to sand or not to sand

GlenDC · #1 (**permalink**) 06-13-2007

How do I know whether I should sand/strip hull before bottom paint job or not? I am considering buying a used boat and the owner stated clearly that it need bottom paint. He does not know if she's been ever sanded and when last time the bottom was done. Also, when a marina does bottom paint is sanding included?

KenD · #2 (**permalink**) 06-13-2007

No,just like anything else if you don't ask they will not sand or for that matter do anything.

SailorMitch · #3 (**permalink**) 06-13-2007

You need to look at the bottom paint first before deciding what to do. If it has a million coats that are peeling and flaking, and the surface in general looks like the surface of the moon -- then you need to think about stripping it down to bare fiberglass. Or if the paint is in fairly good shape, a light sanding will do to provide some "tooth" for the new paint to adhere to. In short, yes you probably will be sanding at a minimum.

Are we to assume you will have this boat surveyed? Unless the boat is very small and very cheap, your answer to that question ought to be yes. Make sure the surveyor knows you are concerned about the bottom. He/she should be looking for blisters anyway.

sailingfool · #4 (**permalink**) 06-13-2007

Quote:

Originally Posted by GlenDC

How do I know whether I should sand/strip hull before bottom paint job or not? I am considering buying a used boat and the owner stated clearly that it need bottom paint. He does not know if she's been ever sanded and when last time the bottom was done. Also, when a marina does bottom paint is sanding included?

Assuming you want a smooth, fast bottom...
If you have areas of bottom paint flaking off, then you should strip the bottom, otherwise just follow the instructions of the paint relative to preparing the bottom before painting. Use an ablative paint...see http://www.yachtpaint.com/USA/hotlinks/compat.pdf for compatibility - see if the PO can tell you what paint was used previously. Note that stripping a boat bottom is just about the natiest job in boating and not a task to tak on lightly - it might cost something like $30 or more a foot to have a yard do it...

If you don't care about a rough bottom, ignore any flaking.

GlenDC · #5 (**permalink**) 06-13-2007

Surveying fee will be greater than boat's price. The boat is good but interior is a total mess so the guy sells her for really cheap. I am still climbing to that level where surveying is a must.

sailingdog · #6 (**permalink**) 06-13-2007

Proper preparation of the surface is the best way to ensure the paint will stick properly. You don't always have to sand. Some paints, like ablatives, can be put on directly over a previous layer of the same paint with very little prep work.

sailaway21 · #7 (**permalink**) 06-13-2007

Do not ignore compatability issues with bottom paints. Bottom paint is not cheap. If you do the job right, initially, you are then looking at just an annual coat ot keep it in good condition. It would be an expensive waste of time to just paint it without having determined what was on it previously, and having your paint fall off. I stripped mine this year for just that reason. I recommend a pressure washer. It got about 75% of the paint off, especially the heavy stuff, and after that the rest was more an exercise in tedium rather than hard work.

sailingfool · #8 (**permalink**) 06-13-2007

Quote:

Originally Posted by sailaway21

Do not ignore compatability issues with bottom paints. Bottom paint is not cheap. If you do the job right, initially, you are then looking at just an annual coat ot keep it in good condition. It would be an expensive waste of time to just paint it without having determined what was on it previously, and having your paint fall off. I stripped mine this year for just that reason. I recommend a pressure washer. It got about 75% of the paint off, especially the heavy stuff, and after that the rest was more an exercise in tedium rather than hard work.

Pressure washer - that's interesting, where did the toxic residue go? Is there some wrinkle so you don't risk landing in front of the EPA?

Yards around here only permit the use of vacuum sanders, and if they see any paint on the ground - big $$$ for their mandatory cleanup...

Freesail99 · #9 (**permalink**) 06-13-2007

I could never use a pressure washer where I am. But I have to say after removing 17 layers, yes 17 layers of paint, my yard has been great about the "colorful" ground surrounding my boat.

GlenDC · #10 (**permalink**) 06-13-2007

The marina I consider to take the boat to offers power wash $2/foot, bottom paint and "prep" before bottom paint $10/foot (do not know what they exactly mean under "prep"). The owner provides paint. They also allow only vacuum sanders and I am not sure if rent sanders to boaters.

I'd guess a serious boat owner should buy a vacuum sander.