Ian Malcolm wrote in
:

I'd *love* to have a sight 'glass' but there is no way I could get
enough access to the side of my tank to either read the level or to
operate the essential shutoff valves top and bottom of the glass.



Use plastic hose. Put a T in the fuel line to the engine with a little
ball valve in it you can shut off. Run the plastic hose up any bulkhead
that's level with the tank, preferably fore or aft of it so you can heel
without screwing up the measurement if you're motor-sailing.

Make some kind of cap for the open end of the hose and put a tiny
pinhole in the cap. This causes the leveling in the hose to be very
slow to move so it doesn't jerk around in the waves with the slopping in
the tank. The tinier the pinhole the better for maximum lag! Make sure
the pinhole is ALWAYS far above the tank unless you're pitchpoled or
broached when it will be the least of your worries.

To read the guage, open the valve, let it settle a few seconds through
the pinhole, close the valve, read the guage. Leave the valve closed
except when you want to read the "sight hose", which is always safer.

With the pinhole's lag on the pitching, it doesn't have to be on the end
of the tank, but the closer the better, of course.

If you have to mount the hose where it's hard to see, put a styrofoam
colored ball that's smaller than the hose hole, of course, into the hose
so it floats on top of the fuel making it easy to see the level.
Compare the hose level to your stick probing into the tank and make some
cardinal marks for FULL - 3/4 - 1/2 - 1/4 - SAIL ONLY (or OH ****) at
the bottom.

If you've got a long filler hose, make sure the open end pinhole is
always ABOVE that filler cap so the fuel can go way off scale when
someone fills it too much.

Using the hose like this, you can also make a really neat TANK FULL
alarm for filling the tank when you can't see the level. Using the
styrofoam ball to block the light stream between an infrared LED and an
infrared detector from Radio Shack, figure out where "FULL" should be on
the bulkhead mounted hose. Mount the IR LED and IR SENSOR on either
side of the hose so the styrofoam ball will block the IR light when the
fuel floats it up to that level. The IR sensor is a light sensitive
transistor you can put in a simple circuit to make an alarm beeper sound
when you're filling the tank up on deck. Just mount the beeper out of
the water splashes but where you can hear it...get a loud one. Turn it
on and open the sight glass valve, fill the tank, hear the beep, turn it
off....not rocket science but you no longer have to worry about spilling
fuel out the vent into the river, which always makes those greenies on
the dock scream and yell at you sumthin' just awful!