Bottom painting & sanding

[Brian Hickson]

Hello. Just purchased my first boat,a CD25D in excellent condition. The bottom is in very good condition with just a few spots having the paint flaking off. Do I need to use an electric sander to sand the entire bottom, or can I manually scrape the flaking areas as well as manually sanding [roughing up] the bottom prior to painting? As you can surmise, this is a commisioning 101 question. Thanks.

[Mike Everett]

In this case, less is better.
You can paint over last year's bottom coat with minimal preparation, just a manual once over the rougher spots.
Personally, I would avoid using an electric sander on the bottom because scraping through to the fiberglass invites water absorption.



everett@megalink.net

[Duncan Maio]

Do I need to use an electric sander to sand the entire bottom, or can I manually scrape the flaking areas as well as manually sanding [roughing up] the bottom prior to painting?

FWIW, here's what I do:

Powerwash the bottom, or wash it with lots of water and a stiff brush. This should take most of the flaking paint off, and usually reveals some more areas that I didn't think were loose.

I sand only the areas where there has been flaking or peeling paint; I know others who sand the entire bottom. I have noticed that the peeling is generally from the lowest layers (i.e., not the stuff that I applied). In any event, I do not sand the entire surface.

I apply two coats at the waterline and leading edge of the keel and rudder; everything else gets one coat and seems to do fine. I can do a CD27 with one gallon.

Paint compatibility is an issue; it helps to know what is on the boat now. If it is a "hard" paint, you can put almost anything over it; ablative paints must be followed by other "soft" paints, and vinyl and teflon paints are their own animals. Odds are, your boat has either a modified epoxy or an ablative paint; check out the West Marine catalog for descriptions and selections.

I prefer the "single-season" ablative paints, because there is minimal preparation, and I know that I would not carefully inspect the hull each season if I didn't paint it.

Good luck.

Duncan Maio
s/v Remedy
CD27 #37



dmaio@att.net

[Lee H. Hodsdon]

Brian,

As Duncan said, there are many approaches. So to paraphrase, here is my two cents worth. When I purchased LOKI, our 25D I merely wanted to get the boat in the water and out of the grips of the boat yard! The survey showed no moisture in the hull, with some spots of flaking in the existing bottom paint. I did nothing and had her launched. At the end of the season there was some growth, but not real bad. That winter I scraped all of the old bottom paint down to what appeared to be old barrier coat. I then smoothed the surface with an electric sander, filled any dings with thickened epoxy, and applied Interlux 2000+ barrier coat per the manufacturers instructions. This was followed by an ablative paint mentioned in Mike's response, Interlux CSI was the brand. The first of three layers was a contrasting color to the final two coats. Since that time (4 seasons) I've only had to touch up the bottom paint at the areas which the first coat color shows. No sanding, no buildup and a clean hull.

I don't know how to display photos on this bulletin board, but if you are interested, I can e-mail before and after photos of the barrier coat process.

You are going to love the boat!

Sihcerely,

Lee



lhodsdon@nh.ultranet.com

[Brian Hickson]

Everyone, Thanks for your help. I'm sure I've saved time and expense by asking a "stupid question".