Sjouke Burry - Thanks for the suggestion of asthma inhalator &
propellors to drive model ships for making a flow meter. Also -
www.conrad.com. They have several flow sensors that could be useful,
unfortunately they are located in Germany and they do not deliver to
" Canada, USA • High insurance costs make delivery impossible " One
would think that similar sensors would be available on this side of
the Atlantic.

Richard - The clock idea is an interesting concept. I'll time my
tanks. I have a spare hour meter but I expect the accuracy would not
be good enough.

Geoff - There are two poly tanks , 50 gallons each (66" X 17" X 11")
under the salon floor. The only access withoutout cutting large holes
in the carpet etc is about a square inch at the aft corner of one
and on the fwd corner of the other. The shallow depth of the tanks
don't make for getting very good reading with most senders. I could
possibly get a Tank Tender sender in, but I don't find them very
appealing for several reasons. I do have see thru hose on the tank
outlets that gives me some idea of the levels when air is let in but
it is not very convenient.

It is winter, boat project time.

Thanks and a Happy New year to all with their helpfull ideas.