Most people opt for varnish over polyurethane because of price. All the
high dollar boats have a insulator/sealer/polyurethane topcoat system.
Stuff is beautiful and last forever.

--
Shield Finishes and Nauticoat Marine Finish Systems
www.shieldfinishes.com
"Mike G" wrote in message
ews.com...
In article .com,
says...
Used Urethane to cover the sole of the yacht. Can it be used in other
places in the interior (less UV than outside) or is varnish the only
way to go.
From what I have been able to discover Urethane will give a harder and
longer lasting finish than varnish. Will it look as good in 2-3 years.
Tony
S/V Ambrosia



Hopefully you have used a spar/marine type varnish. The spar/marine
varnish is what is know as a long oil varnish. That is, it contains a
higher ratio of curing oil to urethane resins then a non marine varnish.

This actually makes it a bit less hard and brittle then a non marine
varnish. A desired property that allows it to better accommodate the
movement of wood that is exposed to an exterior environment, and, of
course, there is the UV blockers found in marine varnish.

Since you are on a roll you are probably best off continuing on with the
varnish for the interior.

Note, the UV blockers in marine varnish loose their effectives after
awhile. Expect to renew the finish every year or two, depending on the
amount of exposure. If you wait for the point where you can visibly see
the varnish breaking down it has started to loose it's grip on the wood
and will most likely be cracking a flaking. Just over coating those kind
of flaws usually looks like hell and for appearance sake you would
probably end up having to strip the stuff.

Truth be told, urethane resins form a more brittle surface then the
resins used in old fashion varnish. If I were doing the job I would have
spent some time, if it is still available anywhere, hunting down a non
urethane spar/marine varnish. Long oil non urethane varnish would be
just that little bit more flexible the the urethane.

Hope it helps


--
Mike G.
Heirloom Woods

www.heirloom-woods.net