Lew Hodgett wrote:
"Larry" wrote:

I found the website of the really great marine head installed on a
racing trimaran that's visiting Charleston this week.

Your basic Lavac from Blakes in the UK.

Available in US from Defenders and Brendens Isle, in Florida, started
by Tom O'mera many years ago.

Uses basic Henerson MKV pump (Waste waater version of Whale 10).

Small pin hole in incoming vacuum line eliminates "stuck seat" problem
after using. (Design per Tom O.)

Next question.

The pin hole does not necessarily do the trick - it depends on the
geometry. On my setup it takes several minutes to release by itself. I
can pry it with my fingertips after about 15 seconds, but my daughter
can't do it.