By Ben Ellison
SensaSwitch bilgepump controller
Yet another problem we experienced on Ava T. (see main story) was a sticky bilge-pump float switch. It caused the house battery to run down the night before our departure and added to our underway anxieties, as we had to leave the pump off “automatic” for fear of burning out its motor. A solution would be a no-moving-parts control like this SensaSwitch, which may never need to be replaced, let alone cleared of flotsam. It contains a pair of fully sealed solid-state Mirus “field-effect” cells that can detect water while only drawing a few microamps. The top cell turns the pump on at two inches, the bottom turns it off at 3/4-inch. You can test it by holding a finger to each cell, but I added water repeatedly, with impressively consistent results. A SensaSwitch able to handle a 20-amp, 12-volt pump costs about $35. Material Sciences is also using Mirus technology in low-maintenance tank-monitoring systems (though sadly not for fuel and long-life cockpit switches).
Material Sciences Phone: (847) 718-8082. www.msc-emd.com.
This article originally appeared in the August 2004 issue of Power & Motoryacht magazine.