#1
IP: 74.78.172.130
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loosing shaft out of coupler
It's creeping aft on its own and it's not good.
Launched last friday and now I think it will have to be pulled again. I installed a new MM Split Coupling this spring. It seemed to reassemble securely but it's halfway out and can't take much more. So any thoughts about this coupling and maybe ideas what I did wrong? Thanks in advance. Tim |
#2
IP: 107.0.6.242
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This happened to me once. Try to pull the shaft back to it's correct position. Remove the setscrews to be sure you are dead on the provided depressions and try to tighten again. Mark the shaft with a magic marker and watch it closely for a few weeks.
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#3
IP: 71.192.209.155
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If there is any danger of the shaft getting free put a zinc donut on the shaft on the inside to act as an emergency stopper.
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#4
IP: 24.224.206.117
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That's a good idea if there is room. Never really thought of it before but I guess that might keep it out of Davy Jone's Locker.
__________________
Mo "Odyssey" 1976 C&C 30 MKI The pessimist complains about the wind. The optimist expects it to change. The realist adjusts the sails. ...Sir William Arthur Ward. |
#5
IP: 216.115.121.240
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Brilliant! I even gave it a vote too
__________________
Whiskeyjack a '68 Columbia 36 rebuilt A-4 with 2:1 "Since when is napping doing nothing?" |
#6
IP: 199.29.247.15
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I do that on my boat not because I think the shaft will depart the boat - it probably won't - but because I don't want it ripping through my rudder at 2000 rpm as it attempts to.
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#7
IP: 71.118.13.238
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Collar it!!!
I was with a friend when he learned the hard way. He had just replaced the shaft housings and I straightened the shafts for him. When done we were launched from Cabrillo Boat Works in the LA Harbor. The boat was a 32' Chris woody with a fly bridge and a pair of Chevy 350's. We got her lit and across the harbor we started to test and head for Long Beach. The boat was running flawlessly and the shafts were very smooth. We settled in at around 3400 RPM's and cracked open a couple of beers to clelbrate when a lil boat cut across our bow abruptly, Bill trrottled back to the stops and a collision was avoided! However when he backed off we heard some horendous (the hatches were open) noises from the rear of the boat and water was running in fast through two holes, one from the empty shaft log 1 1/4" and the entire rudder through hull supports. When he throttled back the port shaft came loose and the spinning prop destroyed the rudder post et all. I got thigs plugged under water and he pluggved the log. Then we headed back to the yard as the cradle was still ready. Never found the shaft or prop and he had a very big bill when all was back in order.
Since then I have always commented when I see no retaining collar on a prop shaft!!! Dave Neptune4 |
#8
IP: 74.78.172.130
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I've put two zinc collars on the shaft so there's little chance it will fall out and be lost. That's good news.
Now what to do? It's clear there'll be a $400 charge to take a travel lift ride to and fro. I'm wondering if this can be fixed in the water. The install took pounding (lightly but firmly) to seat the shaft in the split coupling. The whole coupling is not split. The last part is compression. There's frighteningly little room between packing gland and coupler. It's like an inch or maybe two. The push has to come from the prop. All the packing has to come out to then spin the gland nut back down to increase the room to allow the key to placed in the shaft. I also don't know what went wrong. The shaft did not spin in the coupling. The key is in the slot. I guess the set screws clamping the whole thing tightly are not doing the job. There's only so much torque one can exert with a allen wrench. Any ideas? Tim |
#9
IP: 71.118.13.238
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Worth a try?$?
Tim, can't help much regarding the flange. However if you have room as I did in my boat, I shortened the hose on the box.
I also did an R&R to straighten the shaft and replace the entire stuffing box while in the water. I used a stub of plastic rod to pack the packing while working on the shaft. When I was ready to have the diver slide in the straightened shaft I slid off the old stuffing box and kept water to a minimum with a hand towel while he slid the shaft in gently and I held the new box in place. I was ready and had less than a gallon of water ingress in the two removals ie the shaft and then the box to slide in the new. Once the parts were in place and not adjusted or fastend yet there was just a bit of dripping I would hardly call a stream ~ no worries. I have done many shafts in this manner when I was doing a lot of straightening for hot boat and sailboat projects I was involved in. Dave Neptune |
#10
IP: 199.29.247.15
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A diver with a sledge could tap the shaft in from the water and might even have a little slide tool to make the job easier. I would definitely give this a try in an effort to save $400.
Something to consider, though, is the hole drilled in the end of the shaft for the cotter pin. It is possible to beat too hard on the end of the shaft and bend the little bit of metal between the aft end of that hole and the aft end of the prop. |
#11
IP: 74.78.172.130
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Thanks Dave and Tenders and others...
The shaft alignment was a challenge on land. The shorter MM key and my shaft are not matched. It all works but getting everything to slide in as one was hard. It took a bunch of attempts. Doing this with a sledge while underwater in 50deg cold sounds tough. I've reached out to Don M and to my truck hauler. I've proposed sitting on his trailer for an hour to do all this work. un pack gland, pull shaft, re seat key and install shaft, tighten, re pack gland. I don't know if he'll like it. I also do not know why I failed on the first attempt. Hopefully Don has some thoughs. Also, there are no through set screws to match up to a dimple in the shaft on these couplers. It's just the 4 screws on the side to clamp it down and key to hold in place. Tim |
#12
IP: 68.56.139.11
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It is hard for me to picture your situation. I juat want to say that taking out a shaft in the water is very easy. Well, as easy as it is on land.
If the shaft would usually just slide out with no interference, then the same will be true underwater. Like the other response, I have done this on a few boats. With my A 4, i have a 1 inch shaft. I just have a diver pull the shaft, and I follow it with a 1 inch dowel, with a little tape to make a taper, so it does not disappear. I have been the diver, and my wife did the inside work with no problem. I found that some people did not understand the concept, and thought that i was nuts. (that is still open to debate, but the shaft thing works) |
#13
IP: 24.34.54.47
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Quote:
It might make sense to be hauled out for $400 to effect this repair. -Jonathan |
#14
IP: 24.160.178.117
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I'm with Jonathan. I abandoned my plan to use a split coupler and stayed with a conventional 1-piece, but my plans for a split coupler included drilling and tapping for a retaining screw. Not sure why they don't come made that way.
__________________
Mark Smith 1977 c&c30 Mk1 hailing from Port Clinton, Ohio |
#15
IP: 96.229.195.76
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Protect the shaft!
Use a block of wood or a piece of poly to protect the shaft end when striking with an object like a rock or hammer!!
Dave neptune |
#16
IP: 206.125.176.5
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Hiker - I feel your pain. I hauled my boat in the spring for a week, painted the bottom & replaced the prop and happily relaunched, ready for a summer of big winds & big fun.
Immediately upon launching, I noticed a leak around the stuffing box..The motions related to the prop replacement had upset an old Marine Tex repair done to a failing shaft log by the P.O. The timing was good..much better than whacking a log or whale with the prop while sailing and breaking the fragile seal/repair! The boat did not sink, but this was obiviously something that had to be attended to, so I reluctantly scheduled (another) haul out within a week. It is only money, but IMO it is a LOT easier to do this type of work when you are safely on land. As I kept digging, I found big problems and was on the hard for I think about 8 weeks effecting repairs..however, the 'safety' of jackstands allowed me to take my time and do it all correctly & tackle a few other "well, while I am here, I might as well take care of x, y & z too." A more basic question: I cannot understand why your shaft (or the new coupler for that matter)would not have the means for a set screw? However, looking at the split coupling in the Moyer catalog, there appears to be only a set screw for the key. I guess the ability to clamp the coupler may in theory eliminate the need for a shaft set screw, but if it was me, I'd have one opposite the key..
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) Last edited by sastanley; 06-19-2012 at 09:31 AM. Reason: coupling comments |
#17
IP: 74.78.172.130
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Picture here
SO here's what I'm faced with. It seems the strong advice is to not pull the boat to do the repair. Don and I spoke this AM. He suggests doing the most to push the shaft back in after loosing all the screws and helping the coupler open a little more with a screw driver and hammer.
I'm not too confident this can be pushed back in without the aid of a diver. Tim |
#18
IP: 99.63.216.154
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Hiker
I replaced my coupling while the boat was in the water but I did need to get into the water to tap the shaft back in as far as it would go. I used a sort of plastic hammer and tapped it in gently while a buddy guided it into the groove. This did not get the shaft all the way in but it was lined up properly. A this point the shaft needed to go back in about another half inch so I left all the securing screws loose, started the motor in the slip, put it in forward gear and gave it the gas for awhile. Believe it or not this got the shaft all the way in. I tightened everything up and it has now worked flawlessy for several years. The water in my area is very warm during the summer so getting in is no big deal. I suppose if you are in an area with cold water as you said it may be a little more difficult and you may need a wet suit or hire a diver. You could probably find a guy in the area who cleans boat bottoms who would get in for a few minutes. DVD |
#19
IP: 24.152.131.155
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How well does the output coupling, rear seal and tailshaft tolerate hammering?
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#20
IP: 74.78.172.130
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Hammering sounds like a big word. The shaft was encouraged in the last 3/4" of the coupling with the aid of lubrication, wood block and a dead blow hammer. It was not explosive beating.
It seems the effort did not do lasting damage. Something had to be done. However, advice has been given that it should not be this hard. That maybe the casting was a bit undersized. My reality was it would not move in the last part and after all the time, effort and complexity of this whole job, it did not seem unreasonable to tap the shaft in and secure it. I found out tonight the shaft has moved about .5 inches. It is no where near coming out of the coupling. Movement at all is bad so it will be fixed. The split in the coupling allowed access to the shaft inside the coupling. I wish I had thought of that before getting into this issue. The zincs are not that far from the strut. Binding will happen if it goes much further. Tim |
#21
IP: 24.152.131.155
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Have there been dimples drilled into the shaft for coupler set screws to seat? I'm thinking not.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#22
IP: 74.78.172.130
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The single dimple on my shaft lines up with the split in the new coupling. There are no set screws in the coupling to line up with dimples real or imagined. This coupling has two set screws to hold the key in place. It can be seen in the catalog on this site.
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#23
IP: 24.152.131.155
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If it were mine I'd be adding two set screws 180 degrees apart and off the keyway with matching drilled dimples in the shaft.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#24
IP: 68.56.139.11
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I am not familiar with a split coupling. It looks like you can open it up, right?
I am thinking that any misalignment makes it want to back out of the coupling. How is the alignment? |
#25
IP: 166.147.72.16
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It looks to be
When I seen his picture that was the first thing I thought that it was misaligned. Hopefully the misalignment has not caused it to waller out the coupling.
__________________
With Powerboats, it's about the destination. With Sailboats, you are already there. Jeff S/V Karinya 1973 Grampian 30', Full Keel, A4 aux. |
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