Number of Bottom Paint Coats

[fstbttms]

Originally Posted by thinwater

PS did a test of cleaning methods for soft paints last year. The short conclusion was don't, not until very near the end, and then very gently.

I have long maintained that the Practical Sailor anti fouling paint tests and their attendant recommendations are not worth the paper they are printed on and this is a good example of that. Ablative paints foul every bit as quickly as any other kind of paint and require cleaning every bit as often. A recommendation to not clean them until they are near the end of their useful lifespan means somebody doesn't know what the hell they are talking about, certainly not when it comes to using an ablative paint in regions of moderate to high fouling, which is where the majority of saltwater boats in this country live.

[fstbttms]

Originally Posted by thinwater

T
It's complicated. I suspect the best number of coats varies with the area. Some people want to haul every 2 years for inspection or for work that needs done. 3-4 coats are probably better in high fouling areas and for sailors that want to go 3-4 years. No one answer.

It's not complicated at all. More paint means more biocide which means longer useful lifespan. Anti fouling paint biocide is leached into the water at a proscribed rate that is determined at the factory. Putting more paint on doesn't mean greater anti fouling protection, it simply means that biocide will be leached out over a longer period of time. If you do your boating where the season is short, you may not need multiple coats of paint. If your boat lives in the water year 'round and you don't want to haul frequently (and really, who does?) then multiple coats will extend the time between haulouts. If one coat of paint provides good anti fouling performance for X amount of time, then two coats (meaning twice the amount of biocide is on the hull) will provide good anti fouling performance for 2X amount of time.

It ain't rocket science.

[sailorboy1]

So I decided to try asking a manufacturer so asked Seahawk as that's what I planning on using. So far they have responded, but didn't really answer the question and said"

"longevity is directly connected to FILM THICKNESS. If you want to achieve that mark, you might want to apply 3 coats overall and a third around the waterline."

I'm now trying to get an answer to "How many coats before adhesive becomes a problem and what are the maximum recommended coats?"

[kmacdonald]

Depends. What kind of paint?

[wcapman]

I had previously used 2 coats of Petit Trinidad but it was only lasting 2 years and was covered with barnacles on haul-out. Three years ago I was in a boatyard in Mobile. They recommended Sherwin Williams Commercial ablative bottom paint. It was 1/3 the cost of Trinidad I put about 6 coats of SW on the boat, with a red indicator coat first. Since then I have sailed several thousand miles in the Gulf. When hauled for a cutlass bearing repair last month, the bottom was clean. No slime, no barnies. The paint was still in good shape, so I relaunched as is. I don't know how thick the remaining paint is or how much longer it will last. One thing that is important is to follow the manufacturers instructions to the letter. It may be painful at $30 a day to remain in a boatyard while you wait 8 to 12 hours for paint to dry, and then 24 hours after the last coat to splash, but if there is any solvent left in the paint when over-coated or launched the life will be greatly reduced. The SW tech service guy also pointed out that painting over ablative paint that has been is salt water will probably lead to failure of the new paint due to salt entrained in the pores of the old paint. Before painting or sanding the old paint should be treated with a good salt remover and pressure washed.

[skipgundlach]

My apologies for thread drift, as I cover a great deal more ground below than merely answering the question. But, note, I'm about to enter year 6 on the first color, though there are spots where the second color is showing, now...

Do I need to strip my bottom? - Page 2 - Cruisers & Sailing Forums
for full story this appeared in...

I did a massive bottom job. You can see our bottom job work here:
Pictures: Flying Pig 2011-2012 Refit/Bottom Job

At the risk of thread drift, drying out blisters is not a matter of
exposure or heat or barns or the usual. Blisters are a product of
uncatalyzed water soluble material (UWSM). Add water and they expand
slightly. Any boat built of polyester resin (most until relatively
recently) will have some, if not a lot.

Until that's gone (not merely dried out), you'll have the risk of
repetition, even under barrier coats, as ours were after a PO had
peeled and barrier coated.

The solution (pardon the expression) is to wash it out - water, under
pressure, preferably, rinse, repeat, grinding all non-laminated areas
away as you go, until you get no more weepage. THEN you can repair and
fair. We saturated the hull with a hose one day, and pressure washed
it the next. Any time we saw tell-tale weeps, we ground the underlying
lamination voids out. After we'd had several repetitions of no-weep,
we brought in a steam pressure washer; that showed two TINY places,
after chasing which, we considered ourselves finished.

Following our repair, we used an epoxy-based fairing compound capable
of going to a full inch without sagging; we didn't ever allow more
than a maximum of about 1/4 inch. The rest we built up with new glass
and West System epoxy.

This is the fairing compound we used. It comes in one and two gallon
pails (mix batches, total 2/4 gallons):
http://www.axson-technologies.com/si...0UltraFair.pdf

An example at retail:
https://www.merrittsupply.com/produc...ltra-fair-kit/

We used cheap thin plastic cutting sheets (like a cutting board but
very thin) to mix on, and then washed them with acetone, ditto
application tools. Several hours to green, but a full day made it like
concrete, despite the expected full cure being several days. Best to
do your rough sanding when it's firm enough that you can't ding it
with your fingernail but not any more than a full day out unless you
want a great deal more work than you could have had earlier.

I learned about Sherwin Williams marine coatings from a paint pro
(boat and airplane paints) in the same yard; he used them on his boat.
They make a great tropical-waters ablative (tested in Key Biscayne),
in two mixes, as well as barrier coat, to milspec levels. Talking with
their head tech told me that there is such a thing as too much barrier
coat; I no longer recall the number, but there is a specific mil
thickness they recommend not exceeding - get a mil gauge to see how
deep any coat is as it's applied. I think we used 4 or 5 coats, in
differing colors, to alert us to any damage as well as when we ran out
of bottom paint. First several BCs were red, and final gray; first AF
black, top red...

You put on the first coat of AF as the BC topcoat gets 'tacky' - a
very limited window. That's why you'll see pix of black over gray
nearly simultaneously:

You can see the paint (barrier coat and bottom paint) portion of our
work here:
Pictures: Flying Pig 2011-2012 Refit/Bottom Job/4 - Barrier and Bottom Coats

We launched in late January 2013, and the boat has never been further
north than the fecund waters of the Charleston City Marina, mostly
being in the tremendously foul ICW at Vero Beach FL or in the Bahamas.

In that 6 or so years, it's been scraped irregularly, and, when I'm
in the Bahamas, scrubbed (ground on a falling tide, put on lots of
weights and use a hookah to breath while I take a deck brush to the
hull) occasionally.

This last trip back - after being in the Bahamas for over 2 months
without ever scrubbing - from Green Turtle Cay to Vero - took ALL the
growth off.

We are starting to show the next color down in many places; we used 2
coats everywhere and 3 or more coats at the waterline and hard points,
including the entirety of the bow-to-tip-of-rudder bottom-most line.

Based on our usage, we probably will have to pull the boat sometime
before it actually needs it, to attend to something else important,
but our FIRST coat isn't gone at close to 6 years. However, a
suggestion my buddy made, while wonderful initially, has not held up
well at all: Do the reveal stripe in brilliant white Pettit Vivid.
Indeed, it cleaned readily - but most of it in many areas is now gone,
leaving our fairing compound exposed where it happened to be, or
gelcoat, where there hadn't been damages needing attention. I think
I'd do it again, but with massive numbers of layers, as it ablates TOO
easily. Back to Sherwin-Williams...

They make two types of ablative paint. My buddy, because they didn't
have my type in stock, used the harder (presumed - designed for boats
over 10 knots rarely at rest) ablative; it still gives great service.
We use the softer ablative, designed for our type of use - under 10
knots, and frequently at rest.

Here are the relevant links for both types of bottom paint. Spec is
2-3 years, and easily-brushed slime is typical after 18 months per
their info, but we’ve gotten much longer from ours.

Copper Bottom Anti-Fouling Paint #45 - Protective & Marine – what we
have, available in 4 colors - I don’t recall now whether I had to go
to FTL for it, but I THINK they inter-office shipped it to the local
S-W shop, as it wasn't in stock in the FTL store, and was ordered for
us.

Seaguard Ablative Anti-Fouling Coating - Protective & Marine – what my
buddy I told you about has, and he’s happy; it’s more likely to be in
stock, though you might have to go to some major marine area to get
it.

In either event, of course, you'll more likely find it in marine
areas, but it could be shipped anywhere. Ours was $85/gallon in
5-gallon buckets in late 2012. I have no idea how much it will be
today, but we were on the order of a third to a quarter of "marine"
products that most folks use. The only improvement I could think of
would be tin

https://www.paintdocs.com/docs/webPD...&prodno=N51B45
– ours

https://www.paintdocs.com/docs/webPD...prodno=P30BQ12
– buddy’s

They also made our barrier coat;
https://protective.sherwin-williams....3Aproduct-6939

Our prior bottom paint had been the very best West had to offer; we
got much less time from it, at massively more cost.

According to my paint pro, the US Navy and Coast Guard use it; I
certainly have been pleased.

YMMV, but at that price, and if you haul regularly, it's worth a shot.

FWIW, in the godawful areas of St. Marys GA, cleaning was a matter of
using a wide drywall taping knife (very wide spatula) and running
stripes down the hull at next to no effort. If we'd been sailing, they
might have even just ablated off, but we spent an entire summer at a
dock there (those docks are now gone courtesy of Irma). We have found
no circumstances of hard growth that would not flake right off...

L8R

Skip
__________________
Morgan 461 #2 SV Flying Pig, KI4MPC
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[sailorboy1]

The specs on that Sherman Williams paint looks good. But the stuff is a semi mystery and I haven’t found a price on line after 20+ minutes of searching

[skipgundlach]

You won't - call your local shop and get them to order it in for you. I also have a direct contact at SW if that fails

[Ringmaster]

I'm on the Chesapeake. In the spring I lightly sand the entire bottom, powerwash, then roll one thin coat of Petit Vivid on using a foam roller. I haul out every fall.

[sy_gilana]

1999 2 coats of International Micron CSC Ultra.
Life span 3 months.


2000 6 coats of Sigma Ecol Black
Life span 6 years.


2006 6 coats of Rainbow SP99
Life span 5 years (still working when hauled)


2011 6 coats of Titan HAF Autopulimento.
Life span 7 years.


2018 8 Coats of Ameron/Sigma ABC123 (@$94.00 per gal)
We will see....


That is all coats, but more at high wear areas.

[David L Lodwick]

1 barrier coat, 1 green1blue, (rolled N&S), another blue 16” at water line (E&W

[skipgundlach]

Originally Posted by skipgundlach

You won't - call your local shop and get them to order it in for you. I also have a direct contact at SW if that fails

Joe Koppleman
Marine Coatings- Florida
The Sherwin Williams Company
Ph: 904-545-4360
Joe.H.Koppleman@sherwin.com
NACE Certified Coatings Inspector-
Level II # 55058

[RobPatterson]

I voted "2" but I use non-ablative paint.

[sailorboy1]

Originally Posted by RobPatterson

I voted "2" but I use non-ablative paint.

it's OK, I figure at best 1/2 the voters fall into the conditions in post #1 to have voted

[David L Lodwick]

Originally Posted by sailorboy1

So I decided to try asking a manufacturer so asked Seahawk as that's what I planning on using. So far they have responded, but didn't really answer the question and said"

"longevity is directly connected to FILM THICKNESS. If you want to achieve that mark, you might want to apply 3 coats overall and a third around the waterline."

I'm now trying to get an answer to "How many coats before adhesive becomes a problem and what are the maximum recommended coats?"

iii use SeaHawk 2yrs+++ still on the (blue) outer coat