Shaft Imbalance

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My Sadler 32 wears out cutless bearings every season despite minimal usage.

I have to suspect a bent shaft or badly out of balance prop. How can I check this in Marmaris, Turkey?

Anyone know how to get a shaft or prop dynamically balanced out here?

Or advice on the same problem elsewhere?
 
The shaft is easily checked. Remove shaft from boat take off prop and clean shaft thoroughly. Take to a local bar and place on a pool table and roll it around. You will see if bent. The prop I am unsure of how to do other than sending awy toa specialist.

I have a 34 and replaced my stern gear last year I can't believe how smooth it is now.
The alignment if out shouldn't wear a cutless bearing out ina season unless you motor quite alot, but check and re-align.
 
Check shaft as suggested and you can do a static balance test of the prop.
I'm not sure how good this will be but it is a method I've used for wheels. Very simply you balance the prop/wheel on a point or small surface at the centre. So you need to make up a flat plate marked at its centre that the prop can sit on, balance it and it should sit there.

I'd glue a plate with a small dimple at the centre and use an upturned centre punch.

The bearing wear is more likely to be a P bracket out of alignement, I'm not sure if this boat has a forward bearing as well?

DIY checking of carrier alignment can be done with a new bearing that is machined to a clearance fit in the carrier (better with a hard bearing rather than a rubber one) With the shaft chocked you should be able to slide and turn the bearing in the carrier on the shaft. When this is achieved epoxy the bearing in place and leave to set.

Rapid wear could also be down to churned up sand particles, but I guess that is unlikely with th elow power and high prop you have on a Sadler.
 
Engine Alignment

alahol2 said:
Another possible cause of wear on the cutless bearing is an engine that is not lined up correctly. This is far easier to check than the balance of the prop/shaft. Worth checking.
Click to expand...

Same symptoms and wear, dealer said that alignment was correct last year when I bought her. Checked alignment on lifting last week, these are the before and after photos. Although the angles aren't great they give the idea. Didn't take very long to adjust the engine mounts, just hope that everything will be OK when she goes back in. Dealer has agreed to pay for new cutlass bearing!!!
 
I experienced quite rapid cutless bearing wear that turned out to be mostly due to wear of the shaft in way of the bearing. Presumably this leads to some impact in the contact, rather than pure sliding. The shaft was perfectly true as measured with a clock. Although the shaft wear didn't seem excessive, replacing it has made a big difference to bearing wear and to vibration.
 
I have twice had probems with new PRM G/B output flanges. Everything lined up on the spot, but shaft running out. After a lot of head scratching found that the female register in the flange was running out of true, so carefully checking the faces was doing no good. The first time I found this PRM replaced the coupling free. Next time they insisted that within 10 thou was the norm. Not norm enough for me, took it to Metal Surgery in Penryn, where they agreed that 10 thou was a rough cut, and bushed and rectified the coupling. Excellent people.

To discover this misalignment with the shaft/coupling in the boat I used a very long lever, in my case a 2ft screwdriver. Make a fulcrum very close to the shaft, within 2 or 3 in, and run the engine slowly in gear. Rest the end of the lever on the side of the shaft, (in my case in the register in the coupling) and against the fulcrum. The slight movement is magnified many times at the outer end of the lever. You can even measure and calculate it.

Of course a DTI is the best answer.
 
The photo above shows a shaft centered in the bearing carrier but the shaft will have some sag, ss shafts will bend under their own weight. If there is a forward bearing by moving the engine around you could be using this bearing as a pivot which will also mean it is unlikely that this bearing will end up being aligned with the shaft.

Our view (admitedly on larger boats mostly and hence bigger problems) is to set up a dry run with shaft supported to check shaft/bearing alignment, instal shaft and then adjust engine to the coupling. If you have elastomeric bearings you may also need to allow for sag in the bearing material especially at warmer temperatures.
 
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I seem to have to replace mine every two years so not as bad as yours. But I reckon this is down to lack of (or rather intermittent) use. I usually find a load of calcification on the shaft that seems to trash the rubber.
Hauled out this year and I reckon there's around 1mm play after two years in the water. So not bad but apparently they shouldn't wear at all in use.
 
I had a similar problem, and solved it with a Halyard Aquadrive unit - it just took up all the misalignement and vibration issues I had, and I've never had any more problems since.
 
How do you lined up engine correctly? Is there any special tools?
My Volvo 2002 on Vancouver 27 is a bit loud, can I adjust it myself....
 
Lining up is straightforward - although poor access can make it tedious. Split the gearbox coupling from the shaft, push the shaft back a bit and measure the gap betwenn the two faces. It should be the same all the way round. Turn the shaft through 90 degrees and repeat, then 90 degrees again until you have measured at 4 positions. If the gaps are not consistent you can adjust the engine mounts up or down until it is even, then bolt back up.

You should also check that the engine mountings are still sound and secure. On an old boat these could have collapsed or the locking nuts come loose.

A Bullflex will cope with 2 degrees misalignment, but it is not a cure for poor alignment of worn mounts. It is best when the boat has a shaft with a bearing either end of the stern tube and the engine is flexibly mounted.
 
I'm new to this alignment business myself. I now have my first boat with inboard engine, shaft, cutless bearing & folding prop, salied for 1 season so far with no vibration..

I'm puzzled as to why the marine industry doesn't use or adapt a drive shaft from a front wheel drive car.

Even a basic system from a mk 1 mini (u-bolts, rubber doughnuts & cv joint) would surely cure any minor misalignment and vibration problems? I realise that there are thrust issues but surely that could be solved by a simple thrust bearing arrangement on the inboard end of the prop shaft, before the connection with the CV joint end of the drive shaft.

Is this all too complicated or am I missing something here???
 
You have just described an Aquadrive, which some people use.

However there is really no need for all that complication as a properly aligned shaft, flexible coupling and good flexible mounts gives adequate refinement. Much of this can be avoided anyway these days by choosing a boat with a Saildrive - but thats another topic!
 
Thrust

surekandoo said:
I'm new to this alignment business myself. I now have my first boat with inboard engine, shaft, cutless bearing & folding prop, salied for 1 season so far with no vibration..

I'm puzzled as to why the marine industry doesn't use or adapt a drive shaft from a front wheel drive car.

Even a basic system from a mk 1 mini (u-bolts, rubber doughnuts & cv joint) would surely cure any minor misalignment and vibration problems? I realise that there are thrust issues but surely that could be solved by a simple thrust bearing arrangement on the inboard end of the prop shaft, before the connection with the CV joint end of the drive shaft.

Is this all too complicated or am I missing something here???
Click to expand...

What is different is that the cv joint on a car is not designed to take end thrust loads on the shaft, the wheel is only allowed to move in an arc, cornering forces are supported by a wishbone or swing arm. On a boat you are pushing the boat along with the end thrust on the shaft. This end thrust can induce shaft flex between bearings, it will also move the engine and spoil your accurate alignment. Aqua drive answers some of these issues but does not answer the shaft flex issue between stern tube bearing and P bracket bearing. Seatorque answers these problems by running the shaft in a fixed tube with internal bearings and a thrust bearing at the through hull.

But before you even start looking at your shaft alignment to engine coupling you should ensure the bearing/bearing carriers are true first. The shaft needs to be supported with bearings that are in a straight line to resist the tendency for the shaft to spiral and whip when thrust is applied with torque.
 
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