On Sat, 24 Oct 2009 14:33:01 GMT, Ronald Raygun
wrote:

Wilbur Hubbard wrote:

"Armond Perretta" wrote in message
...
Armond Perretta wrote (on 25 April 2009):
I have been using Pettit Trinidad on my 28 foot sloop for many years
(1981 boat purchased new). When we haul, the boat is
pressure-washed, and then in the Spring the loose stuff is scraped
off and the entire bottom wet-sanded with 80 wet-dry. I use a foam
roller and about 3 quarts per coat on this full keel boat with a 22
foot waterline. At this rate every 3 years I've had enough paint on
hand to avoid buying a new gallon.
...
This year I have decided to honor the titans of Wall Street and what
remains of the financial system by "going cheap." I took a new
gallon of Trinidad, split it in half into a new empty gallon can,
added what appeared to be about one half quart of last year's paint,
and then thinned each can to bring the volume to about three quarts
in each one gallon can. This means the paint was thinned about 25 to
27 percent, which is well in excess of the manufacturer
recommendations. In fact just about any source I can find would
disagree with my approach and advise that I will end up with less
than adequate protection. The only advantage to me is, of course,
cutting my paint cost by half.
I suppose I will find out in the Fall if this plan is practical, but I
thought I'd throw it out there to see if anyone else does it this way
or has similar experience.

Last April I posted the above looking for comments and similar
experiences.
We hauled the boat yesterday and were able to determine how the highly
thinned bottom paint performed. The short answer is: "Very well."

I would have to say that this thinning method works for me, as I am now
going to get 2 paint jobs from one gallon on this 28 foot full keel
sailboat.

Stupid, stupid, stupid!

A bit harsh, though I must say his numbers don't quite seem to add up
or, as you would say on your side of the Pond, his "math" is suspect.

He needs 3 quarts per coat, and his old system therefore used 12 quarts
(3 gallons) of full strength goop every 4 years. His new system still
involves using 3 quarts per coat, but of goop thinned to 75% strength.
In other words he will now need 2.25 quarts of full strength goop per
coat, which isn't quite down to the 2 coats per gallon (which would be
2.00 quarts per coat) he claims, unless he's going to dilute it down to
67% strength (which he may well get away with, but I guess that's next
year's experiment).

3 gallons used to give him 4 years, and if he dilutes to 67%, then 2
gallons will give him 4 years. That's not "Half Price", it's 1/3 off.
And then only if the thinner costs nothing.

What you are doing is spending more on haul outs
than you save on paint. Your system requires an annual haul out and we all
know those aren't cheap. They call this being penny wise and pound foolish
across the other side of the Pond.

But he may well be hauling out annually anyway, for other reasons, even
in those years when no painting would be needed.


I think that youse guys are confusing quantities of liquid with what
actually provides the anti fouling function - the solids.

What is happening is that the O.P. is applying a thinner then previous
layer of solids to the hull. This layer is providing the required anti
fouling function for the period between haul outs.

Since all anti fouling either ablate or expend their anti fouling
chemicals over time logically one applies just enough of the expensive
stuff to last - depending on your use of the vessel. An ablative paint
for example, seems to work best if you go sailing regularly.

In essence probably most people apply more anti fouling then they
require and then complement themselves when they haul annually and
find no growth :-)

By the way, Practical Boatowner, a British magazine, conducted a
rather extensive test of anti fouling paints a few years ago (Post
TBT) and found that a paint that worked perfectly in one local didn't
do worth a damn in another so the fact that a bloke gets startling
results with XYZ paint in one section of the country doesn't
necessarily mean that it is the best paint for another.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)