Propeller shaft pulled out!

[jwmurphy]

I've had a Bristol 27 with an A4 for 37 years and have not had any problems with the propeller shaft, until yesterday, when while being driven aground on a lee shore in 30 knot gusts the shaft apparently pulled out of the coupling leaving me without forward or reverse and alot of water filling the bilge. A local marine mechanic suggested that too much reverse could have caused the shaft to back out. Has anyone experienced a similar situation and what steps were taken to prevent it from happening again?

[romantic comedy]

You dont say what the condition of the shaft and coupling are.

I bought my tartan 16 years ago. On my first time out, my shaft came out of the coupling when I was backing into the slip. The coupling had worn the key way to twice the width. So I got a new coupling and all has been fine since then.

I would imagine that you just need to see what went wrong and repair it.

[ndutton]

You don't say what the condition of the shaft and coupling are.

For instance,

• Is the keyway intact?
• Were the setscrew(s) tight? I have doubts and wonder why not.
• Was the shaft dimpled where the setscrew(s) land?
• Were the setscrews wired?
• If yes, what kind of wire? Stainless?

It's interesting to consider the vital role those little setscrews play in the long term operation of our boats.

[CalebD]

Time for a new shaft?

I'm not expert but I did replace the original bronze shaft on my 44 year old Tartan 27' with A4 this past winter. Our old shaft was worn at the cutless bearing and needed replacing after 44 years of service.

If this is how your Bristol 27's hull looks: http://sailboatdata.com/viewrecord.asp?class_id=521
I'm not sure how a simple grounding could have messed with your prop, since it is in an aperture like mine.

In any case, your coupling separated from the engine despite the 3 bolts and wire that held it do the drive coupling. It sounds to me as though it is time to haul the boat, inspect and replace everything you can (including your rudder shaft).

The good news is that a new stainless steel shaft should only cost you a little more then $200 and you can probably just use a Sawzall to cut your 37 year old shaft in half to extract it from the boat without removing the prop, coupling or rudder beforehand. It is much easier to remove the prop and coupling from the shaft in a shop environment than in the bowels of your engine compartment and it only takes about 10 minutes to carefully cut the shaft with a Sawzall while squirming for access.

The bad news is that you should probably replace the cutless bearing, shaft log hose and probably even your coupling while you are doing this. There is also the remote possibility that your engine has become out of alignment and you may need to check or redo your engine mounts.

The mediocre news is that you should probably find a good prop shop near you to take your old shaft, prop and coupling to. They will need the prop and perhaps a new flange for getting a good fit with the shaft they fabricate for you.

[Al Schober]

Just tightening the setscrew against the shaft doesn't make it. Our club launch snagged a lobster pot and pulled the shaft out of the coupling - lucky it didn't pull the shaft out of the packing and sink the boat!
What's needed is a drill point in the shaft for the nose of the set screw to sit in. This gives the set screw some area to bear against, rather than just skidding along the surface of the shaft.

[jwmurphy]

You dont say what the condition of the shaft and coupling are.

I bought my tartan 16 years ago. On my first time out, my shaft came out of the coupling when I was backing into the slip. The coupling had worn the key way to twice the width. So I got a new coupling and all has been fine since then.

I would imagine that you just need to see what went wrong and repair it.

remantic commedy,
When I have to repack the stuffing box things are so tight I cannot back the packing nut far enough back from the stuffing box to insert new packing. Therefore, I have to remove the shaft in order to repack. I am on my third shaft, two previous ones were bronze (sometimes it was easier to cut and replace the shaft when I needed to repack) and the current shaft is stainless. The stainless shaft was originally installed in 2004 along with a reconditioned stuffing box, prop and cuttless bearing etc. In spring 2012 I pulled the stainless shaft in order to repack. At that time everything looked good including the coupling, keyway etc. It was still necessary to drive the shaft into the coupling with a mallet. I'm thinking that if somehow the keyway was lost the coupling and shaft could be spining at different revolutions which may have heated the coupling enough so that when I went into reverse the shaft "walked" out of the coupling?? I have not had the time to inspect the coupling, keyway and shaft up close after this incident yet, I hope to get to the boat yard this week.
jwmurphy

[jwmurphy]

For instance,

• Is the keyway intact?
• Were the setscrew(s) tight? I have doubts and wonder why not.
• Was the shaft dimpled where the setscrew(s) land?
• Were the setscrews wired?
• If yes, what kind of wire? Stainless?

It's interesting to consider the vital role those little setscrews play in the long term operation of our boats.

ndutton,
Regarding setscrews: I don't have any coupling to shaft set screws. The shaft is a "press" fit into the coupling. There is one "setscrew" in the coupling that holds the keyway in place. A stainless wire was used on this application and was replaced new in spring 2012 (see the following discussion). When I have to repack the stuffing box things are so tight I cannot back the packing nut far enough back from the stuffing box to insert new packing. Therefore, I have to remove the shaft in order to repack. I am on my third shaft, two previous ones were bronze (sometimes it was easier to cut and replace the shaft when I needed to repack) and the current shaft is stainless. The stainless shaft was originally installed in 2004 along with a reconditioned stuffing box, prop and cuttless bearing etc. In spring 2012 I pulled the stainless shaft in order to repack. At that time everything looked good including the coupling, keyway etc. It was still necessary to drive the shaft into the coupling with a mallet. I'm thinking that if somehow the keyway was lost the coupling and shaft could be spining at different revolutions which may have heated the coupling enough so that when I went into reverse the shaft "walked" out of the coupling?? I have not had the time to inspect the coupling, keyway and shaft up close after this incident yet, I hope to get to the boat yard this week.
jwmurphy

[jwmurphy]

I'm not expert but I did replace the original bronze shaft on my 44 year old Tartan 27' with A4 this past winter. Our old shaft was worn at the cutless bearing and needed replacing after 44 years of service.

If this is how your Bristol 27's hull looks: http://sailboatdata.com/viewrecord.asp?class_id=521
I'm not sure how a simple grounding could have messed with your prop, since it is in an aperture like mine.

In any case, your coupling separated from the engine despite the 3 bolts and wire that held it do the drive coupling. It sounds to me as though it is time to haul the boat, inspect and replace everything you can (including your rudder shaft).

The good news is that a new stainless steel shaft should only cost you a little more then $200 and you can probably just use a Sawzall to cut your 37 year old shaft in half to extract it from the boat without removing the prop, coupling or rudder beforehand. It is much easier to remove the prop and coupling from the shaft in a shop environment than in the bowels of your engine compartment and it only takes about 10 minutes to carefully cut the shaft with a Sawzall while squirming for access.

The bad news is that you should probably replace the cutless bearing, shaft log hose and probably even your coupling while you are doing this. There is also the remote possibility that your engine has become out of alignment and you may need to check or redo your engine mounts.

The mediocre news is that you should probably find a good prop shop near you to take your old shaft, prop and coupling to. They will need the prop and perhaps a new flange for getting a good fit with the shaft they fabricate for you.

CalebD,
Yes, that is essentially my Bristol 27, mine was built in 1975 and has a little different cabine line.

I agree, I don't think the grounding had anything to do with the shaft pulling out other than the fact I was using alot of reverse when I first touched bottom. I ended up listing about 45 degrees in a couple feet of water, but by then the water intake was out of the water and the engine secured.

Regarding the coupling, I have a direct drive and the coupling is still secured to the engine.

Yes, the boat a float and was pulled first thing the next morning.

Discussion FYI: Regarding setscrews: I don't have any coupling to shaft set screws. The shaft is a "press" fit into the coupling. There is one "setscrew" in the coupling that holds the keyway in place. A stainless wire was used on this application and was replaced new in spring 2012 ( see the following discussion). When I have to repack the stuffing box things are so tight I cannot back the packing nut far enough back from the stuffing box to insert new packing. Therefore, I have to remove the shaft in order to repack. I am on my third shaft, two previous ones were bronze (sometimes it was easier to cut and replace the shaft when I needed to repack) and the current shaft is stainless. The stainless shaft was originally installed in 2004 along with a reconditioned stuffing box, prop and cuttless bearing etc. In spring 2012 I pulled the stainless shaft in order to repack. At that time everything looked good including the coupling, keyway etc. It was still necessary to drive the shaft into the coupling with a mallet. I'm thinking that if somehow the keyway was lost the coupling and shaft could be spining at different revolutions which may have heated the coupling enough so that when I went into reverse the shaft "walked" out of the coupling?? I have not had the time to inspect the coupling, keyway and shaft up close after this incident yet, I hope to get to the boat yard this week.
jwmurphy

[jwmurphy]

Just tightening the setscrew against the shaft doesn't make it. Our club launch snagged a lobster pot and pulled the shaft out of the coupling - lucky it didn't pull the shaft out of the packing and sink the boat!
What's needed is a drill point in the shaft for the nose of the set screw to sit in. This gives the set screw some area to bear against, rather than just skidding along the surface of the shaft.

Al Schober,
In my case there wasn't any outside infulence such as a lobser pot, just reversing hard to get to deeper warter.
Regarding setscrews: I don't have any coupling to shaft set screws. The shaft is a "press" fit into the coupling. There is one "setscrew" in the coupling that holds the keyway in place. A stainless wire was used on this application and was replaced new in spring 2012 (see the following discussion).
When I have to repack the stuffing box things are so tight I cannot back the packing nut far enough back from the stuffing box to insert new packing. Therefore, I have to remove the shaft in order to repack. I am on my third shaft, two previous ones were bronze (sometimes it was easier to cut and replace the shaft when I needed to repack) and the current shaft is stainless. The stainless shaft was originally installed in 2004 along with a reconditioned stuffing box, prop and cuttless bearing etc. In spring 2012 I pulled the stainless shaft in order to repack. At that time everything looked good including the coupling, keyway etc. It was still necessary to drive the shaft into the coupling with a mallet. I'm thinking that if somehow the keyway was lost the coupling and shaft could be spining at different revolutions which may have heated the coupling enough so that when I went into reverse the shaft "walked" out of the coupling?? I have not had the time to inspect the coupling, keyway and shaft up close after this incident yet, I hope to get to the boat yard this week.
jwmurphy

[ndutton]

Take a look at this coupling

It has set screws off the keyway that land on the shaft itself. The common practice is to install the shaft, mark the position of the setscrews on the shaft, remove the shaft, drill substantial dimples into the shaft at those locations, reinstall the shaft being careful to align the dimples with the setscrew holes and land the setscrews into the dimples. Lock wire through the setscrew heads will keep it all secure.

I realize you are beating your shaft into place and the idea of installing, marking, removing, drilling and reinstalling the shaft is not appealing but neither is losing the shaft at the worst possible time as you just experienced. For this reason I am not a fan of the typical press fit between the shaft and coupler. Here's a description of my reasoning from a thread this past summer:

I've never been one to beat things into place. After getting caught up in the Motorcycle Mania series on the Discovery Channel featuring West Coast Choppers (local for me) and Jesse James' beautiful work I attempted to watch the American Chopper series featuring that dysfunctional Teutul family screaming at each other. More irritating than the screaming it seemed their principle tool was a dead blow hammer. They'd beat the forks into the trees or beat the axles into place. They couldn't even fit a chromed air cleaner without a love tap. Cut to form and beat to fit, that was their mantra.

So what's the point of all that? My aversion to beating things into place existed when I worked at the boat manufacturers. For the shaft to coupler fit - and here's where I'm confessing my sins - I'd dress the bronze shaft end with a file until the coupler slid on by hand. The only things holding the shaft in were the set screws in the shaft dimples and believe me, those dimples were generous.

So what's a proper fit? All the pro's attest to a fit so tight it has to be installed by John Henry. Removing it later is an adventure too. I remember Shawn's picture of his output flange after removing the shaft, totally destroyed. His shaft may as well have been welded in place. We've heard more than a few times the expedient solution to removal is to cut the shaft, more destruction. I've been guilty of recommending a Sawzall to those facing the dilemma. It solved the problem in short order but sacrificed an otherwise serviceable shaft in the process.

For me, I'd opt for the way I used to do it or a split coupler before beating the shaft into place where it's near impossible to remove in the future.

[Mo]

I will check my shaft.

Neil,
That's something I've not touched on mine. I think I'll have a look at it once the boat comes out. I'm thinking I'll remove one of the set screws and measure the depth to see if the shaft was drilled...peace of mind if nothing else.

[Al Schober]

Mentioned previously about a drill point in the shaft for the set screw(s).
Navy practice is to put a circumferential groove in the shaft forward of the coupling keyways. A two piece collar fits into this groove, and then the shaft coupling with the keyways fits behind it. Coupling bolts go through the whole mess. No way, no how, that shaft's coming out.

[CalebD]

Neils photo of a flange shows two set screws. Our old coupling which we re-used only had one set screw.
Hmmm!

[ndutton]

Caleb,

You can always drill and tap an additional hole in the coupler, they're mild steel. The setscrews are case hardened steel though, be sure to get one with the wire hole already drilled or you'll be hating life.

Close scrutiny of the couplings in the Moyer catalog shows the extra setscrew. You can barely see it on the left face and the picture also shows 2 setscrews.

[sastanley]

Caleb, I am pretty sure my new coupling only has one set screw, but I am sure my shaft has a dimple..

jwmurphy, it sounds like someone in spring 2012 must have made an error in the re-construction process of your shaft assembly.