Hot water issue

I am a new Sea Ray owner . Just bought a 2001 310 Sundancer . I am having an issue with the hot water, the water gets hot but only stays hot for about 30 seconds then gets cold. Any suggestions ? Thanks

Is this immediately after you have run the engines? If it is, then relize that there could be a circulating loop extracting heat from the engines. I would then be looking at whether the hot water breaker is actually turned on. Then remove the cover at the HW tank to check for 110 volts, then check to see if there a reset button for the tank, then ring out the heater element to see if it has continuity. The tank may have been turned on without having water in it and burned out the element. Good luck & keep us posted.

The water lines could be connected backwards on the water heater and your pulling hot water off of the bottom of the water heater. Or possibly the dip tube that sends cold water to the bottom of the water heater has fallen off.

There is an anti scald valve on the front of the water heater.
Its brass with a dial with numbers on it.
You can adjust it to mix less cold water in with the hot.