Roger Long wrote:

Is there any reason to consider using dual purpose or a one starting, one deep cycle set up with a 20 hp Yanmar diesel? I would think the starting loads on the small engine are low enough that two deep cycle batteries would do fine.



Are you asking the proper question?
If you have deep discharge batteries for cruising power in lieu of
engine, then you might need to consider being practiced at starting by
hand lest you find yourself without adequate battery to run whatever
including starting the engine. If you have a small engine, keep a small
starting battery for the task... Many production boats in this area
(Great Lakes) have the dual battery configuration successfully, and
occasional white knuckles.

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