Propeller shaft length Hunter 376, 380 or 386

[Hamish_s]

Hello fellow Hunterowners.

Does anyone know, or is able to measure the length of their prop shaft on their 376, 380 or 386? My shaft fell out of the coupling ... I will be having a new one made, but the boat is in the water, and I want to replace the shaft overnight (saves money over several weeks on the hard).

The Sailboat owners store says 50", but I am looking for a confirmation from an owner as it would be $1,000 if i get it wrong.

Thanks for the help.

Hamish

 

[jssailem]

My shaft fell out of the coupling...

it would be $1,000 if i get it wrong.

How long is the one you removed? If it is about 50" then you got a good number.
By fell out do you mean lost at sea?

It would only be a $1000 if you got it too short. If too long then you could always cut it down a bit.

 

[Hamish_s]

How long is the one you removed? If it is about 50" then you got a good number.

It would only be a $1000 if you got it too short. If too long then you could always cut it down a bit.

Unfortunately, it would be close to $2,500 to haul the boat out, pull the shaft, measure, and THEN order the new shaft, with a 2+ week delivery. So, I understand that the shaft length is standard on the 376/380/386, and so, am seeking someone who knows the precise length and can confirm the 50". Then I can haul-out, hang in a sling overnight, swap the system out, and I save $2,100.

So, looking for anyone who knows ...

Cheers!

 

[Hamish_s]

Also, given I would need to fit and face to the new coupling, I is "easy" enough to cut some of the shaft off if it is too long, but than it has to be re-keyed and fitted back to the coupling. Too many cycles with a machine shop to be cost effective.

 

[jssailem]

I can understand. I replaced the shaft on my boat last year. There was no one to compare with. We had to cut the shaft and take the pieces to a prop shop to get the work done. They were great. I purchased the shaft and the machine work from them.

You have posted this query before and have not received a response. That is why I asked. Perhaps there is a prop shop that can help in your area.

 

[Hamish_s]

I know!! I only posted last Friday on the "Large Boat" forum, so, I felt I ought to open it up.

The store on this site is excellent, and helpful, and sell a standard length shaft and matched coupling. The challenge for me in Canada, is that the total cost ends up near $2,100 with shipping, duties etc. I can have it made for half that here. So, while I'd like to support the store, the differential between a custom job and buying from the Sailboatowners store, just cannot be supported. Its not their fault.

 

[jssailem]

Totally understandable.

 

[marcham]

Just did this on a Mirage 35. We had specs which were close, but the shaft ended up having to go back to the machine shop, adjusted, threads recut, etc..... then when reinstalling the strut had to be adjusted to align the strut with the shaft log.

This is not an overnight in the slings operation....

 

[JamesG161]

You should never replace your shaft while in the water.

Jim...

 

[Hamish_s]

Just did this on a Mirage 35. We had specs which were close, but the shaft ended up having to go back to the machine shop, adjusted, threads recut, etc..... then when reinstalling the strut had to be adjusted to align the strut with the shaft log.

This is not an overnight in the slings operation....

A fear of mine, but Marchand, does all that make sense? In effect, the strut, holding the Cutlass bearing is like a gun sight or laser ... It points at the same target the whole time - hopefully the centre of the transmission coupling. How could it be so far off target that it needed to be replaced? Should not the engine yaw, height and level be adjusted to meet your original strut aim?

I can imagine a length problem easily, but not all those other misalignments.

Good luck!

 

[jssailem]

Good analogy.
Start at the shaft log. That is the fixed point in the construction.

Align the strut with the attahed cutlass bearing (attached to the on the outside of the boat and adjustable) through the center of the Shaft log.

That will put the shaft in the middle of the shaft log.

With that alignment now fixed, move inside the boat and align the transmission (which is attached to the engine sitting on adjustable mounts) with the shaft. You had the coupler "fitted and faced" to the prop shaft. This gives you the reference you need to align the transmission to the shaft by measuring the gap between the couplers.

Think your Gun site lazer analogy only the fixed point is not the gun site by the shaft log (barrel).

 

[marcham]

Correct. There's no point going through the bother and expense to replace the shaft, re-align the engine and not take a few hours to also re-align the strut. As the boat ages, things flex a little. The log is fixed. The strut is designed to be adjusted.

Without an aligned strut, you can have vibrations, will wear out the cutlass bearing faster and in the worst case scenario cause wear between the shaft and log. Engine alignment cannot correct for a misaligned log and strut.

The engine can be rough aligned on shore, but alignment should also be fine tuned in the water.

Also, don't forget to have the shaft coupler faced for the shaft. Some mechanics will also lightly lap the propeller to the shaft.

This is a a few days out of the water operation... shortcuts don't usually pay off on boats.

Out of curiosity, how did the OP loose the shaft ???

 

[Hamish_s]

This is a a few days out of the water operation... shortcuts don't usually pay off on boats.

Out of curiosity, how did the OP loose the shaft ???

Simply fell out - no pulling required. How? Boat was bought abandoned from a marina (2017) in an auction. The original owner's husband had passed away, and my guess is that he was the yachtsman. I had found a key in the aft cabin above the couplings, but assumed it was for the winter-stored steering wheel. Also, after a few years, also noted that the locking engine mounting bolts were all loosened off. I now assume that the shaft and coupling was giving original owner problems, they took it apart and left the key out, left the grub screws to hold it together. I only run the engine maybe 40 hours a year and so, somehow, the thing stayed together all that time. Replaced fixed prop last year with a feathering one, and my second guess is that the new improved prop efficiency was enough to complete the uncoupling task.

Absurd, and lucky the anode was in a position to stop the prop shaft from falling out of the boat.

And yes, I was going to try to go with the "good enough" school of repair to hold it until the winter haulout, but better sense hit me, and to be clear, there really is only one right way to do things ...

Still struggling to confirm the standard shaft length though.

 

[Hamish_s]

So, finally back with my new 50" shaft. This is the proper length for the 376, 380 and 386.

Fit and face mean that when installing, simple taps on the end of the shaft put it into the coupling.

Still a question about the alignment issues. Given the engine is on rubber mounts and that the engine moves/vibrates, the idea of working to achieve a 5 thou tolerance seems over the top. Yes, everyone does it, but I do not fully follow the logic. I watched an excellent Youtube on the alignment process that included measuring the angle of the shaft both sides of the strut and working to make sure that angle is maintained as the shaft couples to the engine. That process seems to contradict the alignment process as when there is a gap at the bottom of the coupling (say), you lift the back of the engine. BUT, the alternative is to lift the front of the engine. Which is it? Well, it should be whatever is required to keep that strut angle from prop to tranny. Doesn't that make sense? But, I have not seen both of those considerations in any instruction set.

If anyone has experience or thoughts, please, I am listening.

For the record, replacing the cutlass and the stuffing box with a dripless were both simple and clean, though the water tube for the PSS needs to be off-vertical to fit under the floorboard, say, 30 degrees off centre.

Happy sailing!

 

[jssailem]

When doing my engine alignment I found Steve’s ideas helpful.

The Ins and Outs of Engine and Shaft Alignment Part I | Steve D'Antonio Marine Consulting

I found if there is a gap on the coupling I can raise the back or I can lower the front. Sometimes it takes doing both.

 

[Ralph Johnstone]

Given the engine is on rubber mounts and that the engine moves/vibrates, the idea of working to achieve a 5 thou tolerance seems over the top. Yes, everyone does it, but I do not fully follow the logic.

Very early on, I discovered this write up on the internet. I know, internet, dicey. After studying it, it seemed to be quite logical. It's a slow read but describes exactly the causes of misalignment. Once you've have your prop shaft aligned, you will never have to repeat the alignment checks for a bent shaft and coupling 90 deg. fit to the shaft as long as you don't have an accident involving the prop and/or shaft.

 

[Hamish_s]

Thanks @jssailem and Ralph. Both articles did summarize the issues well, and in a fairly practical way, though jssailem's article is very rigorous.

I know that when I first installed the shaft, i followed the ideas in this video (

) to take on the notion of the stress of the weight of the shaft and how it has a natural bend. 14.2 degrees was my angle aft and fore of the strut. When I positioned the shaft in almost working position before I put on the coupling (5" of shaft behind the strut and 4' into the boat), the centre of the shaft was about 1/4" below the centre of the transmission bore centre. But, when one puts on the coupling, and starts to attempt to measure offsets, one puts the coupling in position, and that builds in the angle of dangle (!). (This youtube also looks at the angle issue). So, if one is serious about all this, the complex article submitted by Ralph needs to be followed. Although, in that article, the Figure 2 image (B), I am not confident the author actually captures this problem when the shaft bends into what measures as proper position.

And then, at the end of the day, I am 100% confident that most prop and shaft installers do not follow most of these precision tasks. And as for the natural weight-sourced bend from the strut to the coupling, that is constant regardless of rotational position. Now, if the shaft is spinning at say, 6,000 RPM, the metallurgical rate of bend may not have sufficient time to bend, and it becomes effectively straight ... however, if not accommodated while installing, one locks in the bend and long term, stress the shaft. My guess is that it does not make that much of a difference in practice for the recreational boater, particularly sailboats.

You have all been very helpful. Thanks again.

Hamish

 

[jssailem]

most prop and shaft installers do not follow most of these precision tasks

From the number of boats I have enjoyed being on and the frequency of seeing shaft wobble, feeling vibrations or watching the replacement of prop struts your statement is spot on. The care one gives to aligning the shaft and transmission plays out in the longevity of the strut and cutlass bearing.

Fortunately for many sailboat owners, the use of their "auxiliary power" is minimal (in and out of the marina). The lack of use stretches the wear out over many years. Enough to forget the techniques and procedures involved.

Now that you have accomplished this task, are you ready to try and do it with a V-Drive?
The shaft coupler is beneath the engine on the other side of the transmission. To accomplish the task one needs to get intimate with the transmission. Wrap your arms around her and snuggle up close to reach the coupler.

 

[Ralph Johnstone]

(5" of shaft behind the strut and 4' into the boat),

Is this the final position of the prop behind the strut ? The recommended max. gap of the prop, behind the strut is 1.5 X the diameter of the shaft.

 

[Hamish_s]

Jeez Jim (jssailem), that's a bugger. Kind of like the original VW Beetle wherein one had to pull the engine to change the spark plugs!

Yes Ralph, the actual lengths fore and aft of the strut of the shaft itself (sans prop) is about 5.5" aft + 4" for the strut + 1" inside the coupling leaves the remaining 39.5" (I said 4' - too fast typing and bad math). When the prop is installed - in this case a new EWOL feathering prop - about 4" of shaft is inside the EWOL, leaving, in my case, 1.5" between the prop and the strut. Thank you for making sure I was not screwing up.