RNLI Atlantic 85, Manual

Page: 97 / 122

Activity 9 - Propulsion and Auxiliary Systems
97
B Class Atlantic 85 Manual – First Issue, June 2017
Activity 9 - Propulsion and Auxiliary Systems
Steering system
The B-Class Atlantic 85 Class Lifeboat is fitted with the
‘Seastar’ Hydraulic Steering System as standard. It is
the same system that is fitted to the B-Class Atlantic 75
Lifeboat. The steering wheel is fitted to a hydraulic pump,
which transfers hydraulic fluid from one side to the other
of a two-way hydraulic steering ram, which is fitted to the
port engine.
‘Seastar’ hydraulic steering system
The ‘Seastar’ Hydraulic Steering System comprises three
main items:
• A combined helm and resevoir unit.
• An emergency by-pass valve.
• A steering cylinder.
As the hydraulic system operates at a comparatively
low pressure, all three items are connected with simple
thermo-plastic pipes.
It should be noted that the operating system can be
operated up to a maximum pressure of 1000psi. At this
pressure the pressure relief valves in the combined helm
and resevoir unit will lift.
A by-pass valve is fitted which, when opened, allows a
free flow of hydraulic fluid from one side of the steering
cylinder to the other.
Should a failure occur in the system, the boat can be
steered manually by opening the bypass valve and fitting
an emergency tiller to the starboard outboard engine.
Emergency
by-pass valve
combined helm
and resevoir unit
Steering wheel (helm)
Thermo-plastic pipes
Steering cylinder