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  Pressure washer to remove bottom paint?

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Author Topic:   Pressure washer to remove bottom paint?
Plotman posted 10-09-2003 09:05 PM ET (US)   Profile for Plotman   Send Email to Plotman  
The bottom paint on my boat is in rough shape - at least 3 coats and very patchy.

Is there any reason at all not to get as much paint off mechnically with a power washer as I can before I go after it with a chemical stripper? Working on the transom with the spray tighenteded down to a narrow stream, I'd guess I'm taking 70% of the existing paint off with my 1600psi sprayer.

Drisney posted 10-09-2003 11:47 PM ET (US)     Profile for Drisney  Send Email to Drisney     
Do a site search for removing bottom paints...many experiences will come to light, as for the pressure washer; if I am not mistaken, someone tried that and damaged their gel coat.....Dave
jimh posted 10-10-2003 08:31 AM ET (US)     Profile for jimh  Send Email to jimh     
One correspondent in this forum reported using a pressure washer to clean the hull of his Boston Whaler. Unfortunately, he also reported that the next day a number of blisters appeared in the gel coat.

This occurred after hauling the boat for the season, and it is possible that the appearance of the blisters may not have been caused by the pressure washing alone, but perhaps might have been due to some water coming out of the hull after several months of immersion.

If you decide to go further with using a pressure washer to remove bottom paint, I think everyone would be interested to hear of your results.

BillB posted 10-10-2003 09:05 AM ET (US)     Profile for BillB  Send Email to BillB     
Having pressure washed far too many acres of boat bottoms including quite a few Whalers I can assure you that the force required (tight cone of spray)to remove the paint from a properlyprepped hull could indeed cause damage. The pressure finds and exploits any imperfections, especially damage from osmotic blistering. I'd be a little concerned using the full 1600# of pressure available.

It's a piece of cake on a hull with no or bad prep. Try it, you'll know right away if it's going to work, just be careful. I was lucky with my Montauk and got 95% of the paint off using a minimal amount of pressure. The hull under the paint showed no evidence of sanding or other prep at all.

Otherwise break out the scraper or try one of the chemical approaches discussed on this forum.

SpeedBump posted 10-10-2003 10:17 AM ET (US)     Profile for SpeedBump  Send Email to SpeedBump     
I have used pressure washers to remove bottom paint with good success on both of my Whalers and several other boats. As with all processes around gelcoats you do need to use caution, gelcoat can be damaged with high pressure just as it can be gouged with a scraper or blistered with the wrong kind of paint remover. I think that with proper care a pressure washer is safer than scraping.

While I have never measured the pressure of the wake stream off the transom and botom of the hull, I find it is similar in form as a good pressure washer spray. I also have observed that the bottom of the hull in this area is always cleaner that the rest of the hull except where the chine and bow at water line enters the water at the leading edge.

My methods include pressure washing immediately upon hauling before the water can flash off of the bottom paint or the scum dries up. Pressure washing a boat bottom that has been sitting high and dry for a while can take twice as long to clean. I use the spray at an broad angle to the hull rather then a direct 90 degree approach. I do not try to get every last bit of paint off. I am mostly concerned with scum, loose paint and built up paint. Depending on the pressure of the spray never put the jet stream of the nozzle directly against the gelcoat, work at a distance (6"-12") and move into/towards the paint until you begin to get results you are looking for and keep the wand moving so you don't have continuous pressure on one point of the hull.

Most bottom paints are ablative, a pressure washer properly used simply wears away the paint coating much more quickly under high pressure. I usually stop when there is a very thin or opaque coating of paint left.

A light hand sanding in the spring or when prepping for repainting will take care of the rest and give a well prepped bottom.

If you have an older hull whose gelcoat has seen better days and has small patches of gelcoat repair, marine tex or even bondo you can blast these repairs out if too much pressure is used. But if they are that loose in the repaired section they are most likely improperly done repairs or leaking to begin with and should be attended to anyway.

raygun posted 10-10-2003 11:15 AM ET (US)     Profile for raygun  Send Email to raygun     
Well said speedbump. I am just getting ready to haul my Montauk out for the winter and follow the procedure you explained. I think it saves tons of time in the spring, especially with my ablative Micron CSC bottom paint. This season I didn't even repaint as CSC is multi-season. I use the 15 degree nozzle on the hull, never getting closer than 4 inches. Takes the slime and dead paint right off. Only on the tilt unit and transducer thingy do I use the zero degree to get rid of the barnacles that always wind up there. I think I'll try some of that clear antifouling on the tilt next season.

Since I spent many hours sanding and prepping the hull 3 seasons ago, I no longer even sand before painting in the spring, I just blast it again, let it dry, tape and paint. My opinion is that the results are excellent.

Plotman, I believe you should try the pressure washer first using speedbump's advice, but with more pressure (I use about 2600 psi) and the 15 degree nozzle. Then finish with either the chem stripper or sanding as need be. Most importantly, are you going to repaint or do you want a bare hull?
Ray

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