Zak
In Australia , the voltage ranges that are considered safe for unlicensed individuals to work on are less than 50VAC and less than 120VDC. This is for good reason primarily related to electrocution and fires. Most licensed electricians should be wary of wiring for higher voltages on a small boat where it becomes difficult to avoid water on electrical parts.
Rick
With a high voltage lithium bank like the bmw i3 pack (360v) the amperages would be relatively low so cable runs from the dinghy to a 7kw inverter on the mothership would be not need to be oversized (less than 20 amps of current at peak load).