Perkins M115T - 5 Engine Cooling Systems; Raw Water Systems

TPD1317e Chapter 5
Page 25
Engine Cooling Systems
5.1 Raw 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.
The water intake tting 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. If
desired the rear edge of the water intake may be allowed to project more than the front, by no more than 6mm
(0.25”) to give a slight scoop effect, but if this is done it is necessary to locate the tting so that it cannot be
inadvertently partially rotated.
The intake ttings and pipework should have a minimum bore of 25mm (1”) (see gure 1). Inboard of the intake
tting a sea cock must 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 25mm (1”).
Between the intake tting and the sea water pump on the engine, there should be a strainer which should be
easily accessible for routine examination, and should be easily removable.
From the sea water strainer a pipe should be run to the sea water pump inlet connection on the engine (see
gure 1). 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 and should be reinforced with a minimum of three layers of canvas.
The system must be sufciently 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.
A typical system is shown in gure 1.