Volks,
I have posted this info several times before, but don't mind
doing it again.  Now some of you have had a look at it &
more questions have arisen.
Cost:  $150 from West Marine

Rather than go into all the details, if interested go to:
www.westmarine.com

Here you will find many models of solar vents made by Nicro.
These Nicro vents have been used successfully aboard cruising
bluewater sailboats for two full decades.
They were designed to be installed in a plexiglass hatch...

Mine gave good service on my latest trip to Mexico--
with ABSOLUTELY no leaking or any other problem.
So check out West Marine for more detailed information.

Cheers,
Phaedra
'85 Wolfs Westy "Hester"