Rough noise from propellor shaft ?

[Robin2]

I had not run my engine since before Christmas. The engine (Yanmar 1GM) runs fine but when I put it into gear (forward and reverse) there is a very unpleasant rough noise (like something rubbing). As this problem obviously happened while the whole thing was stationary (it was fine last November) has anyone any suggestions about what the problem might be in addition to the possibility of a piece of rope or a plastic bag being tangled in the propellor. As its a catamaran I can't lift it out for a quick look without hiring an expensive crane and I would llike to be prepared for whatever work may be needed before I dry it out.

By the way the other propellor and engine are working fine.

 

[Guest]

Hi Again, Check the stuffing box. This if you don't know is usually to be found just where the shaft disappears towards the propellor and will be a circular gland type thing with a screw down grease feeder at the top. Inside is some special square section oakum type rope paid around the shaft. The front end of this gland is threaded uptight to pack this rope around the shaft and keep it watertight. The grease nipple screws down and pushes grease into the box to lubricate the shaft so it can turn while remaining water tight. Check that there is grease in the screw cap then back off the threaded front of the gland but not too much and allow it to just drip a little bit now try the motor in gear, screw up the cap to make sure there is grease around the shaft and if all is ok retighten the front but not too much. If all that doesn't work, a cold swim to check the outside integrity costs a lot less than a crane. Good luck
Best regards Bert

 

[Robin2]

Thanks, but my system does not have a stuffing box. There is a large stainless ring on the shaft and a ceramic seal that runs against the ring. It does not require lubrication and seems to be OK.

The noise seems to be coming from further back.

 

[vyv_cox]

I once experienced something like you describe. It occurred with one of the shaft anode types that doesn't have a steel reinforcing strip inside it and was due to the bolts connecting the two halves having loosened due to corrosion of the zinc. After a while it stopped when the anode fell off. Ever since I have used the reinforced type and made sure they were very tightly bolted.

 

[Peter_the_Grate]

Do you have a shaft anode? I have experienced a noise as you describe when the anode wears and is loose on the shaft. No easy way to find out or fix it, other than drying out or lifting. Incidentally, I now put a stainless steel jubilee clip each side of the anode to stop it moving down the shaft and rubbing against the P Bracket.

 

[ChrisP]

Friends of ours had the same problem. Sounded like a bag of spoons falling down stairs with a concrete mixer. Seperated the shaft coupling and ran the engine in and out of gear. Confirmed that culprit was shaft not engine / gearbox. Boat due out soon, so ran shaft again to single out rear or intermediate cutlass bearing. Diver confirmed severe encrustacion on shafts. Lifted boat and renewed rear cutlass bearing. Barnicles had grown up the shaft and worn the rubber running surface. New bearing, back in water problem gone.

Advise running of engine in gear every week to stop the little buggers getting a hold on the shaft.

Good luck ChrisP

 

[Robin2]

Thanks, Chris

I had thought of unwanted creatures as the cause so I will buy a new cutlass bearing just in case.

I have resolved to run the engines regularly.

Other ideas are still welcome !

 

[Seapepper]

I had a similar problem last year. Cutlass bearing worn out in one year by a chalky like deposit on the shaft. Engine not run weekly, but after about 10 mins running, noise went away. On lift out, I noticed that the shaft anode was very close to the cutlass bearing. Perhaps it was preventing an adequate water flow through the cutlass.

Seapepper.