Or, as another possibility, has anyone rethreaded a NPT to NPS?

I asked both a machinist friend and the shipyard and they said it
couldn't be done.

However, looking at the two half inch fittings on the desk in front of
me at this very moment, I'm damned if I can see why running a pipe die
down the first few threads of the through hull wouldn't taper it and
let it engage more than the half depth it does now.

Anybody out there got a pipe die set and want to invest $5.39 (price
of half inch bronze through hull at local store) in edifying the
boating world?

--

Roger Long