Painting : Boat Painting - Interior

Painting Techniques.

Interior

From article by Don Casey :

For interior wood brightwork: Oil gives warmth and beauty, is easy to apply, holds up reasonably well. But if not maintained regularly, it turns dark and ugly. Varnish is almost maintenance-free, doesn't harbor dirt or mildew, not stained by water, lasts a long time. But initial application requires more work. Applying varnish: Project adjacent surfaces with tape and sheeting. Remove cushions that might absorb sanding dust. If bare wood has dark spots or water stains: wash with detergent, rinse, bleach with oxalic-acid, let dry, vacuum, rinse with borax, sand, vacuum. Don't use two-part wood-eating cleaners. If previously varnished: repair damaged areas by sanding and varnishing, dry, sand with 220. If removing bad old finish, use heat gun and peel with sharp scraper. No chemical stripper. Hand-sand, don't use power sander. Sand with the grain. Use polyurethane varnish, with foam brush, thin the first coat, do most coats with gloss and last two coats with satin. Always use paint with mildew inhibitor. Paint all inside surfaces, and repaint every year or two, just to keep mildew away. Paint with interior latex housepaint (dries quickly, and doesn't mildew, because it "breathes").

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Bottom

Why paint the bottom ?

Growth on bottom would slow the boat down. (But frequent diving underneath to scrub it off would control this. And even if you paint, you'll still have to dive to scrub off the propeller.) Some barnacles attach so firmly that they etch into the gelcoat.

Types of bottom paint:

Biocide paints: release toxins (usually copper) that kill life: Ablative / soft / sloughing: somewhat water-soluble, so outer layer washes off and exposes more biocide. Two types of ablative: Simple ablative. Co-polymer ablative: better control the rate of release. Hard leaching: not water-soluble, so biocide leaches out at a fairly consistent rate. Foul release paints: make surface so smooth and slippery that life can not attach to it. Any type may also have an anti-slime agent added to it, to kill soft growth that would cover the surface and prevent exposure of the biocide.

From bottom paint test article :

"This year's test, like those of recent years, shows no clear link between copper content
and effectiveness."



Underwater metal needs priming before painting with anti-fouling.



To determine type of bottom-paint on the hull, wipe dry hull with a wet cloth.
If lots of color comes off, it's soft/sloughing/ablative paint.



Any type of paint requires sanding the old paint down until what is left is
solid and adhering well. You don't need to sand down to bare fiberglass/gelcoat,
maybe unless your old paint is ablative-type and your new paint will be hard-type.



From bottom paint test article:

[Caveats: a 5-month test, with no motion of water over the test panels:]

"Less expensive paints without anti-slime additives held up just as well [as anti-slime

paints]
in our testing."



When the boat is hauled out, scrub the bottom right away;
the things growing on it will be much harder to remove once they dry out.
And if you're going to bottom-paint, scrub with something that
will sand/roughen the surface (bronze wool, brushes dipped in sand).


Lots of problems with Dolphinite Go Fast bottom paint;
comes off in sheets, or doesn't prevent major growth.


From Preston Gazaway :

A quick and dirty way to determine the square footage of your bottom is: 0.75 x length x beam

If your old bottom-paint is adhering well, and you're putting
a compatible kind on top, don't do much sanding. Just rough
up the surface, and get rid of any loose or soft areas.
You certainly don't want to risk taking off
any gelcoat.



Tips from Judy on "Quest":

If putting on multiple coats, first edge with multiple layers of tape too. After applying

each
coat, pull off one layer of tape. That way, you're not trying to tape next to a wet
edge of paint, and you're not pulling a layer of tape off from under several dry coats of

paint.
Also, use a smaller roller; a very wide one is too heavy when loaded with heavy bottom

paint.



Steps done to paint bottom when I was in the yard 1/2003:

Haul out. Pressure-wash. Put up on blocks. Immediately scrape any areas not hit by the pressure-washing, or not done well. Let dry for a day. Grind paint off any spots that need repair: gouges through gelcoat or into laminate. Should have washed those spots, but I don't think we did. Apply repair filler to those spots. An hour after applying repair filler, apply bottom paint to those spots, so filler and paint bond chemically. Let dry overnight. Scrape entire hull to get smooth, starting with a big hoe-like scraper, then following with a hand-scraper. Apply painter's tape to waterline stripe. Paint entire hull. Let dry overnight, or for a day. Launch.

From article by Don Casey in March 2004 issue of BoatU.S. magazine:

Pressure-wash and scrape hard to see if base paint is loose and needs to be stripped. If so, encourage pressure-washer to remove loose paint. If you do stripping, use marine stripper; non-marine can hurt gelcoat. Best to do some sanding even if base paint is solid. Avoids buildup that leads to flaking. Stir bottom-paint very well; use a power-shaker if available. Pour half into a mixing bucket for better mixing. Get all copper up from the bottom of the can. May take up to 15 minutes of hand-mixing, but don't skimp. Use thin-nap roller, and roll on in vertical stripes. Stir the paint again before each time you pour more into the tray.

Bottom-stripping:

Bottom-paint stripper articles in 9/2000 and 11/2006 issues of Practical Sailor. From George S on Cruising World message board: Peel versus Bead Blasting: I had my '85 Pearson 303 bead blasted last spring [2000]. It had all the original bottom coats and looked like a "Moonscape". Two professionals did a good job right down to the bare gel coat - looked like there was NO original barrier coat - just paint. They didn't overdo the blasting and left remnants of paint without damaging the glass. However, the blasting exposed a few hundred small voids (air bubbles) from the orig glass lay up of the hull. These were NOT blisters, no trapped oil or gunk in the 1/32 - 1/16 inch sized holes. I had to squeegee/fill the voids with Interlux watertite epoxy (good stuff for sanding - not hard like Marine-Tex), then sand, fill, etc several times. Then barrier coats + bottom paint, etc. Final verdict - The blasting cost me $650+ and a lot of additional work that I don't think I would have to do if I peeled it!!! If I ever have to do it again, I would take the slower peel route and probably do a better job in the end. The yards like the blasting 'cause it's faster - not better. From Les Blackwell on Cruising World message board: I used Peel Away on my Hunter 35.5 and it was great. It took several years of hard finished bottom paint right down to the fiberglass. I bought a five gallon bucket of the stuff from West Marine for about $300. But we had to buy more paper to cover -- they didn't provide enough paper for the 35.5 hull size. However, we worked in cool northwest spring weather and left it on overnight. Scraped off easily the next morning. I agree with Practical Sailor -- it appears to be the best on the market at this time. Good luck on an unpleasant task. From Brendan Sullivan on Cruising World message board: I stripped 24 years worth of bottom paint with PeelAway last spring. I tried both PeelAway marine strip products: PeelAway Marine Safety Strip and PeelAway Maine Strip II. One was about $100 per five gallons and the other was $230 per five gallons. Each worked well; I almost think the less expensive one was better. You will need more paper than comes with the five gallon drum, so be sure to pick that up ahead of time. I went through a five gallon container of each product (10 gallons total) and could have used another gallon. The product is very temperature sensitive - the warmer the better. I used it when nights dipped into the high 40's/low 50's and did not get the full effect of the chemicals. If you can wait for the warmer days/nights you will have better results. My technique was to apply it on a Friday evening then scrape on Saturday. One big mistake I made when using it was when I started to scrape the paint off I tackled a large section - the paint was loose and it left a watery residue. By the time I went back to wash down where I first started scraping, the paint residue dried almost harder than before I started. This meant more PeelAway! So I got smarter and worked on smaller sections and washed off the paint residue before moving on to the next section. It is a very labor-intensive and time-consuming job. If I were to do it all over again I would consider having the bottom sandblasted or professionally peeled. I figure with the peelaway materials, drop clothes, applicator brushes, etc it cost me $500 plus three weekends to get a 26 foot Pearson with 24 years of bottom paint down to bare gel-coat. It was my first boat project - so I probably was a bit slower / less efficient than most people. Other tips: The more airtight and fewer air bubbles between paper and chemical the better. Paper comes in 3 feet by 6 feet sheets. I cut them in half. The more expensive product has a thicker consistency. I applied it with a six inch paint scraper. The less expensive product I applied with a wide paint brush (cheap throw away kind). The thicker the coat the better it worked, but the more product needed. Need to balance this with time and money constraints. I would plan on two applications, unless you do not have many layers of paint. A painters jump suit is a must - buy a couple for $10 each and throw away when done. The more expensive product will burn your skin if not washed off. I learned this first hand - a dime size glob landed on my neck and I did not realize it for an hour. Washed it off and was left with a nice red mark for a week. Other tools required: Utility knife/razor blade to cut the paper and pop airholes. Buckets of water on hand to wash skin and tools. Roll of tape to help the paper stay on the boat in windy conditions. Drop cloths. PeelAway web site has all sorts of technical information. All in all, the bottom came out great! Peel-Away: stir it into a creamy consistency before applying. From Jim on The Live-Aboard List: I haven't used commercial stripper, I made my own and it worked well -- recipe follows. First a warning -- Gloves and goggles are a must. This stuff is nasty and will burn you or your clothing. Also air temp must be 50 degrees plus (warmer is better). You need: 1 can lye (supermarket) 1 box cornstarch (supermarket) 3 plastic buckets Misc. scrapers, rags, and clean up equipment To start -- add 1 can of lye to 1/2 bucket COLD water (basic Chemistry rule -- add the chemical to the water). Add the cornstarch to the other bucket 1/2 full of water; stir well. Slowly add the cornstarch mix to the lye mix with stirring until the mix is about the thickness of pancake mix. Glob the mix on your bottom paint as thick as possible. Go get a cup of coffee, can of beer, nap. Come back in 1/2 hr and start scraping the loosened paint; dump the scrapings in bucket #3 for proper disposal (bottom paint contains nasty stuff). It might be necessary to go around more than once. Finish with a green pad cleaning thing, rags, and warm water. Flush the whole thing with water when done several times. From Bob Johnson on The Live-Aboard List: I tried this formula. It works well on bottom paint, not at all on epoxy. It is slow acting so you have plenty of time to decide when it is "cooked" enough. I ended up using Dolphinite, which I think used to be known as Nutek. This stuff really works! Near as we couild figure it lifted/loosened about 5 coats in one application. It is very expensive $280 / 5 gallons. I ended up using about 25 gallons for a 37' tri. A word of warning - it doesn't appear to care whether it is paint or fiberglass so you do have to watch your times. 30 minutes was a minimum for me and in some areas close to an hour. Application thickness of about 1/8" worked the best, anything less resulted in a second application. From Gary on Cruising World message board: Be careful who you hire to do grit blasting. I've see 'professional' grit blasters, who contracted with boatyard customers, blast all the way through the gel coat, leaving a very porous surface to repair. I've also seen boatyards quickly paint over those porous surfaces, with bottom paint, before the customers had an opportunity to see what the blaster had done. I'm sure that such operators are a minority, but it is probably a good idea to be aware. From article in 11/2006 issue of Practical Sailor: Ways of stripping bottom paint: Scraping. Wet sanding. Dry sanding. Sand blasting. Soda blasting. Chemical strippers. [Not mentioned:] Peeling. Even a chemical stripper touted as "green", environment-friendly, biodegradable, etc produces hazmat sludge and runoff once it is mixed with the paint it is stripping off. The waste must be protected-against and disposed of properly. In the test, Franmar Soy Strip got "best choice". Apply stripper starting at keel and working out toward waterline, to keep it from dripping on you. Do scraping in same order. Read directions carefully and follow them; products have varying characteristics, and leaving them on too long can let the sludge re-harden, or can damage the gelcoat. From Dave Evans on Cruising World message board: Soda Blasting: Like sand blasting, but using baking soda as the medium. Much less abrasive than the usual stuff. Had it done on the Ranger 23 we previously owned. Took the paint right off and left the gelcoat with a slightly-abraded surface, perfect for the barrier coat. As someone else commented, it's all in the operator. They can leave paint on or dig right down through to the glass. Be there and watch (and wear ear plugs). From Johan de Bruin : Re: sandblasting Dry / wet blasting remains the only effective choice for perhaps METAL hulls. I assume you have a fiberglass hull, so the following should apply. Blasting of ANY kind destroys the gelcoat integrity. The difference between dry and wet is simply that wet takes longer for the inevitable to happen. The net effect is to make the gelcoat porous, and a porous hull WILL lead to blisters, even if you want to seal the hull again after the blasting. Furthermore, the application of the wet blasting media needs to be done at an exact angle. If the operator makes a mistake, they are not likely to tell you and will remedy the result of their errors in another method without advising you - human nature, that's all.