I'm thinkin' that if by chance you had a bilge with some fuel in it you wouldn't want to also have current running through the bilge water to complete a circuit.
Not to mention having grounding/bonding straps through the bilge with one of those hooked up.
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1985 Wellcraft V-20, Evinrude ETEC 150: SOLD
1979 Marine Trader 44, twin Ford Lehman 120s
2006 Panga 14, Tohatsu 20
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