Bottom painting

[David Arnold]

I will be painting my boat this spring for the first time since it was newly launched in 2005.  The dealer applied an ablative paint which is showing a few signs of wear after 2 seasons and one winter in the water.  The bottom was power washed after hauling last fall and is quite clean at this point.  What prep steps should I take before applying a couple more coats of ablative paint which hopefully will last me 2 more years before another haulout?

[sdaly66]

David,

If you're gonna be in the water for two years before your next haul, I've just got one word for you - OVERKILL!

If it were me, I'd do a number of things.

1. Check the barrier coat if it has one.  If it doesn't - put one on. This involves taking off everything that is on there now.
2. On top of the barrier coat, I'd put three coats of ablative - given that you plan to be in for two years.
3. The bottom ablative coat should be of a different color than the other two, that way you'll be able to visually tell when you need to apply more.

If you are comfortable with the barrier coat and just want to cover with ablative, here's what I would do.

1. Give her a good sanding by hand with a block and medium-fine grit paper.  Sand everywhere that there is bottom paint.
2. Acetone bath, should take a little less than a gallon.  Do this by hand and have at least three sponges at the ready for the job.  Rinse them often to keep them clean.  Wear latex gloves (or the like) and put an insulated work glove on over the latex - this stuff evaporates and is quite cold on the hands.  What you're doing here is getting the hull really clean.
3. Three coats of a good ablative paint with the bottom coat of a different color as indicated above.

Hope this helps.  Like I said, two years in the water, I'd go overkill.

[Larry Robertie]

David,

1. Check the barrier coat if it has one.  If it doesn't - put one on. This involves taking off everything that is on there now.

On my boat the barrier is applied under the bottom gel coat.  The PO was concerned about having a barrier coat and wrote Catalina an email asking abouyt it.  I have a copy of Catalina's responce, the barrier coat is built in.

[Steve Sayian]

Dave,

I had the bottom soda blasted this January and am going to put on 3 coats of Interlux 2000 barrier coat. The boat has a sporadic barrier coat on it (the stands weren't moved and behind the pads were bare white and the barrier coat is grey) but I want to add more since it had a few blisters on the Starboard bow area.  After the barrier coat (when the 3rd coat is tacky), I'm applying a coat of inexpensive modified hard epoxy paint and then 2 coats of Micron Extra ablative.

Before I bought the boat in 2006, it had been kept in the water for a couple years at the Melville Marina in Portsmouth, RI.  I think that may be the reason for the blisters and the bad barrier coat.

I agree with Sdaly66, do it right the first time and you should be all set.

Steve

[Roc]

David,
I think your question is how to prepare the current paint in order to apply more coats of ablative paint.  You say the current paint is still in good condition and well adhered to the hull.  If so, what you can do is wet sand the current coat using a coarse scotch pad. Wet sanding holds off any dust.  Sanding dry just makes a mess of things, and subjects you to the toxic dust.  Wear a tyvek suit (home depot) to protect your skin and so you don't get soaked.  Then just apply the new coats of paint. 

[Bob K]

David,
Here's an answer you might like....don't sand!   That's one of the beauties of ablative paint.   I stopped sanding ablative paint years ago except in spot areas which need work or cleaning.  I make sure the bottom is power-washed well at winter haul-out, and then in the spring I only sand (lightly) around the waterline where the power-wash couldn't get all the scum off.   I've used Fiberglass Bottom Coat ACT, and switched several years ago to the WM generic equivalent.  Never had a problem with coats not sticking to each other.  Maybe paint type/brand, location, or water differences matter.- I don't know. You might want to read the paint can directions - I think I recall the ACT can saying sanding was minimal or not necessary.  One more thng - I paint yearly - maybe after 2 years a light sanding is needed all over to remove dirt.