Bosch Deep-cycle Marine 31

Bosch Deep-cycle Marine DCM31 marine batteries are carefully engineered to provide the optimum balance between starting and deep cycling duties.
They are also thoroughly insulated to protect against the high frequency vibrations created by rough sea conditions.
 
DCM is designed for heavy duty cycling to have enough cranking amperage for starting and sufficient reserve power to keep the electrical accessories running. 25% longer life for 50% discharge.
 
Source: Bosch.