Maintenance/problems with shaft drives.

[Murv]

Quick question.
I'm acutely aware of the problems that outdrives can cause. But what about shafts?
How much maintenance do they need and what sort of problems can you get?

My understanding (which is practically zero so please correct me) is that it's a compression joint between the dry bit and the wet stuff, packed with a stuffing that you fire a little grease into now and again to keep the wet stuff the preferred side of the boat.
Do the joints fail? Are there any major pitfalls to shaft drives?

I am aware of the advantages that outdrives can offer, but am just interested in any downsides to shafts (except the obvious that you can't just lift a shaft and inspect/clear your prop)

Thanks in advance,

Chris

EDIT: I should point out my question is really relating to shafts on old boats. I'm sure both systems are absolutely fine when brand new, but things seem to go downhill after a few Years of bobbing about in seawater!

 

[Nick_H]

I have Tides dripless seals and have never touched them in 7 years of ownership, on a boat now 10 years old.

 

[DAW]

I also have good experience of Tides dripless seals. The boat is now 9 years old with 600 hours of summer use in the Med and although there were no specific problems or leaks, the seals were replaced this year as part of routine preventative maintenance during the annual lift.

 

[Hurricane]

At risk of tempting fate, our dripless seals have never been a problem either.

Our old Sealine had good old fashioned glands that you have to pack.
They only weeped a little once so rather that just tightening them, I waited until the next lift and had them professionally repacked.
It turned out that just "nipping them up" would have fixed the weeping.
There is nothing wrong with the older (packable) shaft seals - in fact you know exactly where you are with them.

IMO, shafts are far easier to maintain than outdrives.
However, you have to think very carefully when you are in shallow water
Outdrives can be lifted but just touch the bottom with shafts and you could bend one out of alignment.
Then you will get problems - I believe that realigning can be a nightmare.

As a shaft boat gets older, you may also need to change the Cutless bearings which can be another nightmare.
But if you are buying a shaft boat check that there is no "play" in the bearings and they should last.

Hope that helps

 

[gordmac]

The stern gland may need re packing eventually and a bit of greasing and/or adjustment now and again. The Cutless bearings need replacing when they wear, probably years of life though. The packing in the stern gland may wear the shaft eventually too.

 

[Murv]

That's extremely helpful, thanks all.


Couple more quickies if I may.
Worst case scenario and both cutlass bearings wore out/needed replacing, could they be replaced with a modern dripless system and what would be a very rough ballpark sort of cost? Or, if not, to replace the cutlass bearings?

Sorry for the really vague questions, just trying to get some very rough ideas.
For example, if I hit the bottom on my outdrive, it costs around £1500.00 and 3 Months to rectify, just trying to ascertain whether that sort of problem would be completely avoided with shafts.

So, with a deep keel that protected the props from grounding, and assuming no play in the bearings, it would be reasonable to expect a boat with twin screws on shafts to last the Year between lift outs with a minimum (possibly none) of maintenance?

 

[Murv]

The stern gland may need re packing eventually and a bit of greasing and/or adjustment now and again. The Cutless bearings need replacing when they wear, probably years of life though. The packing in the stern gland may wear the shaft eventually too.

Is that the sort of thing that would be covered by survey? So, if the bearings are good, shafts aren't worn, it would, again, last the Year between lifts?

 

[Nick_H]

Is that the sort of thing that would be covered by survey? So, if the bearings are good, shafts aren't worn, it would, again, last the Year between lifts?

They will wear more quickly in muddy/silty water, but should still last a number of years without attention.

WRT to your earlier question, and as Hurricane pointed out, you really dont want to hit the bottom with shafts, even more so than with outdrives.

 

[Murv]

They will wear more quickly in muddy/silty water, but should still last a number of years without attention.

WRT to your earlier question, and as Hurricane pointed out, you really dont want to hit the bottom with shafts, even more so than with outdrives.

Superb, thank you
So, could hitting something in the water (large semi-floating log or similar) cause major issues with a shaft?

 

[blueglass]

So, with a deep keel that protected the props from grounding, and assuming no play in the bearings, it would be reasonable to expect a boat with twin screws on shafts to last the Year between lift outs with a minimum (possibly none) of maintenance?

Unless you are very unlucky - absolutely yes. in my experience we went for 5 years on an 8 year old boat (and many many miles) before any attention required.

 

[Hurricane]

Worst case scenario and both cutlass bearings wore out/needed replacing, could they be replaced with a modern dripless system and what would be a very rough ballpark sort of cost? Or, if not, to replace the cutlass bearings?

IMO, not necessary to replace the system - just fix/maintain it.
There is absolutely nothing wrong with the older seals - in fact they would me much easier to fix if something went wrong.

Dripless seals require a smooth finish round the shaft
Spare dirpless seals are usually fitted on the shaft in the engine room in case of problems

And as far as the Cutless bearings are concerned, if they need replacing, they have to be done - ask the surveyor for advice.
And remember there may be two Cutless bearings on each shaft - one in the P bracket and one in the hull.

 

[Murv]

Fantastic, thanks very much, invaluable stuff

It always seems that shafts are the perfect system, but having never had shafts, just wanted to be aware of what possible pitfalls there could actually be.

Thanks all, it's greatly appreciated.

 

[Nick_H]

Superb, thank you
So, could hitting something in the water (large semi-floating log or similar) cause major issues with a shaft?

Well yes, it's possible, but you could also be hit by lightening or boarded by pirates. It's a small risk, and one that most boat owners are happy to take, and also not good enough reason in itself to avoid a shaft driven boat imo. If it was a big concern then a keel, as you've mentioned, would reduce the risk from tiny to negligible.

 

[Murv]

Well yes, it's possible, but you could also be hit by lightening or boarded by pirates. It's a small risk, and one that most boat owners are happy to take, and also not good enough reason in itself to avoid a shaft driven boat imo. If it was a big concern then a keel, as you've mentioned, would reduce the risk from tiny to negligible.

Don't get me wrong, I appreciate what you're saying. But the choice at the moment is shaft drive, or no boat at all! I'm certainly not considering any other drive options.
Just trying to ascertain that the chances of problems are small enough (assuming enough care taken in choosing the right boat) that we should be able to run for a Year without drive problems.

 

[benjenbav]

Don't get me wrong, I appreciate what you're saying. But the choice at the moment is shaft drive, or no boat at all! I'm certainly not considering any other drive options.
Just trying to ascertain that the chances of problems are small enough (assuming enough care taken in choosing the right boat) that we should be able to run for a Year without drive problems.

Couple of other factors to think about: shafts take up more space. A sterndrive unit can be shoved pretty much to the blunt end. Not so with shafts. Also shafts tend to be less economical.

Lots of advantages also, of course.

 

[Spi D]

You'd normally see a completely different weight distribution with shafts. Engines placed near the boat centre really helps balance, a benefit when it gets rough.

Several boats are designed so that the props will never hit the bottom.

Technically shafts are so much simpler than sterndrives, whose purpose is to connect a static engine to a trim/tilt/turn -able prop.

As a fellow boater puts it: If shafts are good enough for Maersk, they're good enough for me too.

 

[Flynnbarr]

IMHO Murv,you have been extremely unlucky with all your issues,one after another.most people run yr after yr without any of the problems you have encountered,shafts or drives.
You pay the surveyor,you can ask him to concentrate on things you are unsure/concerned about.
Take a more experienced boater with you when you find something you like,old git maybe I'm sure he can sniff out a wrong 'un,proof of maintenance etc being a good start.

 

[hartcjhart]

Don't get me wrong, I appreciate what you're saying. But the choice at the moment is shaft drive, or no boat at all! I'm certainly not considering any other drive options.
Just trying to ascertain that the chances of problems are small enough (assuming enough care taken in choosing the right boat) that we should be able to run for a Year without drive problems.

does that mean Dave could not help

 

[superheat6k]

I recently had to replace both cutlass bearings on my Port shaft recently and as a precaution replaced the PSS seal at the same time, as these I understand have a life expectancy of around 7 years, and should one leak after this time then Insurers could have an excuse not to pay a claim due to failure to properly maintain the boat, although I have no specific knowledge of incidents to state this as fact. My PSS was likely around 12 years old.

Considered using a so called excellent Tides seal, but I will never know - as they could not be bothered to respond to my request for pricing I didn't bother to buy one, and won't bother buying one this Winter either when I tackle the stbd shaft. Aquafax came up trumps within minutes of my enquiry.

Pricing - PSS Seal for 1 7/8" shaft, which IMHO are excellent, £314; 1 1/2 cutlass bearings (one is a full bearing sawn in half with the end face turned true and will be used for the stbd upper later this year) £105; incidental parts approx £50. ~ £470 all up.

BUT on my Turbo 36 changing the seal and cutlass bearings is the Devil's work. I reckon such a job done professionally wouldn't have seen much change from at least £2,000 per shaft.

My Port outer cutlass had failed and had swollen so that it gripped the shaft so tightly I could barely turn the shaft by hand. Once removed the perished rubber simply peeled away from both cutlasses, which I reckon means the stbd are not too far behind in terms of degradation.

 

[Murv]

Thanks all, very useful stuff

IMHO Murv,you have been extremely unlucky with all your issues,one after another.most people run yr after yr without any of the problems you have encountered,shafts or drives.
You pay the surveyor,you can ask him to concentrate on things you are unsure/concerned about.
Take a more experienced boater with you when you find something you like,old git maybe I'm sure he can sniff out a wrong 'un,proof of maintenance etc being a good start.

We do seem to have been a tad unlucky, and do now have a boat expert on hand who is willing to come and look at any potential new purchases If we can buy something that just breaks down every other trip, it will be a 100% improvement so the bar isn't set particularly high!
I think that a pair of large, low revving, normally aspirated diesels, a semi displacement hull and not an outdrive in sight will go a long way to making sure we get to spend a little more time out on the water!

does that mean Dave could not help

Our boat was lifted out this afternoon, it's not going into the yard until tomorrow so it will be a couple of days until I can get back down to see what work is needed.
Once fixed, anti fouled and polished, she's up for sale.
I'm not getting another boat unless it's suitable and on shafts, hence the comment about shafts or nothing!