Installation Manual
N40475 Chapter 6
Page 17
Engine cooling systems
Auxiliary water systems
A completely separate sea water system should
be provided for each engine to prevent a blockage
resulting in the need to shut down more than one
engine and a typical system is shown in gure 1.
The water intake tting (4) should not project
appreciably below the bottom of the hull and it should
be situated well clear of other components such as
shafts, logs, rudders to prevent ow problems at high
speeds.
The intake ttings and pipework should have a
minimum bore of 32mm (1.25”) be provided. This
should be of the full ow type giving unobstructed
passage to the water in the open position, with a
minimum bore of 32mm (1.25”).
Between the intake tting and the sea water pump (1)
on the engine, there should be a strainer (5) which
should be easily accessible for routine examination,
and should be easily removable.
From the sea water strainer a pipe (2) should be
run to the sea water pump inlet connection on the
engine. The pipe may either be mainly rigid, of for
example copper or cupro-nickel, or exible, but only
exible hose which is reinforced to prevent collapse
should be used. Rubber hose connections in the sea
water system should be kept as short as possible.
The system must be sufciently exible to permit
the engine to move on its exible mountings. The
sea water pump connection is for hose with a 32mm
(1.25”) bore.
Care should be taken to use compatible materials
in the sea water systems, to prevent excessive
electrolytic corrosion. Systems incorporating copper,
cupro-nickel, stainless steel Type 316, gun-metal,
silver solder, and aluminium brass will generally be
satisfactory. Components made from lead, iron, steel,
aluminium or its alloys, zinc or magnesium, should be
generally avoided. Refer to section 8 on anodes.
Note: Where possible mount the strainer (5) so that
the top is just above the waterline (6) - to facilitate
cleaning.
Figure 1