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General
The following features are necessary in any marine
cooling system.
Intake through-hull strainer (seacock cover) Install a
screened strainer to prevent entry of foreign objects.
Accepted types of through-hull strainers are those of the
perforated, slotted-hole, or unrestricted-hole design.
See Figure 6-8 for examples of typical strainers. The
selected strainer must have oopening(s) that are equal
to or greater than the inside diameter of the waterline
hose to the seawater pump. Do not align the strainer (in
relation to direction of travel) with the propulsion engine
intake. See Figure 6-7. Flush mount the recommended
through-hull strainer. If the selected strainer is of the
slotted-hole design, install it with the slots parallel to the
direction of vessel movement.
An intake through-hull strainer must not be of the speed
scoop or cup design which can cause a ramming effect
and force water upward, past the seawater pump, and
into engine cylinders when the vessel is moving and the
generator set is shut down. Hull designs incorporating
sea chests are also not suitable for intake through-hull
strainers. A sea chest is a concave molded-in-the-hull
chamber that is also aligned to the direction of travel. A
sea chest configuration applies a positive pressure
similar to a scoop-type through-hull strainer.
Mount seacock to hull, assemble it to intake, and
ensure it is accessible for operation. Figure 6-8 shows a
typical installation. Install the canvas on the outside of
the hull and the canvas or rubber packing on the inside
of the hull. Tighten the seacock.
If using caulking to seal seacock, do not apply an
excessive amount.
Excess caulk causes incorrect
water flow and, in some cases, develops a barrier which
can force water upward, past the seawater pump, and
into the engine cylinders when the vessel is moving and
the generator set is shut down.
6-8 Installation
Cooling Systems
Position intakes in relation to vessel travel so
neither is in the wake of the other.
1. Generator set intake
2. Propulsion engine intake
3. Aft
4. Fore
1. Inside packing
2. Outside packing
3. Seacock cover
4. Direction of vessel movement
5. Typical intake through-hull strainers
1
4
3
NOTE
Figure 6-7. Intake Strainer
1
3
4
5
Figure 6-8. Seacock Installation
2
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2
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TP-5592 7/96
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