Hunter 41DS prop shaft to gearbox key way falling out

[16volt]

Hello - first time poster, first time owner (long term charter boat dog).

After bare boat chartering around the world and a couple of years of fractional ownership of a Hunter 380 we have bought our first boat, an 06 41DS. While we are learning the systems of this particular boat I was doing an inspection on the exhaust hose which needs replacement. Unfortunately, in doing so I saw this:

PXL_20260525_183239181 by Shannon, on Flickr

I am an experienced auto mechanic and this screams "holy crap" to me. The key was so loose I could push it half way back in with my finger. While the grooves in the shaft and salt build up (needs a stuffing box service) were noted in the survey, any shaft key issue was not and that tells me this is a recent development (we have only left the slip once since getting the boat home).

So my question is relatively simple, how boned are we? I would assume this is a tow to a haulout and have the shaft removed, inspected and machined/replaced? I welcome any and all feedback/help to understand more. Thank you.

 

[dlochner]

Before hauling the boat, try removing the coupling and reseating the shaft in the coupling. It may be necessary to spread the halves of the coupling to get the shaft further into the coupling. Then check the alignment. If the shaft can't be tightened in the coupling, try a new coupling. New couplings from Buck-Algonquin can be purchased on line for around $150. This can be done in the water, some water will enter, but nothing the bilge pump can't handle.

In the long run, the scoring on the shaft is a concern and certainly warrants a closer inspection. It may be prudent to replace the shaft. While you have things apart on the hard, replace the seal in the dripless seal. There should be instructions on the Lasdrop.com website. Oh, and then there is the cutless bearing...

 

[jssailem]

Manual turning of the coupler, does it slip on the shaft?

Certainly, a tow would be the safest action. When you did a sea trial, were any noises identified (squealing metal as the engine was turning the shaft?

I would want to inspect the shaft. That would entail a haul and shaft removal. While doing that, I would inspect everything from the transmission to the prop.

In Everett, we have the Prop Shop out near the Boeing Plant. They do excellent work. I had them mill a new shaft, fit my prop to the shaft, then fit and face a new coupler for the shaft. Got it back in 5 days.
Website

 

[Stu Jackson]

Putting aside the shaft scoring issue and dealing ONLY with the key:

I actually found NO key once!!! I went and got another one, pushed it in by hand, tapped it lightly and wrapped a zip tie onto it.
Years later the zip tie fell off.

They key is still there.

 

[Allan12210]

If you can tap it back in flush then install a stainless steel split collar on the shaft. Available from Amazon in the correct diameter. That will keep it in place.

 

[kosrae]

Is there a set screw missing? I am used to a split coupling with at least one set screw. To me it looks like the shaft is working it's self out of the coupling.

 

[dlochner]

Is there a set screw missing? I am used to a split coupling with at least one set screw. To me it looks like the shaft is working it's self out of the coupling.
View attachment 237938

Good catch, it should be visible poking out of the side of the coupling and there should be a safety wire securing the screw.

 

[16volt]

Thank you all for the responses. Being a car person I wasn't sure if that key was taking all the torque from the gearbox or not. If you look at the coupler the bolt heads look like someone has cranked on it before.

I have not tried to spin the shaft and watch the coupler. I assume the reason for the key is to secure it in position on the coupler. If the coupler keyway it's wrecked I would assume that the key is doing nothing but machining the coupler, does that make sense?

As far as loosening the coupler and trying to resecure, wouldn't the shaft and support strut bearings prevent pulling the shaft from the coupler? The coupler can't be the only thing securing the shaft into the boat.

 

[16volt]

Good catch, it should be visible poking out of the side of the coupling and there should be a safety wire securing the screw.

Good point, I'm going to look for a set screw next weekend. That being said, isn't a set screw a kewway essentially be the same thing?

 

[16volt]

If you can tap it back in flush then install a stainless steel split collar on the shaft. Available from Amazon in the correct diameter. That will keep it in place.

I really want to avoid mushrooming the key into place, especially if its not in the keyway of the coupler.

 

[16volt]

Manual turning of the coupler, does it slip on the shaft?

Certainly, a tow would be the safest action. When you did a sea trial, were any noises identified (squealing metal as the engine was turning the shaft?

I would want to inspect the shaft. That would entail a haul and shaft removal. While doing that, I would inspect everything from the transmission to the prop.

In Everett, we have the Prop Shop out near the Boeing Plant. They do excellent work. I had them mill a new shaft, fit my prop to the shaft, then fit and face a new coupler for the shaft. Got it back in 5 days.
Website

Thanks, we are up north in Semiahmoo. Appreciate the referral. My gut is pull it out of the water and inspect the shaft. I don't like unknowns. But it means a tow all the way to Bellingham.

 

[Davidasailor26]

As far as loosening the coupler and trying to resecure, wouldn't the shaft and support strut bearings prevent pulling the shaft from the coupler? The coupler can't be the only thing securing the shaft into the boat.

The cutless bearing and shaft seal will provide a little resistance, but definitely not enough to keep you from sliding the shaft back out of the coupling. Depending on the design of the boat the prop might hit the rudder before it can fall out of the boat entirely.

 

[dlochner]

I really want to avoid mushrooming the key into place, especially if its not in the keyway of the coupler.

The shaft is held in place in the coupling by three fthings, by friction from the tight fit, the key and key way, and the set screw.

The set screw is a hardened steel bolt with a hole drilled through the head for the seizing wire. There should be a dimple drilled into the shaft for the set screw.

At this point the coupling should be removed from the shaft and transmission, inspected and reinstalled aligning the dimple and keyway and everything aligned and tightened. Once it is back together, you can motor or sail to the yard for a haul out. To ensure the shaft doesn't fall out, install a shaft zinc between the coupling and the stuffing box and the shaft seal. This will prevent the shaft from falling out of the boat. A couple of properly sized hose clamps would also work

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[dlochner]

This afternoon I installed a new prop shaft and took a few photos of the coupler before it was installed on the shaft after they had been fit and faced.

This is the dimple for the set screw. It is opposite the key way.

This is the set screw. It is not yet fully engaged. Note the hole in the bolt head for the safety wire.

This is the coupler as it came back from the machine shop. It is not quite fully seated. The end of the key and end of the shaft should be flush with the coupling. This will put the dimple in the correct location. When it was installed it was very easy to fully seat the coupling on the shaft, one a few taps with a rubber mallet. The split coupling makes a world of difference when it comes to installing or removing the coupling.

 

[16volt]

Awesome, thank you for the pictures and description.

Headed to the boat this weekend and may tackle loosening the split coupled, checking the set screw and reseating the shaft. Does anyone have the torque spec for the coupler bolts?

 

[dlochner]

Headed to the boat this weekend and may tackle loosening the split coupled, checking the set screw and reseating the shaft. Does anyone have the torque spec for the coupler bolts?

As tight as you can get them!

 

[16volt]

As tight as you can get them!

LOL - As evidenced by the bolt heads in there. I plan on replacing those, anyone have the size and pitch on them?

 

[dmax]

Awesome, thank you for the pictures and description.

Headed to the boat this weekend and may tackle loosening the split coupled, checking the set screw and reseating the shaft. Does anyone have the torque spec for the coupler bolts?

Buck Algonquin said 18 lbs for the pinch bolts.