Check this graph out. it shows energy consumption over a 12 hour period. The spikes are the water heater cycling on and off. It is so regular in timing and energy used it really looks like a simple timer circuit rather than a sensor-based thermostat. This same pattern repeats 24/7 so one can take out the environment as a factor in the consistency of cycling.
Sure Marine is the main support contact and they are a bit baffled and feel maybe the thermostat was swapped or not installed properly. Tomorrow, I'll open it up to find out what is in there but all I can say is it sucks a huge amount of energy that is not needed.
Is the thermostat's sensor properly seated against the tank of the water heater?
Almost looks like it tries to heat the tank and then something quickly goes wrong and it shuts back off, only to repeat the process again once the over-heat cycle cools down to a set point again.
Is the water reaching the proper set point?
Great find Don