Moments Of Inertia; Mainshaft Dimensions - Hamilton Jet HJ212 Installation And Service Manual

Installation and Service Manual

Moments of Inertia

A torsional vibration analysis must be carried out for the complete driveline including engine flexible
coupling, gearbox, driveshaft and jet rotational assembly, especially where a universal driveshaft is used
without a torsionally resilient member or gearbox.
It is the responsibility of the boat builder to make sure this is done by either the engine manufacturer or the
flexible coupling manufacturer.
The moment of inertia data for the jet unit is provided so that a torsional vibration analysis can be done.

Mainshaft Dimensions

1 Mainshaft
2 Coupling
3 Impeller
4 Thrust bearing
5 Marine bearing
CoG Impeller centre of gravity
HJ212 mainshaft dimensions
D1 120
D2 475
Item
D3 160
1 Mainshaft
2 Coupling
2 Coupling
3 Impeller (dry)
3 Turbo impeller (dry)
Figure 8: Mainshaft Dimensions
D4 55
D5 500
Type Mass (kg)
D6 55
Ø38.1 6.7
Ø97 0.98
Ø116 1.2
Standard 5.6
Coarse 5.4
Extra coarse 5.6
4.0 8.97
3.4 8.84
2.9 8.85
2.4 8.96
3-7
Design Basics
Polar Mol (kg.m²)
0.0012
0.00167
0.00236
0.021
0.020
0.0231
0.032
0.0293
0.03
0.0303