chuck wrote:
Hello Frank,

Interesting comments.

My experience has been that it is not necessarily good or common
practice to bond all bronze through-hulls. It is rarely done in Europe,
and the ABYC makes clear that electrically isolated through-hull
fittings need not be bonded. While it is true that stray currents inside
the hull may cause corrosion of through-hulls, bonding through-hulls ".
. . causes corrosion due to stray currents outside the hull".
(Boatowner's Illustrated Handbook of Wiring by Charlie Wing)

To be honest I have no strong opinion either way, but I thought the
ABYC standard was unequivocal. In my 1998 copy they say:

"H-27.7.5.2 Metallic thru-hull fittings and drain plugs, installed
below the normal accumulation of bilge water, shall be bonded to the
boat's common ground point to minimize stray current corrosion."

Has their thinking changed since then?