James wrote:
I need to replace some gate valves in our boat and I was looking at
Apollo Ball valves. They say that they will work with thru-the-hulls.
Since thru-the-hulls have straight pipe threads and the ball valves
have tapered pipe threads I don't see how this is possible. Am I
missing something? I know that seacocks have both straight and tapered
threads but a seacock would probably be overkill in this case.

There are ball valves that have tapered threads and seacock ball valves
that have straight threads. Apollo and Groco seacocks have NTP (tapered)
top thread and the bottom thread is NPS (straight).