Alamarin Jet AJ 160, Operation And Maintenance Manual

Page: 17 / 40

17 Operation and Maintenance Manual
Version 1.5 Version 1.5
If cavitation is apparent, the following things
should be checked.
Check through the inspection hatch that:
1. The grass rake (figure 2.6.1-1) is not
clogged (by grass, reed, plastic, stones etc.).
2. There are no extraneous objects in the stator
or nozzle unit or the impeller (figure 2.6.1-2)
(rope, reed entagled in the drive shaft, stones
in the outlet port)
3. The impeller (figure 2.6.1-3) is not
damaged. It should be smooth and it should
not have any sharp cuts.
If the boat runs slowly even though the engine
runs on high revolutions, find out the cause.
Ventilation produces similar symptoms as cavitation but is caused by different reasons.
Ventilation is created when air gets to drift into the intake duct. The air causes the
impeller to lose grip and the thrust weakens. Ventilation can be heard as a similar sound
as cavitation.
Ventilation can be caused e.g. by the following things:
- The inspection hatch cover is open or a seal is damaged.
- The installation height of the jet is wrong, air is allowed to pass along the surface of
the cavitation plate into the intake duct.
- During installation, places accordant with the instructions have not been sealed.
Figure 2.6.1-1
Figure 2.6.1-2
Figure 2.6.1-3
2.6.2. Ventilation