Bottom Painting Options

[MaineGuy]

Still new to some of this stuff, so please bare with me.

1973 Pearson P39, boat is on the hard, trying to get her ready for the water.

The current bottom paint (I believe) is an ablative paint. It wipes off with the brush of my hand (or on my shirts ). It is chipping, peeling, stained and generally just looks bad.

Advice I was given by my boat yard was to scrape the loose paint off the hull, fair it out with an orbital sander so the entire hull is smooth and go over it with another layer of paint. All of these seems reasonable to me, however I'd like to know if I can go over the hull with a hard epoxy paint, rather than just slathering on another layer of ablative paint?

Looking at Pettit Copper Bronze as the epoxy paint. If we have to use an ablative paint, then we'll probably lean toward Pettit Trinidad.

[Suijin]

Trinidad is hard paint.

The yard is giving you good advice. Invest the time now to fix it and it will be much easier to maintain.

With a heavy buildup however you may find the orbital, even with 40 grit, won’t work well. Sometimes it just ends up burnishing the paint given it’s metal content. A potentially better option is a grinder/polisher with an 8” soft pad and 40 grit. Much faster although requires some finesse. THEN finish it off with the orbital.

As for your paint choice, different paint works better in different waters. Your best strategy is to ask what everyone in your local waters uses. Ablative is great if you sail a lot, not so great if you sit at the dock.

And I doubt any paint, other than more ablative of the same brand, will adhere well to ablative. If you’re taking the surface down to the gelcoat then you should barrier coat before putting antifouling on. And given you have no idea what paint is on there now other than it being ablative, I would take it all off.

[fstbttms]

[gamayun]

You definitely should sand it down to "good" paint but you might also find you can't ever get to a good layer. I ended up sanding all (some 30 years?) paint off my boat, put on new barrier coat, and repainted with a hard paint because I clean the bottom often for racing. The reason I did all that was because as I was sanding, it would just continue to chip away. I also didn't know what kind of paint was on the bottom so getting something to adhere to it could have been tricky. Old paint upon layers of old paint is heavy. Also, it seemed that one of the layers might have been painted over algae because it looked brown. That said, I had gotten more than 2 years out of the ablative paint that was slapped on when I bought the boat. This included cleaning the bottom with soft rag about every 6 weeks and seeing the ablative washing away. Taking all the paint off was a lot of dirty work but I'm glad I did it. Now I can say I truly "own" the results moving forward.

[MaineGuy]

Originally Posted by fstbttms

This looks like a decent graphic that could explain some things for me, however when I click this link, it says the photo has been deleted.

[MaineGuy]

Originally Posted by Suijin

Trinidad is hard paint.

The yard is giving you good advice. Invest the time now to fix it and it will be much easier to maintain.

With a heavy buildup however you may find the orbital, even with 40 grit, won’t work well. Sometimes it just ends up burnishing the paint given it’s metal content. A potentially better option is a grinder/polisher with an 8” soft pad and 40 grit. Much faster although requires some finesse. THEN finish it off with the orbital.

As for your paint choice, different paint works better in different waters. Your best strategy is to ask what everyone in your local waters uses. Ablative is great if you sail a lot, not so great if you sit at the dock.

And I doubt any paint, other than more ablative of the same brand, will adhere well to ablative. If you’re taking the surface down to the gelcoat then you should barrier coat before putting antifouling on. And given you have no idea what paint is on there now other than it being ablative, I would take it all off.

I should have been more specific about how many layers "appear" to be on the bottom. Also, the boat is in Maine, heading to warmer waters before the beginning of the year (Florida, Bahamas, etc).

Right now, as far as I can tell, there is a barrier coat that is dark blue colored. Then a layer (possibly two) of the baby blue ablative paint. I say possibly two layers because the ablative paint is thick, but scrapes off as one layer.

I could get all of the ablative paint off with some elbow grease and paint scraper. The barrier coat is solid - no chips, no flakes, not coming off without some SERIOUS work.

I guess if I am down to the barrier coat.....or mostly to the barrier coat and the bottom is fared well, then I would be open to suggestions for bottom paint.

[fstbttms]

Originally Posted by MaineGuy

This looks like a decent graphic that could explain some things for me, however when I click this link, it says the photo has been deleted.

Try this:

[MaineGuy]

Originally Posted by fstbttms

Try this:

Much better - and if I am reading the graph correctly I have old AF paint, going to apply Trinidad Pro or Trinidad SR, so I just need to sand and apply. Correct?

[fstbttms]

Originally Posted by MaineGuy

Much better - and if I am reading the graph correctly I have old AF paint, going to apply Trinidad Pro or Trinidad SR, so I just need to sand and apply. Correct?

Well, if you have an ablative on there now, you'll need to "heavy sand & apply."

[MaineGuy]

Originally Posted by fstbttms

Well, if you have an ablative on there now, you'll need to "heavy sand & apply."

Perfect! I think that is the plan for me then. Will let you know how I make out, although I suspect I won't REALLY know until I've sailed her and then inspect the bottom down south.

Thanks all for the input!