CORRECTING PROPSHAFT OFFSET USING THE SLOTTED HOLES OF THE ENGINE MOUNTS
Picture of a propeller shaft directly fixed to the transmission. Sailboat: Jeanneau Sun Odyssey 40.3 2006. Moored in Port Campello, Alicante (Spain), Yanmar 4JH4E,
2 ELLEBOGEN 150 (Ref. 121370-08351) and 2 ELLEBOGEN 200 (Ref. 129470-08350)
Propeller shaft is fixed to the marine engine transmission. For obvious reasons, we are interested to have a fixation is straight, so there is not an unbalance of the rotating elements. This is to say without an offset.
In a recent case, a Carlos, Sailboat owner of a Sun Odissey 40.1 who navigates Mediterranean coastline, decided to review the transmission installation as he was observing water drops on the bilge coming from the stuffing box.
He decided to disassemble the unit and and found out that the propeller shaft and the engine position were not centered . This is to say, between the engine and the shaft there was an offset. The below images show graphically the situation of the engine.
Carlos, knows that a clean bilge allows us to anticipate to mechanical problems, before they occur. When a shaft is forced, problems of different nature may arise.
From a vibration perspective, a forced propeller shaft will ruin the vibration isolation provided by the flexible engine mounts. The Fig 2 image shows an ideal installation.
HOW CAN THE MOUNTS ALLOW A CORRECTION OF AN OFFSET SHAFT?
The Ellebogen flexible engine mounts have an slotted hole of 17,5mm as shown on the below image.
The reason why this hole is horizontal is explained on is to allow a movement sideways as shown on the below video:
Carlos, replaced the packing of the Stuffing box packing and verified that the propeller shaft was rotating without major friction.
The second step was to move the engine to the correct position. This sideways movement was done using a hammer with a rubber /nylon head directly on the base of the flexible engine mounts. This has to be done carefully so we do not damage the paint of the marine engine mount.
Once the engine is on the correct position, the Carlos was able fix the transmission to the propeller shaft. Carlos, checked that the two discs were parallel, and introduced the gauge on all four sides for correct alignment as seen on the below image.
Carlos also took the opportunity to install a new Balmar 100A alternator and took the below video that shows final result.
The engine (yanmar 4JH4E) after having the shaft offset corrected, with a new Balmar 100A and a clinic bilge:
A view of the Jeanneau Sun Odyssey 40.3, with the Ellebogen mounts as they arrived to the boat.