Instruction manual

PROFICIENCY IN SURVIVAL CRAFT AND RESCUE BOATS OTHER THAN
FAST RESCUE BOATS
9 11
The outboard motor cooling system is the part of the engine most likely to
cause problems due to salt, sand and dirt entering the system. Water pumps
should be inspected and the pump impeller changed every 200 hours of
operation or once a year, whatever comes first.
It is important to keep an eye on the tell tale water stream as a drop in flow
is likely to indicate a problem with the cooling system. It could be a blockage
around water intakes (plastic bags in the water are a common cause), sand in
the system, water pump failure, damaged pump impeller and so on. It may also
simply be a blockage of the outflow (sand) from the tell tale although the engine
cooling system is operating correctly.
Flushing the cooling system with fresh water
You can help prevent some of the problems caused by salt buildup in and
around the motor by washing the body and flushing the cooling system with fresh
water after use. To clean the cooling water passages, mount the motor in a tank
partly filled with fresh water (water level above the anti-cavitation plate). Put the
motor into neutral, start and run at low speed for a few minutes. This procedure
should be carried out at least once every month.
If possible, run the engine in fresh water on completion of each trip.
1. Water surface 2. Lowest water level
Fig. 9.14 Cooling system
e) Fuses, Batteries, Propellers, Zinc anodes
Fuses protect electrical wiring and equipment from damage or fire due to
electrical overloads. A fuse is designed to melt when overheated due to
excessive current flowing through an electrical circuit. The circuit becomes open,
no more current flows through it and therefore the electrical equipment is
protected.