Prop shaft alignment

[Ron-Anne]

We recently purchased a 1990 Hunter 30 while she sat in the water and when we got her on the hard, we noticed the shaft strut was bent to the starboard, I plan on removing the strut and gettng it to a local machine shop for repairs and in the meantime I'm planning the re-install and can't see what alignment will be need except for the possible alignment of the engine to the shaft, am I missing something? it really looks like the strut gets installed onto the shaft, then fastened to the boat, check the coupling aligment and that's it, how far off am I?
Thanks
Ron

 

[Navicula]

note.....the boat must be back in the water (floating) to do the shaft alignment

 

[Ron-Anne]

Thanks, hadn't thought of that.
Ron

 

[Nodak7]

note.....the boat must be back in the water (floating) to do the shaft alignment

Navicula, had not heard that. Why would that make any difference?

 

[Nom De Guerre]

Navicula, had not heard that. Why would that make any difference?

The hull flexes differently when on the water as compared to on the hard. The alignment will change between the two.

 

[Marc Bergmueller]

The hull flexes differently when on the water as compared to on the hard. The alignment will change between the two.

+100

 

[TDudley]

I had to have my strut aligned a couple years ago. I thought they would move the strut. In stead they moved my shaft log. My strut was not bent, only misaligned with the tube that the shaft goes into. My mechanic maybe thought this was easier than trying to shift the strut

Two engine alignments will be needed. One out the water and one after the boat has Been in the water a week or two. That it for sure.

I can tell you that a complete engine alignment will be needed. I don't think just attaching the strut on the shaft will be enough in less you laser correct everything without the shaft. And even then you may have to make small adjustments to the engine. It's not hard, just involved with multiple measurements.

The payback you will get for short cutting it will be vibrations. Maybe slight or horrible vibrations. But vibrations still the same.

 

[Nodak7]

I had to have my strut aligned a couple years ago. I thought they would move the strut. In stead they moved my shaft log. My strut was not bent, only misaligned with the tube that the shaft goes into. My mechanic maybe thought this was easier than trying to shift the strut

Two engine alignments will be needed. One out the water and one after the boat has Been in the water a week or two. That it for sure.

I can tell you that a complete engine alignment will be needed. I don't think just attaching the strut on the shaft will be enough in less you laser correct everything without the shaft. And even then you may have to make small adjustments to the engine. It's not hard, just involved with multiple measurements.

The payback you will get for short cutting it will be vibrations. Maybe slight or horrible vibrations. But vibrations still the same.

Will this be necessary for a seal replacement as well? Or just the strut. We have had a few sailors in our group change over to a dripless seal and none, that I can recall, have had to realign their shafts or experienced vibrations from misalignments after they had done so. As a matter of fact I am going to install one on our boat this spring. Am I missing something here?

 

[Navicula]

Navicula, had not heard that. Why would that make any difference?

the other posters have already given you the reasons........but please dont let anyone near your boat or your friends boats that does not agree, with this

enjoy

 

[Alan]

Not.only MUST the boat be in the water, it must have been there for at least two weeks while the hull is re-shaped. The hull will slightly deform on the hard and will need a little time to acquire the "correct" shape which will allow for proper shaft alignment. Attempting alignmant without a significant adjustment period would only require a second adjustment after the hull has settled into a 'normal' shape.

 

[anchorclanker]

Excepting the need for alignments on the water, which would need to be done regardless, have any boat builders used an elastic flex coupling like a lovejoy or rag joint type coupling used on high end cars etc.? There are others available as I show here, that will actually accept some minor misalignment without making direct mechanical contact, and which will not transfer vibration as readily.