so the old boat had a raritan made in NJ that lasted 25 years. the new - to - us boat (an 05, 2007 purchase ) came with a claimed 'top of the line ' indel marine 'basic' hot water heater with stainless steel tank, 'double overheat' thermostat protection, adjustable temp, replaceable gaskets. (very $$$ but it was OEM.) in 2016 i started getting inexplicable leaks into the bilge from the h w heater-- not from the hoses, but from the tank gasket.(diagnosed with a cheap water sensor from lowe's.) Rx: bought new gasket ($1$ of rubber for 52$.) Pulled the cover plate to fit a new gasket, found the cover plate had warped so much from high heat the tank was unusable.. bought a new tank summer 2017 , same model $550 . At yesterday's pressurizing of hot water tank --o NO ! another leaky gasket. I have yet to pull the new tank (to see if it warped its cover plate too. ) Did another 2 thermostats fail? what's the electric test to diagnose a failed thermostat? this unit has TWO thermostats-- how could both fail simultaneously so as to heat the tank so much the stainless cover plate warped again??? ideas??