Sizing engine starter wire 250 HPDI

Relocated the batteries on the boat and rewiring the entire boat while I am at it. Not sure what my 2003 Yamaha 250 HPDI needs for starting and for proper charging. Is it as simple as trying to start the motor and see what it draws for amps at start up and then figure my voltage drop based on distance to select the right wire size? Or can someone out there just tell me what this motor draws so I can just get to it instead of having to rig to start. The boat is already disassembled and rigging to check for amp draw will be a big PITA. Thanks...........