Seawater Inlet Recommendations; Transom Mounted Or Thru-Hull Seawater Pickups And Hose; Seacock (Seawater Inlet Valve); Sea Strainer - Mercury 305 CID Service Manual

Seawater Inlet
Recommendations
Transom Mounted or Thru-Hull
Seawater Pickups and Hose
Water pickup must be large enough to permit suffi-
cient water flow to engine seawater pickup pump for
adequate engine cooling [30 gal. per min. (114 L per
min.) minimum]. Pickup also must supply a positive
head while underway.
! CAUTION
Do not install water pickup directly in line with
propeller, as pickup may create turbulence and
allow air to flow into the "propeller slipstream."
This will cause propeller ventilation and will ad-
versely affect boat performance.
Water pickup should be located as close to seawater
pickup pump inlet as possible and in an area where
an uninterrupted, solid stream of water will flow past
when boat is underway. Connect water pickup to sea-
water pickup pump inlet with 1-1/4 in. (32 mm) I.D.
wire reinforced hose of adequate wall thickness to
prevent it from collapsing from pump suction. Be sure
to secure hose connections with hose clamps.
Index
6A-2 - SEAWATER COOLING MODELS

Seacock (Seawater Inlet Valve)

If a seacock is being used, it must be installed be-
tween water pickup and seawater pickup pump (or
sea strainer), to allow operator to shut off the seawa-
ter in case of a leak or when boat is not in use. This
will allow the operator to flush or drain the engine, or
clean the sea strainer while boat is in the water. Sea-
cock used must have an internal cross-sectional area
equal to or greater than hose to prevent restricting
water flow. Install seacock in an area where it will be
easily accessible and self-supporting to prevent hose
fatigue.
c
Seacock (With Thru-Hull Pickup Shown)
a - Hose Connector [1-1/4 In. (32mm) I.D.] to Seawater Pump
Inlet
b - Seacock [1-1/4 In. (32mm)] Brass Ball or Gate Valve
c - Seawater Pickup
d - Direction of Seawater Flow

Sea Strainer

If boat is equipped with a sea strainer, it must be of
sufficient size to ensure that an adequate supply of
water is maintained for engine cooling. Install
seawater strainer in an area where it will be easily
accessible for inspection and cleaning. Strainer
should be installed in water inlet hose after water inlet
valve to allow operator to shut off water when
cleaning strainer.
a
b
d
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90-823225--1 1096