Chapter 7 TPD1317e
Page 54
(c) It is important to include the propeller shaft in the bonding system, as the electrical path through the
gearbox is not effective due to the gearbox oil acting as an insulator. The electrical connection to the shaft may
be made by means of graphite brushes riding on the shaft or a braided battery strap may be used as illustrated
below.
In either case the shaft earthing system should be connected to the bonding system to which the engine and
the shaft log (if metal) are also connected.
Note: Strap should make contact with 90
o
of shaft circumference.
(d) Before the boat enters service the effectiveness of the bonding and sacricial Zinc anode system should be
tested, both when at rest and with all systems (including engines) in operation, by a specialist in this eld.
Note: This section on bonding covers a typical system and has been included for guidance purposes only. It
may not be appropriate for your boat. As installations vary it is advised that specic recommendations from a
specialist in the subject of electrolytic corrosion are obtained.
One way to earth the
propeller shaft
Connection to
common bonding
system
Battery earthing
strap
Ahead