If you’ve ever watched your boat’s fuel gauge swing wildly as the hull hits a few waves, you already know the problem. One moment the gauge reads half a tank. A few minutes later it drops toward empty. Then it climbs again. For many boat owners, the fuel gauge is the least trusted instrument on the dash. Unfortunately, fuel uncertainty on the water is more than an inconvenience it can become a genuine safety issue. Being low on fuel in a car is inconvenient. Being low on fue