How far can you stretch bottom paint coverage by thinning?

There were only two cans of paint on my yard invoice for last year
when I looked back to see how much to buy this year. That didn't seem
like very much but it is supposed to go on quite thin. According to
the coverage table on the can, I should need about six cans.

I couldn't get the proper thinner so I put it on straight which seemed
quite thin and to work very well. I ran out about half way down the
second side. I drove back to Portland and bought the last two cans of
VC 17 M Extra in the city. Saving half a can for the bottom of the
keel and under the hull supports I was able to put the recommended two
coats on the keel, rudder, and forward part of the hull where fouling
creates the most drag. It will be interesting next fall to see the
difference between the single coat and double coated areas.

If the yard last year put on just one coat, it is possible that they
could have done it with two cans if thinning could stretch it from 75%
to full coverage. Is that possible or did they just forget to charge
me for a can?
Unless the yard forgot to bill me for two cans last year, the boat
only had a single coat which might account for the marginal
performance.

BTW thanks to whoever suggested the nail holes in the lid trick for VC
17 M. Not only did it keep this very volatile paint from skinning up
in the roller tray, I was able to keep shaking the can as I went. I
poured out just enough each time to wet the roller. Being able to
turn the can all the way over when pouring also helped keep the copper
distributed.

--

Roger Long