> many/most types of grease are conductive. silicone grease is
> outragiously expensive.  try a search for gelstar.  I bought a gallon
> of this stuff for 20something bucks (I can't remember the exact price)
> while on a quest for a similiar product.  It is a polyofelin product
> that is suitable as a direct replacement for grease in regular
> machinery fittings, food service, and dielectric applications.  A kind
> of do-all grease that is cheap to boot. It is clear just like silicone
> grease.  Before finding this I even tried making homemade petroleum
> jelly out of mineral oil and paraffin.  That was a smashing failure.
> It does not have a stable temp. range as does this gelstar stuff.

The oil I was suggesting for filling u/w motors is light transformer oil.
Light machine oil was also tried. The motors were window wiper motors on
12V dc with a modified case. Usually people who cared put a humidity
sensor in the oil, near the bottom of the casing (these thrusters were not
orientable). When water seeps in it goes down (when given a chance, as the
oil churns around in operation). There the sensor will sense it and
command the motor controller to shut down. Actually you have some time to
do things between when the water is sensed and when serious damage begins.
The motors used in this role were mounted with vertical axles with only
one seal (the lower one) and driving large pitch radial pumps in stator
cages made of PVC plates (both the stator and the rotor). (impeller drive
style). One of those (I forget the name) multi-blade drives with variable
pitch and direction could be tried. As sold by Graupner etc.

Considering that diesel subs often had external fuel tanks open to the sea
(diesel oil floats on water) there should be nothing wrong with this
method for amateur things. Maybe not only amateur.

Peter

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