Renovations of the boat

Remise en état de l’arbre moteur


Confronted with a very important rolling noise on the shaft line of the engine during the conveyance of Noddi from the port of Les Lecques to Leucate, we know well that a look on this side is necessary.

What a surprise when we first poked our heads through the access hatch into the rear chamber, which gave us a bird's eye view of the rear of the engine! All parts are very oxidized, there is grease everywhere, the shaft is very hard to turn... We have work to do.

The first step is to uncouple the shuttle shaft. 8 bolts to unscrew, nothing too bad. The homokinetic joint which allows to catch up the misalignment between the shaft and the motor has a free side. We release the other in the same way and we take out this part weighing nearly 20 kg from the bottom of the engine hold. 

Small detail, and not the least, the engine is placed above the hollow keel shaft at this point. This means that any object sliding under the engine or shaft ends up 1.5m below in a pool of oil, gasoline and dirt. A real pleasure. To simplify access, we also cut out some CP partitions separating the engine boxes. 

The part we identify as being in the worst condition is a bearing bolted to a metal plate, itself resinated to the hull, and holding the motor shaft downstream of the stuffing box. This bearing has a lot of play and makes noise. Its removal is complicated by the impossibility to unscrew the bolts holding it to the metal plate. So once again we use the crude method: discer. But this one is really complicated. I have to cut two 12mm diameter bolts at arm's length, lying down, without seeing anything, above a pool of hydrocarbons, without dropping the part. To be on the safe side, I put a soaked cloth around the work area to limit the spread of sparks and I put a fire extinguisher nearby.

Finally everything is going well and I can breathe. 

After all these emotions, we can open the coupling journal that connects the shaft passing through the bearing to the propeller shaft. 8 nuts and a few chisel blows later, the shaft is free and the bearing too. 

The anode at the end of the shaft is removed, then the propeller using a puller. The stuffing box is removed with its hose connecting it to the stern tube. While we're at it, we remove the cover of the hydrolube ring to take a look at it. It's a winning operation since the ring is very worn, so much so that the rubber grooves have disappeared, preventing the water from lubricating the shaft and "welding" it to the ring. It was this part that prevented the shaft from turning properly. It is replaced by a new ring. 

The bearing, on the other hand, goes to an agricultural workshop to be replaced. It comes back to us rolling well. 

The constant velocity joint is in good condition, except that the gimbal bellows are pierced and let the grease from the ball joints spread everywhere. So we have to disassemble the whole assembly, replace the bellows, re-grease and reassemble. 

All parts are refurbished with a wire brush and anti-rust paint.

The cable gland, with braid, receives new ones (4 as original) and its hose is replaced by a reinforced and longer one. 

As we spend time in the hold, we also notice that the rear silent blocks of the engine have disappeared. The metal shaft is still there, but the rubber stop has been eaten by time. This is not good for us because it is impossible to put the shaft back in place until these parts are changed. 

We then make a engine crane system with a wooden crossbar placed above the engine, in the cockpit. Rope, some knots and a car jack allow us to lift the engine enough to remove the silent blocks, whose very unusual assembly surprises us. Obviously, we will never find identical parts.

The important parameter is the height of the motor in relation to the hull, which guarantees the alignment of the motor with the axle, so we use the modern silent blocks indicated for our motor to respect this parameter. To adapt them to the existing assembly we have to modify the mounting plate and adjust some other details. The motor is then lowered and fixed. 

After this setback, we recessed the shaft into the stern tube and put the gland in place. The bearing is reattached to the metal plate and we take care to place homemade rubber stops between the two to limit vibrations. The constant velocity joint is put back in place between the reverser and the bearing. 

Ne reste plus alors qu’à enfoncer l’arbre côté hélice dans le tourteau d’accouplement du roulement. L’opération est compliquée car c’est un emmanchement conique. Elle est sûrement réalisée à l’origine avec une presse. Après plusieurs coups de masse infructueux, nous avons une idée. Nous plaçons deux entretoises métalliques de 2mm d’épaisseur dans chacune des fentes du tourteau. Puis nous serrons les écrous en sens inverse, ce qui permet de venir les bloquer au bout sur l’entretoise et d’écarter les mâchoires du tourteau. En gagnant ainsi du jeu et en enfonçant petit à petit l’arbre tout en serrant les écrous, nous arrivons à emmancher complètement l’arbre. Cerise sur le gâteau, l’encoche pour la vis pointeau tombe parfaitement en face du trou !

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