Tank Tender

Before Tank Tender, you had to rely on an old-fashioned dip stick, site glass or electric float gauge to check the level of your boat's fuel, water or holding tank. Not anymore.
Tank Tender provides extremely accurate readings for up to ten tanks. Without electricity. Without leaving the bridge. Without a doubt.
Tank Tender operates on air pressure. Select the tank, then pump a small amount of air through tubing to the bottom of the tank. When the air pressure in the tube equals the liquid pressure at the bottom of the tank, the gauge displays this pressure in inches of liquid.

Website: www.thetanktender.com