Stern Gear - how long should it last?

[shaker]

2 years ago I had the prop shaft and stern tube renewed on my boat - I'm not even sure the replacement was needed in the first place, but the boatyard who did the work recommended it should be done. The assembly now needs to be replaced again even though the boat has only run for 968 hours since that repair.

The engine mounts are in good condition. The greaser, filled with the right grease, has been used before every trip and the stern tube flange has only ever been adjusted to a level where the prop shaft can still be turned easily by hand.

I think the fault is that the engine wasn't aligned correctly when the work was originally done and that's why it's knackered.

The set up is a standard beta engine with a PRM gearbox connected through a flexible coupling to the prop shaft. The prop shaft exits through a stern tube fitted with packing and lubricated by a standard greaser.

The boatyard deny any responsibility. They say it's a wear part and it's worn!!!!!!

I disagree and I am looking for some help.

Anyone interested??

[Timleech]

2 years ago I had the prop shaft and stern tube renewed on my boat - I'm not even sure the replacement was needed in the first place, but the boatyard who did the work recommended it should be done. The assembly now needs to be replaced again even though the boat has only run for 968 hours since that repair.

The engine mounts are in good condition. The greaser, filled with the right grease, has been used before every trip and the stern tube flange has only ever been adjusted to a level where the prop shaft can still be turned easily by hand.

I think the fault is that the engine wasn't aligned correctly when the work was originally done and that's why it's knackered.

The set up is a standard beta engine with a PRM gearbox connected through a flexible coupling to the prop shaft. The prop shaft exits through a stern tube fitted with packing and lubricated by a standard greaser.

The boatyard deny any responsibility. They say it's a wear part and it's worn!!!!!!

I disagree and I am looking for some help.

Anyone interested??

 

The prop shaft and connection arrangements on modern canal boats are often under-engineered, for reasons of initial economy and of space, so shaft and bearings often won't last as well as if the job is done properly, with no extraneous stresses on the sterngear. That said, 1000 hours is a very poor life, and bad engine alignment is the most common contributor to reduced life. Impossible to comment meaningfully on whether or not you have any sort of case against the people who fitted the replacement gear, though.

 

Tim

[Tony Brooks]

2 years ago I had the prop shaft and stern tube renewed on my boat - I'm not even sure the replacement was needed in the first place, but the boatyard who did the work recommended it should be done. The assembly now needs to be replaced again even though the boat has only run for 968 hours since that repair.

The engine mounts are in good condition. The greaser, filled with the right grease, has been used before every trip and the stern tube flange has only ever been adjusted to a level where the prop shaft can still be turned easily by hand.

I think the fault is that the engine wasn't aligned correctly when the work was originally done and that's why it's knackered.

The set up is a standard beta engine with a PRM gearbox connected through a flexible coupling to the prop shaft. The prop shaft exits through a stern tube fitted with packing and lubricated by a standard greaser.

The boatyard deny any responsibility. They say it's a wear part and it's worn!!!!!!

I disagree and I am looking for some help.

Anyone interested??

 

 

All I can say is that my 20 year old ex hire shaft and gland has no discernible wear and went 11 years without adjustment (it was sonly adjusted than as part of diagnosis that eventually lead to a slight hull leak. However it does use an Aquadrive and the alignment is spot on.

 

Look at the hole in the packing adjuster. If it s worn significantly oval then the engine alignment must be questioned. If the originals are still in the boat see if you can see how the shaft has moved in the pusher. If its sideways or up then it would be easy to argue the alignment was wrong from the start. If it is down then the yard can argue the mounts have compressed or failed so the alignment should have been adjusted.

 

Maybe they have found wear in the outboard bearing which would probably indicate a lack of lubrication but I understand many shafts use a replaceable plain bearing so why the want to fit a complete new stern tube is beyond me.

[Timleech]

 

 

Maybe they have found wear in the outboard bearing which would probably indicate a lack of lubrication but I understand many shafts use a replaceable plain bearing so why the want to fit a complete new stern tube is beyond me.

 

The most common sterngear found in inland waterway chandlers has the bearing as part of the tube itself.

Whether the tube is a proper bearing bronze, or manganese bronze/brass, I'm really not sure.

 

Tim

[nbfiresprite]

2 years ago I had the prop shaft and stern tube renewed on my boat - I'm not even sure the replacement was needed in the first place, but the boatyard who did the work recommended it should be done. The assembly now needs to be replaced again even though the boat has only run for 968 hours since that repair.

The engine mounts are in good condition. The greaser, filled with the right grease, has been used before every trip and the stern tube flange has only ever been adjusted to a level where the prop shaft can still be turned easily by hand.

I think the fault is that the engine wasn't aligned correctly when the work was originally done and that's why it's knackered.

The set up is a standard beta engine with a PRM gearbox connected through a flexible coupling to the prop shaft. The prop shaft exits through a stern tube fitted with packing and lubricated by a standard greaser.

The boatyard deny any responsibility. They say it's a wear part and it's worn!!!!!!

I disagree and I am looking for some help.

Anyone interested??

 

Your prop may be off balance, As a matter of course when I take the boat out of the water for blacking, I

remove prop and take it in to be balanced (£40 last time). Just google prop repairs to find one near you.

With my system over 9000 hours have been logged under way with little wear to the shaft.

 

Firesprite

 

In the wild of the Fens

[mrsmelly]

2 years ago I had the prop shaft and stern tube renewed on my boat - I'm not even sure the replacement was needed in the first place, but the boatyard who did the work recommended it should be done. The assembly now needs to be replaced again even though the boat has only run for 968 hours since that repair.

The engine mounts are in good condition. The greaser, filled with the right grease, has been used before every trip and the stern tube flange has only ever been adjusted to a level where the prop shaft can still be turned easily by hand.

I think the fault is that the engine wasn't aligned correctly when the work was originally done and that's why it's knackered.

The set up is a standard beta engine with a PRM gearbox connected through a flexible coupling to the prop shaft. The prop shaft exits through a stern tube fitted with packing and lubricated by a standard greaser.

The boatyard deny any responsibility. They say it's a wear part and it's worn!!!!!!

I disagree and I am looking for some help.

Anyone interested??

 

Without seeing the instalation it is very hard if not impossible to diagnose but 1,000 hours is an atrocious lifespan for said equipment. As others have said many thousands of hours are usualy the case. I dont think the boatyard will do anything about it so I would go somewhere else and avoid where you had it done like the plague.

[nicknorman]

Could I hijack the thread to ask what is "the right grease" for a conventional stern gland?

Edited August 28, 2011 by nicknorman

[blodger]

Could I hijack the thread to ask what is "the right grease" for a conventional stern gland?

K99 Marine Grease; I have been admonished by my drydock for using ordinary grease. Grease designed for water applications apparently does a better job. Sometimes the tins look the same which is why ended up using ordinary Morris's

[nicknorman]

K99 Marine Grease; I have been admonished by my drydock for using ordinary grease. Grease designed for water applications apparently does a better job. Sometimes the tins look the same which is why ended up using ordinary Morris's

Thanks, i'd better check I bought the right stuff. Is it basically the water-resistant stuff used for pumps etc?

[nb Innisfree]

While in dry dock last week I had to pump the whole contents of the greaser before new stuff appeared at the prop end, so be generous with the greaser.

[AndrewBB]

The grease we use is Morris in a blue tin seems fine and says for marine use on the tin aswell.

[shaker]

Thanks for the comments so far.

It cost £500 to get the job done and will cost the same to get the repair completed.

The stupid thing is that if I take it to court it could cost me more, especially if I loose, so I need to build a solid case to make sure I win.

Does anyone work with a hire fleet? You may be able to give me some valuable information.

[mrsmelly]

Thanks for the comments so far.

It cost £500 to get the job done and will cost the same to get the repair completed.

The stupid thing is that if I take it to court it could cost me more, especially if I loose, so I need to build a solid case to make sure I win.

Does anyone work with a hire fleet? You may be able to give me some valuable information.

 

You are still on a sticky wicket. I worked in a hire fleet until recently and cans say that when the boats were sold off between 3 and 5 years old of persistent abuse they have never had any stern gear replaced and thats a lot of hours, but it still has no bearing on your application Im afraid. I would advis this time fitting a python drive as well the extra cost is worth it in many instances.

[Mike Jordan]

There is a section of the boatbuilding industry that delivers a crap job as standard, as already pointed out the sterngear should last for many thousands of hours if correctly installed. I dont think you have a realistic chance of winning in court since the conditions of use are not provable. The only person who will be sure of profiting will be the legal adviser! If the engine is sitting on flexible mounts of any kind there must be at least one flexible element and preferably two in the drive shaft. The best system in my opinion is to have a thrust bearing inboard of the stern tube, and drive through two universal joints and a spline on the prop shaft (just like an aquadrive or python drive) This system takes up more room but gets rid of all the allignment problems.

If you are forced to use a rigidly mounted engine and prop shaft again, I suggest that you check the allignment yourself when the boat is refloated. (some boats are a slighly different shape when floating rather than in the dock) You only need to slack off the bolts holding the grearbox/ drive half coupling and check the gap with feeler gauges, if its not within 1.5 thou it aint right!

Best of luck.

Mike

[shaker]

Mr Smelly,

Thanks for your response on the forum.

I am realy pissed off with the boat yard, especially their arrogent reply and I am fired up enough to give it a try in court. I'm hoping that if I put enough information in front of the court they will, "on the balance of probabilities", find in my favour. Along with other evidence I would like to show an example of boats used in a hire fleet, where they get thoroughly abused, running for many, many hours without stern gear replacement.

Would you be prepared to provide some information; what I am after is that X hire fleet had X number of boats with a drive system as I have described and that they ran for X number of hours (approx.) and X number required stern gear replacement in that time.

If you could do this for me that would be great.