Cleaning bottom paint

[Regal2800]

I have a 52c and like many others here i have years and years of bottom paint accumulation. I would love to bead blast the bottom, but the problem is a have many small blisters. (quarter size) Bead blasting will obviously open them up and ill be forced to peal the bottom and re fiberglass it. Is there any other way to remove the paint so i can get a nice bottom without abrasives? Paint remover maybe? The diver is also complaining that my paint has lost all of it's anti growth chemicals and that white coral is growing everywhere within a week.

Ive noticed this over the last few trips that ive lost about 1knt and a dirty bottom makes the most sense. Engines do not smoke and achieve their 2300 loaded RPM at WOT. Any input would be appreciated.

 

[dsharp]

Whether the blasting procedure opens the blisters or not depends on the media used, the pressure you blast at, and the distance that you hold the nozzle from the hull. You can cut all the way through the hull if you try hard enough. You can also use a water injection nozzle which will soften the impact and keep the dust down. You can blast it with soda or a fine plastic media and it shouldn't remove any of the gel coat unless it's really loose. I can't think of any good reason to peel the whole bottom. Blast or grind the blisters open, let it dry out and fill with something comparable to VC water tight. Then apply a barrier coat and bottom paint. Search 'wet blasting' and media blasting and you will see what's available. Most good blasters will try different things to get the results you want.

 

[Regal2800]

is it necessary to leave the boat out of the water for a few months to let all the blisters dry out?

I will talk to my yard tomorrow and see what they say. Sounds like a good option. Every time i haul out i usually grind out and fill a few blisters anyway.

 

[dsharp]

It would be best if you can leave it out for a while. I don't know that a couple of months is necessary. Blisters are one of those things that owners have different opinions about. A few small tight blisters aren't that big of a deal. The bigger ones may go into a couple of layers of laminate and should be ground out. If all you want removed is the bottom paint, a 60 grit sanding disc on a foam pad will remove it pretty quickly. It's pretty nasty work though. The worst thing is that the new, least experienced hands start on bottom jobs. They can do a lot of damage with a grinder.

 

[Texastailboard]

We had used a dustless blasting system like some call it hydro blasting. There was at least 12 plus probably more like 16 coats of paint on the bottom. It took all of that off in about 1/4 of the time and really not messy. It uses pressurized water with crushed glass as media. Really happy with the results, I was told by one individual that I was getting a quote from the soda blasting leave microscopic soda left in the surface that is blasted. Some automotive coating are not recommended to be placed over soda blasting.

 

[jim rosenthal]

Soda is water soluble, so you should be fine with soda blasting if you wash the hull with water. Soda is the least cutting of all the blasting media, I think; it did fine with my boat.

 

[spartonboat1]

Soda is water soluble, so you should be fine with soda blasting if you wash the hull with water. Soda is the least cutting of all the blasting media, I think; it did fine with my boat.

There are rigs (I have one), which feed soda (std. bicarb of soda, in 50# bags), into the flow with any pressure washer. Mine is 3,200 psi. A special tip is fitted to the pressure washer outlet and a hose that draws in the soda.

When I used mine, it would removed loose paint right away and older bottom paint would come off with more time, let's say 6" x 2" in 10secs , leaving the grey barrier coat in place. If you bear down, eventually the barrier coat can be worn off, but takes effort (long blast time).

These type of washers/soda blasters are often used to remove grafitti from bldgs and paint from concrete.

 

[Luckyducky]

Where do you buy the 50# bags of soda, is it mixed into a solution for the pressure washer.

 

[Regal2800]

some great info guys. I thought the only way to strip the bottom paint would involve mega bucks. Most pressure washers i have seen simply require a hose hook up. where do you buy the soda material and how do you incorporate it into the pressure washer?

 

[spartonboat1]

Pix of Soda Blaster:
Yellow Barrel:

Blaster Tip with my quick disconnect installed and black plastic shut off handle:

Barrel with length of hose attached and black drain cover:

 

[spartonboat1]

Pix Set 2:
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View of bottom of tank out of which the Soda is drawn and the vertical foam air filter. The plastic opaque hose is fairly stiff and slightly unwieldy but manageable.


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End view of blaster tip, show the broadened shape, which sends out a 1" or so wide by 1/8-14" thin flow.


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Good view of blaster tip, plus disconnect through which pressurized water flows, and Soda flow shut off valve. The Venturi action draws the Soda powder into the water flow and both exit thru the shaped tip:

 

[spartonboat1]

Picture of entire rig: Barrel in frame on wheels, attached soda hose, bottom outflow, and the mixture spigot/tip. Is actually hanging vertically on my garage wall, not sideways.

 

[spartonboat1]

Where do you buy the 50# bags of soda, is it mixed into a solution for the pressure washer.

I use for Soda Blasting

Armex baking soda.
1-800-332-5424


Have always been in 50# bags, which is the capacity of the barrel shown in pix above.
Ask them for an outlet in your area.