Alignment of propeller shaft to engine

[SailFastTri]

Just make sure you're not sitting on top of the engine while you make adjustments. Don't ask!

[Oceanride007]

Ellis
Is your engine hard bolted or Pussy footed. ? If its hard bolted, is your shaft Firmly held in 2 bearings.
In which case seems .002" is feasible, if not 2 bearings but 1, how are you going to support the shaft accurately while the 360 Deg rotation occurs.

2nd point, you may be surprised to know that usually the output shaft of the trany is splined not solid like your electric motor. Not only that but the coupling is often cast iron which can wear out with misalignment it does that to save the trany spline.

Other problems with misalignment, include coupling bolt breakage, aft seal leakage, possible shaft breakage, wear of stern tube or strut bearing, vibration but not always.

I can give you a procedure, but not without further information, do you have a spacer between couplings, does your coupling have spigots.

[EllisElectric]

Originally Posted by Sailmonkey

The little boats we're working with on this forum all have (rare exceptions) flexible mounts. These things are not like the main propulsion engine on a ship that is aligned and set in chockfast hard to the beds.

That would definitely cause alignment problems on flexible mounts, why can't they be chockfast hard to the beds?

[EllisElectric]

Originally Posted by Oceanride007

Ellis
Is your engine hard bolted or Pussy footed. ? If its hard bolted, is your shaft Firmly held in 2 bearings.
In which case seems .002" is feasible, if not 2 bearings but 1, how are you going to support the shaft accurately while the 360 Deg rotation occurs.

2nd point, you may be surprised to know that usually the output shaft of the trany is splined not solid like your electric motor. Not only that but the coupling is often cast iron which can wear out with misalignment it does that to save the trany spline.

Other problems with misalignment, include coupling bolt breakage, aft seal leakage, possible shaft breakage, wear of stern tube or strut bearing, vibration but not always.

I can give you a procedure, but not without further information, do you have a spacer between couplings, does your coupling have spigots.

I'm deciding whether to go with sail drive or shaft drive, I rather do shaft drive to move motor move centered in the vessel for weight distribution purposes.

[EllisElectric]

Originally Posted by Oceanride007

2nd point, you may be surprised to know that usually the output shaft of the trany is splined not solid like your electric motor. Not only that but the coupling is often cast iron which can wear out with misalignment it does that to save the trany spline.

I email Yanmar Diesel to see if they could manufacture a keyed shaft extending from the tranny instead of being splined.

[Oceanride007]

These are my thoughts.
Would suggest shaftdrive as a less problematic, better resale.
Pussyfoot reduces undesirable noise that could not be eliminated any other way on some boats.
Results can be disappointing should soft mounts perish due to oil contamination, time or fatigue.
Solid mounts for reliability, but you got to realize alignment on the hard is different to in the water.

Would prefer solid bolted chockfast or resilent hardwood. In case I had to go change to soft mounts in future I'd use chockfast or equivalent as a spacer, remember a yacht should be designed for a rollover, will your chosen soft mounts do the task if the engine is upside down (perhaps not important for cat).

Coupling should have spacer with spigots to assist with alignment, I be curious what Mr Yanmar says about solid output shaft, I do think better to have a castiron coupling spline as a weaklink. (The engine that failed in this manner had a broken aft soft mount).

One bearing AFT of shaftseal is enough especially when using soft mounts.

In case it all goes horribly wrong I have seen one installation with a Stainless steel frame used as a foundation plate with a extension - used to take a thrust bearing, with a special coupling (Can't remember name) that made accurate alignment unnecessary.

[spottsvillle]

I see how moving the front of the engine in the direction of the largest reading would bring the motor into alignment if it is out at the top or bottom but whats the move if it is out on the side?

Originally Posted by Lepke

You loosen the coupler behind the transmission until you can insert a feeler gauge between the 2 coupler pieces. You measure all the way around and if you want a proper job, shoot for no more than 0.002" difference. More than that will cause premature bearing wear in the rear transmission bearing and the shaft bearing. It also will cause noise that can impact fishing. If you take the time to get a .002" difference, you'll be better than most of the boatyards I've seen. Many yards just get it close and put in a "flexable" spacer and call it good. A couple years later you have repairs they won't accept blame for causing.
To achieve alignment, the engine front moves in the direction of the largest reading. Some engines have adjustable mounts, but in most cases, you add or take out shims under the mounts. Sometimes shims are needed between the engine and the mounts. While making adjustments, slack the holding bolts to all the mounts. After tightening the mounts, recheck measurements. If you set on land you have to recheck in the water.

[coastalexplorer]

I am restoring a 1982 vintage yacht that I acquired on the dry-land storage.The person I bought it from was in the process of removing the inboard power system and returning to the as built condition of using a 9.9 Hp Honda...which we have. BTW...does anyone out there carry both?

I took interest in this thread because I have yet to build the engine beds out of wood and put the 2003 28 Hp Volvo Penta diesel in. the hull is cold moulded construction.

Since the stern tube had not been destroyed we changed the cutlass bearing at the outboard end. And discarded the drip-less gland inboard which was a very old PYI that the spring had rusted loosing function and undoubtedly would have leaked. So a new one has been purchased from PYI (and have a tube connected to attach to the engine exhaust riser)

The important point is that during this change it was noticed that the shalft had during the previous installation been rubbing against the bore of the stern tube in the 4 to 5 O clock position and had created a small scallop;.035

To remedy this I installed another cutlass bearing as a stave bearing. Taking note that several respondents mention centering the shaft in the stern tube does anyone see anything wrong with this course of action.

My thinking was that it is almost imposible to align anything accurately if it keeps wobbling around like a moving target?

[Cadence]

Originally Posted by coastalexplorer

I am restoring a 1982 vintage yacht that I acquired on the dry-land storage.The person I bought it from was in the process of removing the inboard power system and returning to the as built condition of using a 9.9 Hp Honda...which we have. BTW...does anyone out there carry both?

I took interest in this thread because I have yet to build the engine beds out of wood and put the 2003 28 Hp Volvo Penta diesel in. the hull is cold moulded construction.

Since the stern tube had not been destroyed we changed the cutlass bearing at the outboard end. And discarded the drip-less gland inboard which was a very old PYI that the spring had rusted loosing function and undoubtedly would have leaked. So a new one has been purchased from PYI (and have a tube connected to attach to the engine exhaust riser)

The important point is that during this change it was noticed that the shalft had during the previous installation been rubbing against the bore of the stern tube in the 4 to 5 O clock position and had created a small scallop;.035

To remedy this I installed another cutlass bearing as a stave bearing. Taking note that several respondents mention centering the shaft in the stern tube does anyone see anything wrong with this course of action.

My thinking was that it is almost imposible to align anything accurately if it keeps wobbling around like a moving target?

JMHO,

It sounds as though you have the situation under control.

Best of luck.

[4HMainer]

When she's out of the water check the alignment of the shaft bearing carriers, if you get bearings made for an epoxy fit (clearance) you can have a dry run assembly. With shaft chocked new bearings can slide into carriers and be turned easily if it's all straight. Many lightweight struts get moved over time.