For a set of 21" diameter tubes that are 12m long i.e. 6m per side, they contain around 2.7 tonnes of buoyancy. As a result unless the tubes are also punctured, you would be hard pressed to actually sink. They also maintain a lot of stability unlike a hard boat, which if just the bulwarks are above the waterline has very little stability.
Wired with a fuse to the battery direct, two switches on helm, one operates a 'on' function, and the other operates the 'auto' function. When leavig the boat overnight simply turn off isolation switch as normal so no power is going to engine start or house battery and switch auto bilge switch on.
Tickler
