Bottom Paint Removal: what am I getting into?

Toddavid

Petty Officer 2nd Class
Joined
Sep 8, 2012
Messages
172
Looking at a very low hour fiberglass hull boat with Interlux Micron applied 4 years ago.

I don't do any boating that requires bottom paint.

In fact, some places I trailer to prohibit TBT bottom paint (which this is not), which suggests that I could get flagged at an inspection station by a cranky clueless inspector.

Some people say that there is no way to remove without also planning on major gelcoat reconstruction.

Some say it will wipe right off with proper stripper.

This is a pretty new, expensive boat. I'd be paying a pro to do the work.

What should I expect here? What are my risks? What would you do?

Thanks.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,033
To get the A-F paint off w/o damage to the gelcoat is tricky. First you need to know what is under the A-F paint. It could be a primer or a barrier coat, or nothing. I would take some sandpaper and sand it down carefully in an out-of-the-way area. Use progressively finer wet sandpaper until you expose the gelcoat or other layer.

If no primer, maybe soda blasting would fit the bill. If you have a primer or barrier coat, it may be tougher to get that off, as A-F paint is soft.
 

frantically relaxing

Senior Chief Petty Officer
Joined
Nov 19, 2011
Messages
699
Applying bottom paint from the getgo typically requires the gelcoat be aggressively sanded so the Interlux or whatever base coat will adhere properly. If it's a bigger, newer boat, you can bet that's exactly what you'll find.

On smaller boats, bottom paint is typically seen as a liability to its resale value. On larger boats destined for slip use, having the bottom already done would be a bonus to many future buyers.

My advice would be to leave well enough alone. Worst case other than you don't like it, is you'll never have to worry about blisters. ;)

Vivid bottom paints come in enough colors that you should be able to closely match the color of the hull. Paint it to match, pick up a 2" roll of vinyl tape and cover the seam between the bottom and top paints, and your bottom paint will be barely noticeable... :)
 

shrew

Lieutenant
Joined
Dec 29, 2006
Messages
1,309
Some people say that there is no way to remove without also planning on major gelcoat reconstruction.

This is accurate. The smooth gelcoat was prepared with 80 - 100 grit sandpaper. If properly done, it was done with a machine such as an orbital sander. You can't hand sand adequately to ensure all the modl release and every square inch is properly sanded.

Some say it will wipe right off with proper stripper.

I say, I doubt these people have actually removed anti-fouling paint before. (I suspect THEY, in turn, heard from some joe bagodonutz that this works). If they did, the bottom of the boat was not properly prepared. If it were that easy we'd see thousands of professionals doing this and not scraping and blasting. I trust what the pros are doing.

If you remove the paint, you will not be happy with the results. Even if you decide to repaint the bottom (roll and tip) with white awlgrip type of marine topside paint, that will be pricey and time consuming.
 
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