[Gerry Zagorski]

Found this on another site:

COLD CRANKING AMPS (CCA)
The CCA rating represents in amps the current flow the battery can deliver for 30 seconds at 0o F. without dropping below 1.2 volts per cell (total of 7.2 volts for a 12-volt battery). The higher the number, the more amps it can deliver to crank an engine.

MARINE CRANKING AMPS (MCA)
Batteries designed for marine use may be rated at MCA instead of CCA. The MCA rating method measures battery output at 32o F., not 0o F. A battery's MCA rating will be one-third higher than its CCA rating would be.
To compare two batteries when one has an MCA rating and the other has a CCA rating. multiply the CCA rating by 1.3 for the equivalent MCA rating. Or, multiply the MCA rating by 0.77 for the equivalent CCA rating. Example:

500 CCA x 1.3 = 650 MCA
or
650 MCA x 0.77 = 500 CCA


Not sure what the cranking amps requirements are for your particular engine so hard to say if the Wally Word battery you are looking at will suit your needs as far as starting the engine but since it's a 150 2 stroker it should not be that high. Also not sure what your house load is (nav lights, fish finder, GPS, etc)

Having said all this it certainly doesn't hurt to have more then you need and if the 2 Interstates worked for you then you might want to get something as close to them in terms of MCC and reserve as possible.