hot water heater problems

I have a 1989 SeaRay 410 with 12 gal Raritan hot water heater ( and Heat exchanger). Water is still Luke warm after replacing both the element and thermostat. Any advice would be appreciated. Thanks.. Just Peachy

I own a 2003 40 sedab bridge. Does anyone know how to rain the hot water heater. Hot water is smelling like rotten eggs. I read that I need to drain the tank fill it with fresh water and chlorine to clean it out. Another post recommened using hydorgen peroxide. Any recommendations would be...