Hi: The reason I was asking about the Johnson Pump unit was the sensing
unit had no moving parts. A feature that I find appealing for stuff
that live in a bilge. Not sure of the technology. But the article
description mentioned some electrical magic that I do not understand.

Andina, thanks for the link. The Yandina web site is good one for an
electrically challenged person as myself. Five bilge areas?!?!? Must be
a long boat.................
Bob.