Hamilton Jet HJ241, Manual

Page: 35 / 202

3.1
Section 3
D
ESIGN
B
ASICS
3.1 PROPULSION SYSTEM
DESIGN
JET UNIT SELECTION:— Jet Unit selection is a
complex task and C.W.F. Hamilton & Co. Ltd should
be consulted for advice in all cases.
3.2 HULL DESIGN
3.2.1 Hull Loads
All loads produced by the Jet Unit result from the
difference in momentum of the incoming and
outgoing water. An exception is the torque load on
the Stator Vanes as they remove the angular
momentum of the waterjet which was input by the
Impeller.
The following four cases must be considered when
calculating maximum loads:
• Full Ahead.
• Full Reverse.
• Full Steering.
• Full Reverse & Full Steering.
The load situations are described in Figure 9: Loads
on the Hull for HJ-241 Jet Unit .
While the Jet Unit loads can be readily calculated,
the Hull reaction loads are statically indeterminate.
Being dependent on the stiffness and rigidity of both
the Jet Unit and the Hull structure.
All loads are transferred to the Hull via the intake
block. No significant loads are taken by the
Transom.
The table shows the maximum loads and moments
applied at the centre of the Jet Base. (Intake Block).
C
AUTION
Not all hull shapes are suitable for
propulsion by water jets. guide-
lines on suitable hull shapes, per-
formance and engine matching is
provided in the designers manual.