially sanded and I'm trying to nail down details for next steps.

In an effort to be relatively cheap and quick, I'm not going down to the gelcoat. The bottom currently has, by concensus, old ablative paint over some kinda barrier coat. It's peppered with epoxy (?) repairs of blisters and has some small pits/blisters that are new. I'll attach pix. Hopefully.

My plan is to smoosh epoxy into any significant chips, gouges, and blisters and then paint a couple/three coats of ablative cootie-cide on top and get back in the water.

I have some west systems epoxy and thickener I'd like to use, but I don't know if I need to prime over that before bottom paint. And if I do, can I just spot prime or do I need to prime the whole thing?

If west sys isn't appropriate, what would work, ideally without priming atop it? Someone in the yard said 'use 2000.' Best guess is they're referring to interlux 2000e barrier system...

Can that be thickened to fill these pits? Just dab a couple coats until thick enough?

Thanks - I rly do appreciate the resource the place is.

[tkeithlu]

I'm only going to go as far as prep, not paint.

First, I'm seeing dark brown stuff in holes, particularly in photo #3. What is that? Barnacles? Whatever it is, it needs to go. That may in turn mean more filling. At the shallow level you're talking about, the patches are not going to be structural, so epoxy filler will do fine.

Second, the prep needs to be "Rough and Clean." You'll get better adhesion with an overall rough surface, say with 80 grit. Then wipe with a solvent.

Then follow the manufacturer's instructions TO THE LETTER with the bottom paint. Bottom paint is tricky stuff, and the instructions vary according to the manufacturer and the individual critter killer. Cut a corner (temperature of the suface when applied?) and it will fail.

[Shrew]

There is a saying when it comes to jobs/projects....

Fast, Good, Cheap. You can only choose TWO.

If you don't take the time to prepare the bottom properly, the job will not take properly. The only way to ensure the new paint bonds properly is by proper and thorough prep.

With paint, you're 80% done by the time you START rolling paint. The actual painting is the last and fastest step.

[Shrew]

I'd do the following:

1) Take the paint down to barrier coat.

-> Consider having the hull media blasted. It is worth the savings of time and money.

2) repair blisters.

3) New barrier coat

4) paint.

[Orion Jim]

You have an active case of osmosis which has never been treated to cure. Just search the web for osmosis treatments and take your pick. You won’t like any of the results. They are all expensive in materials and man hours. All can be done without professional help with varying levels of success based on strict adherence to the method chosen. With boat pox there is no easy way out. Good luck.

[Rod Headlee]

Just paint over them and keep sailing

[aa1bflyboy]

Originally Posted by Rod Headlee

Just paint over them and keep sailing

There is no quick and dirty with Painting boat bottom. If you follow this advice you will only need to do it again in the near future.

[aa1bflyboy]

Originally Posted by Shrew

I'd do the following:

1) Take the paint down to barrier coat.

-> Consider having the hull media blasted. It is worth the savings of time and money.

2) repair blisters.

3) New barrier coat

4) paint.

Shrew is spot on! I am almost done with this same repair on my Aloha 32. I lost a season of sailing but I saved $12,000 by doing it myself. Hopefully I’ll be in the water in April.

[Apollo366]

How long do you think you'll have boat?

If short term, grind out the blisters fill w West epoxy mixed with just enough micro balloons or other filler, see West instructions for making the fill, so it won't run as you apply. Epoxy needs to be primed so paint will stick to it.
I agree with using 80 grit sandpaper, the surface needs to "roughed up" so the bottom paint will adhere.

IF you're going to keep long term & make her better over the years, this article gives the best way of treating blister or "osmosis" of the layup.
https://www.boatsurveyor.net/boat-su...sis-explained/

If you just fill & paint you're kicking the can down the road, and will have to do it sometime.

[soopad00pa]

Boat is now sanded to barrier coat, epoxy from previous repairs, and some gel coat or even bare glass.

There are some new blisters, but not too many and most are pea sized. Only about a half dozen were wet. These I crudely dug out with a screwdriver and tomorrow will clean up a bit with a dremel - the biggest is a bit larger than a quarter.

I'll fill these with epoxy and then spot prime with the interlux 2k ($37/qt here!) over the blister repairs and any gelcoat or fiberglass and bottom metal and then paint, hopefully Friday.

Of note, there's no sign of any catalina smile and I also need to replace my cutlass bearing.

Also gotta do a

[soopad00pa]

Originally Posted by Apollo366

IF you're going to keep long term & make her better over the years, this article gives the best way of treating blister or "osmosis" of the layup.
https://www.boatsurveyor.net/boat-su...sis-explained/

If you just fill & paint you're kicking the can down the road, and will have to do it sometime.

Holy Moly! That must coat a bajillion dollards and take months!

I am most definitely kicking the can!