I think you have answered your own question. To the best of
my knowledge ball valves are not acceptable for seacocks.
Not sure why. That may be why thru-hulls and seacocks use
straight threads. So ball valves won't fit. I've never had a seacock
bolted to the hull. Normally the thru-hull is bedded and secured with
the retaining ring and the seacock is just threaded on. Even
though the seacock has a flange that will accept bolts, the flange
has always just floated.

Doug
s/v Callista

"Trent D. Sanders" wrote in message
om...
We replaced all the through-hulls on my Islander 29 with new bronze
through-hulls and bronze/stainless ball valves. The threads on the
through-hulls were straight threads, while the threads on the ball
valves were tapered [pipe] threads. As a consequence the ball valves
only tightened down on the through-hulls by about 2 "turns". The
yardman that did the job said that was the "accepted practice" and not
to worry about it.

But,,,, in this month's issue of Good Old Boat's newsletter supplement
there's this,,, "You must use straight threads on both the valve and
through-hull, or tapered on both. Mixing tapered and straight threads
is the worst thing you can do, and sadly it is [or was] common".

So, my question is,,,, does anyone know where to obtain
bronze/stainless ball valves with straight threads? Easier to replace
the ball valves rather than the through-hulls.

I'd use proper seacocks but they require bolting to the hull which
would be difficult with a fiberglass hull.

Thanking you in advance,

Trent Sanders
S/V Cimba
Marina Del Rey
Southern California