Driveshaft: To Bond or Not to Bond?

Driveshaft: To Bond or Not to Bond?

Post by Bob Fif » Sat, 25 May 1996 04:00:00

I am planning to install a new  small diesel in my sailboat. The previous
engine  was isolated from the shaft by a *** coupling. I used zincs on
the shaft and strut,(both bronze), but both shaft and strut were not
bonded to anything else. My shaft and strut zincs seemd to deteriorate
rather quickly, (50% in 3.5 months).

I have received conflicting advice on whether or not the new installation
should  have the driveshaft bonded to the engine, or not. Some people in
the business say that it's best to keep the shaft separate from the rest
of the system, others say that it is important to have electrical
continuity from the shaft to the engine, (and consequently to most other
metal on the boat).

I checked my reference text, Nigal Clader's book, on marine  mechanical &
electrical systems, but his advice seems equivocal. He "suggests" that
shaft zincs on a bonded shaft will protect a bronze shaft at the expence
of an iron engine block.

Do any rec.boaters have any practical advice on the subject?  Thanks in advance.

Bob

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Brown University                Geological Sciences