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  #1  
Old 03-13-2003
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Bottom Job question(s)

All,

I am embarking on my first bottom job over the coming few weeks before launching for the season. I have purchased 2 gallons of bottom paint (ablative) that I am hoping will allow me two good coats on the hull of a 30'' sailboat. The bottom is in good condition and the existing bottom paint has 3 coats (1, base, is black with 2 coats of blue over the black). In only a few spots is the black showing (in and around the rudder) a little bit. I want to prepare the bottom for fresh paint and I don''t want to over look anything, hence this e-mail. I see people in the boat yard scraping and sanding with industrial sanders, chemicals, and all sorts of gadgets. I have 2 gallons of paint, sand paper, and a couple of rollers, tape and some misc painting supplies. I don''t know if I should be laughing at myself or start painting - after I do some sanding. I am trying to determine what is an acceptable amount of preparation for this seasons bottom job (which I plan to do yearly or as required). I am planning to sand the bottom only to the point of providing the fresh paint a surface to bond to. Is this enough or should I take it down further? How much is enough and too much. After sanding I am planning to apply 2 coats of fresh paint over the course of 1-2 weekends as required. Does this sound right or am I missing something. I keep seeing all these people with mountains of equipment and gadgets and I think I am ill-prepared. Please help a Rookie.

Thanks in advance,
Rookie
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Old 03-13-2003
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Bottom Job question(s)

Rook,

You''re on the right path. Main thing is to be sure the old paint is adhering well and not loose in spots. Sand the old paint enough to give it "tooth" for the new paint to adhere to, wipe off the dust with solvent or denatured alcohol and paint away. Two coats will be fine, and easily doable in 1-2 weekends from start to finish. Remember to save some paint and a disposable brush for touching up the spots where the jack stands are when the boat is in the slings.

All the others with sanders and such probably have lots of loose paint to get off, or maybe 10 coats of old, hard paint they want to remove.

Using ablative paint is the way to go, btw. No build-up of coats to become a major pain to remove down the road.

My 2 cents worth.
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Bottom Job question(s)

What a relief. When I saw everyone else with their serious equipment I thought I might be fooling myself for thinking I can get away with doing a bottom job economically. You mentioned a couple of other points I would like to address. You mention ''solvent or denatured alcohol''. What kind of solvent and what purpose does it serve? Is a wash with water inadequate? I was think about having them move the stands because - 1) the boat will only be in the sling for a short period of time - is this sufficient for the paint to dry and 2) I assume they will apply only one coat of paint - would this be sufficient? Thoughts? I sail on the C.Bay and don''t want to risk potential damage in the long run - Blister, etc. I''ve read and heard so many horror stories about bottom peels, blisters, barrier coats, etc, etc. Am I just being too paranoid? If I can leave a used brush and some paint and get the job done, it makes my life much easier. Thank you.

Rookie
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Bottom Job question(s)

First you need to find out what type of bottom paint is on there now and make sure that the ablative paint you have will adhere to it. If the bottom is in good shape as you stated, you want to give it a good sand with some med. grit paper. This is more to give a good adhesion surface vs. "getting rid" of what is on there. Many boatyards require that you either put a tarp under your boat while you sand or use a power sander with a vacuum attachment. Bottom paint is 40%+ copper which is posionous to marine life (obviously) and to humans and other animals. As such, invest in a tevek suit to sand and paint in as well as a 3M (or similar) respirator with replaceable filters. I would also recommend goggles and latex or similar gloves. (No, Im not a paranoid.) NEVER use water to wipe off the hull after sanding; use the solvent recommended by your paint manufacturer. I wud also strongly recommned a low-tack tape like 3M''s Blue line to mask off the hull. This comes off very easily and leaves no residue. Generally I use a roller for most of the bottom and CHEAP brushes for places where you cant get at with a roller. MAKE SURE YOU MIX THE PAINT VERY WELL at the beginning of the process and occasionally while painting as the copper tends to settle at the bottom of the car otherwise. Paint around the jack stands one weekend and then ask the boatyard to move them so you can paint the bare spots the next weekend. Dont move them yourself. Good luck. It gets easier every year.
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Old 03-14-2003
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Bottom Job question(s)

You have gotten some very good advice here but let me fill in some of the gaps....

Ablatives, like all bottom paints, over time eventually loose adhesion on the lower most layers. When this happens, ablatives have fewer layers of paint to remove than other harder forms of paint. Ablatives are prone to paint sickness (as are most other paints) and it shows up as small spider crack, or as peeling paint. Those areas where peeling or spider cracking is occuring should be sanded down to a base layer that ideally is solidly adhered.

The presence or absense of ablative anti-fouling bottom paint has no impact on blistering. Typically the gelcoat and when present the barrier coat, are the water resistant membranes that form the defensive line against osmotic blisters.

It is a good idea with ablatives to sand down through ''last years paint'' so as to prevent a build up. Too much paint is far worse than not enough.

Sanding should be done with increasingly finer grades and the strokes should run the direction of the water flow. I typically use 180 grit to prep for the first coat of bottom paint and 220 for the second coat.

Wearing gloves, I typically wipe down the hull with denatured alcohol, which typically removes any dust and any oils or greases or other contaminants that might compromise adhesion. Frequently change paper towels or clean rags so that you are not simply redistributing the same contaminents.

Masking tape off the waterline and the depthsounder transducer.

Two gallons is a lot of paint to paint the bottom of a typical 30 footer. I typically got 2 1/2 coats out of a gallon on my prior boat, a 28 footer. With ablatives, I would typically ''spot in'' (with an extra coat) the bow, waterline, keel (leading edge and bottom) and rudder as these areas experience more erosion than the rest of the hull.

I would typically roll on the bottom paint with a tight nap roller in a couple square foot area at a time and then ''tip off'' (drag the tip of a brush over the surface of the wet paint) the surface with a foam brush stroking in the direction of the water flow. Tipping off does several things. It levels the high spots in the rolled on paint which greatly helps with light air performance, but more importantly it increases adhesion and removes bubbles from the paint layer. I typically apply several coats of paint in a weekend and feather edge the paint maybe 6 or so inches away from the jackstands and then have the yard move the jackstands applying saranwrap to the top of the jackstand to prevent damage to the new paint and then feather in the paint at the jackstands.

When the paint has dried, I typically wetsand with 400 grit in the direction of water flow to knock down highspots in the paint for performance reasons.

The advise about a high quality dust mask, tyvek suit and goggles is very important. You expect to be around for a while and playing casually with toxic paints is not worth taking a chance with.

Lastly, here on the Chesapeake most of us stay in the water year round and so only paint our bottoms every other year. You can typically get a year per coat out of bottom paint depending on whether you use a diver and how often.

Good luck,
Jeff
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Bottom Job question(s)

I forgot to mention, stir the paint very throughly before using and frequently during use to end up with an even copper distribution.

Jeff
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Bottom Job question(s)

Thank you all for all the great advice. It has made all the difference in my first bottom job attempt. I will be starting the job this weekend, since we are finally getting some favorable weather here in the DC Metro area. All the responses have sparked a couple of additional questions. With regards to sanding is this something that is easily done with a simple electric sander or by hand? Rollers - since the paint is toxix are special rollers required or can I simply go to Lowes or Home Depot and by several there? If I do not use both cans of paint will I be able to save the unused can for next year?
Thanks in advance for all your great advice.

Rookie

PS: Jeff we are in Harrington Harbor North. Where are you?
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Bottom Job question(s)

One thing I learnt years ago from the glass and awlgrip guys in the yards from St. Thomas to Southwest Harbor: DON''T bother to wipe down with acetone after sanding raw glass, epoxy, paint or bottom paint. Clean with air under pressure and tack rag, if you must. All you do by wiping with acetone, and, yes, I still catch myself doing it occassionally, is spread contaminants around.
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Bottom Job question(s)

If you use an electric sander (like a handheld Makita) you''ll be there all day. If you do it by hand you''ll be there all weekend.

See if you can borrow/rent a pneumatic rotary sander that takes 6" sanding discs. Your progress will be a LOT faster. Use 80 grit and a gentle touch, just enough to rough up the old paint. Also a lot quieter and lighter then the electric sanders (your arms will thank you at the end of the day).

Also be sure to check with the yard if you need to have a vacuum attached to the sander, I believe Herrington Harbor N is a "Maryland Clean Marina" and may require it.

Use a 1/8 nap roller to roll it on.
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Bottom Job question(s)

Rookie,

One thing coming out in these posts is the difference between racers and cruisers. If you plan to race, follow Jeff''s advice of fine grit sandpaper. If you are a cruiser (as am I), sand with 80 grit paper -- which is what most paint manufacturers recommend.

The roller needs to be solvent resistant, so buy it where it''s cheapest (probably anywhere other than a marine store.)

As for compatibility, the West Marine catalog has a good chart covering that - as long as you know what kind of paint is on there now. The primary problem paints are those with vinyl or teflon in them. In general, ablative paints will go over just about anything else.

I have been using Pettit ablative paints for many years and like them. As stated before, I sand/scrape off any and all loose paint to get down to a solid surface for adhesion. If the ablative paint is loose (cracking, flaking, etc.) the problem is due to the first (hard) coat of paint the dealer put on my boat when it was new years ago. That paint has lost its adhesion to the hull taking the newer ablative layer with it. All that has to come off in those areas. I feather in a layer or two of new paint in those areas to make them as smooth as possible.

I then sand the rest of the paint with 80 grit paper sicne I''m not a racer. With ablatives, I''ve found that I don''t have to sand all that much to remove the outer "dead" layer to get to a fresh layer the new paint will adhere to. That may be due to the Pettit paint I use -- or not. But there''s no need to arbitrarily sand through last year''s paint if it''s still adhering.

About painting where the jackstand pads are, I''ve done it both ways. The preference if you have the time is to have the yard move the stands so that you can do those areas properly. But a couple of times I''ve been rushed and had to sand and paint those areas with the boat in the slings. Even though the paint didn''t have the recommended time to dry, it did fine those seasons.

The last thing I do to smooth out the high spots is to go over the entire bottom with a sanding device on a pole used for drywall. Much easier than hand sanding and you can buy varying grits of sanding screens for the head to suit your needs.

With two gallons you will have paint left over and it will keep until next year. I put a piece of plastic wrap inside the can right on top of the left-over paint to provide some protection, and that works pretty well.

I sail the Chesapeake, too, out of the mighty Patapsco river.

Finally, two sites to visit for more info:

www.yachtpaint.com (Interlux paint site)
www.pettitpaint.com
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