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Power Steering 515

SeaStar Power Steering System

SeaStar Hydraulic Power Steering uses the ship's engine(s) to provide the "power" for the steering system, via a mechanically or
electric motor driven hydraulic pump. A manual hydraulic steering system, consisting of a helm and a hydraulic cylinder (ﬁtted with
an integral servo cylinder and a power steering valve), supplies the "control" portion of the steering system. Under normal condi-
tions, with engines running, a hydraulic oil supply is in a stand-by mode, ready to be directed to the steering cylinder as dictated by
the steering wheel, servo cylinder and power steering valve. Turning the steering wheel left or right makes the system go from
"stand-by" into "operating" mode and move the steering cylinder accordingly. In the event of a power source failure, hydraulic oil
from the steering helm is automatically diverted into the servo and steering cylinder, providing the helmsman with manual back-up
steering. An engine room mounted oil reservoir allows easy ﬁll and assists the in-line cooler in cooling the hydraulic oil. An in-line
oil ﬁlter helps to protect the steering system components against contaminants.
APPLICATION TYPICAL APPLICATION
Vessels up to 75 feet with 9" stroke steering cylinder and
those up to 100 feet with 11" stroke cylinder. Suitable for
single or multiple stations/engines.

FEATURES
• Effortless steering at any speed.
• Responsive 3-1/2 turns lock-to-lock (number of turns
can be varied by helm).
• Easy autopilot interface.
• Automatic manual back-up steering.

HOW TO SPEC A SYSTEM
1. Vessel size and hull type determine the kind of cylin-
der required. All boats over 70 feet in length should
have steering loads reviewed by your salesperson.
2. Engine type determines which power steering pump
should be used. If in doubt, contact your salesperson.
3. A SeaStar 1.7 helm is recommended; this will result
in a system with 3-1/2 wheel turns lock-to-lock when
9" stroke cylinders are used.
If a different number of wheel turns is desired, con-
tact your salesperson for recommended helm to
achieve desired number of steering wheel turns.

APPLICATION GUIDE FOR POWER STEERING CYLINDERS
The chart below is only a guide to selecting a steering system. A steering system maker cannot anticipate all the variables in boat-
rudder design that affect steering loads. It is the ﬁnal responsibility of the boat designer/builder to specify maximum expected steer-
ing loads. Boats over 70 feet should have steering loads reviewed. See your salesperson.
Deﬁnitions of terms used in the chart: Planing Hull: maximum hull speed normally exceeds 18 knots; Displacement Hull: maximum
hull speed does not normally exceed 18 knots.
FOR HELM STEERING REQUIRES RECOMMENDED MAXIMUM
VESSEL PUMP WHEEL CYLINDER TUBING/HOSE OUTPUT TORQUE
SIZES MODEL TURNS PART NUMBER(S) DIAMETERS FROM CYLINDER(S)
UP TO Lock to Lock (" = cylinder stroke) FIG 6564 Power Manual In. Lb. Kg. m.
Circuit Circuit
PLANNING HULLS
65ft. (20m) SeaStar 1.7 3.5 HC5801-2 (9") * ** 18,900 210
75ft. (23m) SeaStar 1.7 4.25 HC5803-2 (11") * ** 23,140 260 POWER STEERING
85ft. (26m) SeaStar 1.7 3.5 HC5801-2 + HC5802 (9") * ** 37,800 420
100ft. (31m) SeaStar 1.7 4.25 HC5803-2 + HC5804 (11") * ** 46,280 520
110ft. (34m) SeaStar 1.7 3.5 HC5805 (9" 2.5") * ** 33,065 370
120ft. (37m) SeaStar 1.7 3.5 HC5805 + HC5806 (9" 2.5") * ** 66,130 740
DISPLACEMENT HULLS (STANDARD)
50ft. (15m) SeaStar 1.7 3.5 HC5801-2 (9") * ** 18,900 210
60ft. (18m) SeaStar 1.7 4.25 HC5803-2 (11") * ** 23,140 260
75ft. (22m) SeaStar 1.7 3.5 HC5801-2 + HC5802 (9") * ** 37,800 420
85ft. (26m) SeaStar 1.7 4.25 HC5803-2 + HC5804 (11") * ** 46,280 520
100ft. (31m) SeaStar 1.7 3.5 HC5805 (9" 2.5") * ** 33,065 370
110ft. (34m) SeaStar 1.7 3.5 HC5805 + HC5806 (9" 2.5") * ** 66,130 740
DISPLACEMENT HULLS (HEAVY DUTY)
40ft. (12m) SeaStar 1.7 3.5 HC5801-2 (9") * ** 18,900 210
50ft. (15m) SeaStar 1.7 4.25 HC5803-2 (11") * ** 23,140 260
55ft. (17m) SeaStar 1.7 3.5 HC5801-2 + HC5802 (9") * ** 37,800 420
60ft. (18m) SeaStar 1.7 4.25 HC5803-2 + HC5804 (11") * ** 46,280 520
70ft. (22m) SeaStar 1.7 3.5 HC5805 (9" 2.5") * ** 33,065 370
80ft. (25m) SeaStar 1.7 3.5 HC5805 + HC5806 (9" 2.5") * ** 66,130 740
NOTE: Theoretical torque about pivot point at 35 degrees articulation with 1,000 PSI (70 BAR) system pressure.
*No. 206-8 2000 PSI Hose. Special Order
**FIG 1HYN No. MSH5 Tubing or No. 206-8 2000 PSI Hose. Special Order

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