HOW TO IMPROVE ENGINE STABILITY
On recreational boats or sailboats, achieving maximum engine stability is often a challenge.
- 01.Condition / Performance of the engine
- 02.Condition of the shaft. Ensure that it is not damaged
- 03.Condition of the cutless bearing
- 04.Alignment of the shaft
- 05.Condition of engine mounts
- 06.Drive shaft coupling alignment
With the boat in dry dock, check the following points:
Condition / Performance of the engine
Bad condition of the pistons or injection valves causes the engine to run badly and this leads to excessive engine movement.
If this is not fixed, the engine will never run smoothly.
Condition of the shaft. Ensure that it is not damaged
Due to aging or other circumstances, it is possible that the shaft becomes warped. A bent shaft rotates out of alignment and this causes friction in the stern hole which generates excesive engine movement and causes water to enter the boat.
As a result, the shaftshudders and the movement is transmitted to the engine.
This causes premature deterioration of other components.
Generates excesive engine movement and causes water to enter the boat.
Condition of the cutless bearing
Due to the rotating movement of the shaft, the cutless bearing will wear out.
This leads to anoffset of the shaft, causing lateral movements and causing an erratic rotation.
As a result, the shaft shudders and the movement is transmitted to the engine.
Alignment of the shaft
Before coupling the shaft to the transmission, it is important to correct its position. The shaft should be as central as possible to the stern hole, to avoid rubbing.
Misalignment can cause water to leak into the boat.
There are different methods to achieve this.
(Remove after adjustment)
Condition of engine mounts
Once the entire line has been checked and rectified if needed, the condition of the engine mounts isvery important. These flexible mounts are designed to absorb engine movement and to avoid vibrationbeing transmitted to the hull.
Each engine needs specific engine mounts depending on its power, weight, center of gravity and transmission.
As a result, they lose height and absorb less vibration, causing misalignment of the shaft and a decrease in performance.
Over time, these mounts deteriorate and lose their elastic properties.
It is recommended to replace the mounts every 4 years or after 1000 hours of use.
Drive shaft coupling alignment
For this, the engine will have to be adjusted on its axis in all directions. It is important to fit the engine to the shaft, not the shaft to the engine.
This can be done by adjusting the levelling nut of the mounts.
If it is necessary to raise the engine higher, the use of shims is recommended.