No. You have an outboard - Tie the two battery negative posts together with a short jumper. Using the transom mounting bolts is the same as bolting the ground to the hull, a no-no in an aluminum boat.
Bondo, so the way I understand what your saying is to run an sufficient cable to a ground on the block of the motor then to a bus bar mounted wherever then connect my batteries to the negative bus?
His hull by default should already be grounded/bolted to batt neg through bonding wires. My stock Merc would ground my hull via two very specific factory bolted on bonding wires that intentionally bond/ground (batt neg) the transom mounting plate/bolts. If my hull was alum. that is........
However, running current through the hull or any metals that are grounded via bonding such as transom/mounting bolts, etc. as mentioned above (or even the bonding wire/s itself) is a no no.
See post #2, SilverTip is correct in his assertion
