posted 01-23-2006 12:16 AM ET (US)
On older Boston Whaler boats, at least up until 1990, the fuel tank and all other metal components in the fuel system were bonded together with a green 10-AWG conductor. Included in this bonding system was a sintered bronze electrode mounted on the transom below the waterline.Sometime after 1990 the design was changed and the separate grounding electrode on the transom was eliminated. It is assumed that the fuel tank system was thereafter bonded to the battery negative.
If an electrical sender is involved in the fuel tank level indicator, you will probably need to bond the fuel tank to the battery negative. I would do this with a 10-AWG conductor. I would not rely on a small cable from the electrical sender to act as a safety ground for the fuel tank.