Hamilton Jet HJ212, Installation And Service Manual

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Installation and Service Manual
Appendix
Ahead, Zero Speed and Astern Controls
"Astern" and "zero speed" are achieved by re-directing the jetstream. If the reverse duct is lowered fully, all
of the jetstream is re-directed back under the vessel giving "maximum astern thrust". If the reverse duct is
lowered partially, the jetstream is split giving some ahead and some astern thrust. At a certain reverse duct
position the ahead and astern thrusts will be equal so the vessel will not move ahead or astern regardless of
the throttle opening. This is the "zero speed" position (this term should not be confused with the neutral
position of a gearbox when the driveline stops rotating).
When operating the Hamilton reverse control, the jet unit is always rotating regardless of the position of the
reverse duct. Any intermediate position between ahead and astern can be selected to give infinitely variable
speeds when manoeuvring.
Figure 15: Reverse Duct Positions
A Maximum ahead
B Zero speed
C Maximum astern
1 Jet stream
Power Assisted Slowdown
A fast slowdown can be achieved by quickly lowering the reverse duct while the vessel is at speed.
This procedure should only be used in an emergency.

Power assisted slowdown produces very rapid deceleration.

Power assisted slowdown should be used with care by new operators.

Do not use full helm control until the vessel has slowed.

Select zero speed as soon as the vessel has slowed.
For normal operation to "brake" the vessels forward motion:

Close the throttle.

Select zero speed or astern.

Open the throttle, gently at first until the desired braking is achieved.

Close the throttle as soon as the vessel has slowed to a standstill.

Do not use full steering until the vessel has slowed.
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