painting the bottom

[bridma]

I talked to two professional boat body shops for getting my anti-foul paint put on. My boat has always been trailered by the previous owner, so it has never been painted before. One shop said, two coats of primer and two coats of anti-foul topcoat is fine, it is what they do on all new boats, and it lasts for 3 to 4 years. The second shop said, Interlux guidlines say, three coats of primer and three coats of anti-foul topcoat are required. He definately recommends do not go with just two coats! Both shops have excellent names in their community and the boating world, so I'm confused. Do I go with two coats? Is the second shop correct, that I need three coats? Or is he just trying to upsell me?

Martin.

[Tug]

I bottom painted my boat for the first time last year..yes it was confusing to me also until you do it the first time.I got alot..alot of good advice from other members and it turned out i was not difficult as i thought it was going to be. Basically the number of coats is determined by the kind of primer and top coat you buy.The instructions are on the can as to how many coats that are needed and the interval between each coat.Mine required 3 coats of primer...i put on four and if i remember correctly i put on an extra coat of top coat as well. Big job if you do the job yourself.( hard on the back and knee's ). but you can use the money you save on painting the boat yourself on gas.

[ghone]

Hi Martin I am assuming you will use Micron CSC which is one of the best for BC Interlux states one coat of no sand primer YPA200 then 2 or 3 coats of CSC. Unless you want to barrier coat first. With the small risk of the c dory blistering, I didn"t do a barrier coat on Kerri On. I did a coat of the no sand primer after a thourough solvent wash and scratch sand with 80 grit. With spending a lot of time on the trailer and then in both fresh and salt water, the bottom is perfect still. Easy to maintain also, just sand and roll on another coat as needed. They may be trying a little overkill, it is quiet in the yards so they are trying to fill their time, I betcha. George

[thataway]

The 2009 should have been laminated with at least several layers of vinyl ester resin under the gel coat. You are in cooler water, so less chance of osmotic blistering. However, there has been some lifting or blistering of the gel coat on some C Dorys. Some of this has been in cool water, not the same as the osmotic blistering in the laminate. I cannot say that your boat would or would not get blistering. But if it occurs, you may be looking at somewhere between $5,000 and $7,000 repair job. So I personally think it is worth doing the epoxy primer first. This is a barrier coat--and usually 3 coats. I generally put on two coats of bottom paint on the bottom and three coats on the sides--the sides are more likely to get scum or growth. Go with a bottom paint which has proven to be the best in your area.

The epoxy system of Interlux--Interprotect 3000 is what we use.

[matt_unique]

If the hull is bare, I would opt for the extra insurance of epoxy barrier coat prior to ablative bottom paint. I've never seen a paint that will last 1 season let alone more...that is until this past season when I applied Pettit Ultima Eco ablative. After 11 years and many different paints I finally found one that lasts a whole season!

I would opt for 2 coats of epoxy barrier coat and 2 coats of ablative paint (obviously proper scuffing and cleaning between epoxy coats and then of course the paint).

[Sunbeam]

If you are looking for barrier-coat type protection, I believe Interprotect currently recommends 4-5 coats. They are actually looking for a specific dry film thickness (DFT), but apparently in their experience, 4-5 coats tends to provide it.

You can see that here:

http://www.yachtpaint.com/usa/diy/products/primers/interprotect-2000voc.aspx

There is also more on their product data sheet. I have occasionally found Interlux's various bits of literature and data sheets to conflict, in which case I call them, which can sometimes help to clarify.

Thinking back, I seem to remember that in the past Interlux recommended 2 coats of Interprotect if it was "just" going to be used as a primer/tie-coat (for which it works well), and 5 coats if it was also intended to do the job of a barrier coat. Perhaps that's why some boatyards are (still) recommending two coats (I put "still" in parenthesis as I have not done enough current research to know if the 2-coats/primer is still valid or if it has been changed).

I have found it is absolutely critical to carefully prep any never-before-painted gelcoat in order to remove the mold-release wax (even when a boat is many years old). Skimping there often seems to lead to adhesion problems later (i.e. not using a clean towel for each swipe, etc.).

[bridma]

Thanks guys for all your input. I feel more confident now in putting questions to the paint shop, (which ever one I choose).

Martin.

[thataway]

It depends on the product for Interlux--the 2000 is 4-5 coasts and the 3000 is 3-4 coats--try and build 10 mil at least. A good painter can get the 10 mil in 3 coats.