Had a wonderful sail last weekend on my '79 H33 with a WSW wind at 10-15. Never tacked or jibed once the whole way from slip to anchorage, and the return trip was more of the same. Maintained a steady 6 knots on a close reach with the 150% genoa for the return trip. I started-up the old Yanmar 2QM15 upon furling-in the ginny and flaking the main and quickly realized there was no forward or reverse (no loud bangs either). I Immediately put out the genoa again and sailed safely back to the slip (though admittedly somewhat awkward arrival). A quick look in the engine compartment made the problem clear. The prop shaft backed-out of the coupling about 3 inches. Presumbably by the mere force of the water under the hull on the 3 hour close reach. I've now read up on this subject and heard the many stories of the coupler separating under power where it bolts together. However, not once have I heard of the shaft getting pulled out of the coupler, especially while under sail alone. I backed out the bolt that is supposed to lock the shaft in place and then dove into the crystal clear waters of baltimore's inner harbor to pound the shaft back into the coupling with the key inserted. I managed to get the shaft about an 1 & 3/4" into the coupler, but it's evident that it should go in further. Before reinserting I verified there were no obstructions on the interior of the coupler. Yet, no amount of pulling, prying, pushing or pounding would get it further in. I tried backing out the packing gland to lessen friction on the shaft, I even clamped a vice grip on the shaft (with fabric to prevent scratching). By 10pm I had enough and inserted the set-bolt again and fired her up. She moves well in forward and reverse with no apparent vibration (no more than usual). However, the shaft is still further back that it should be. Looks as though I'm going to have to interrupt the fun summer sailing with a haul-out and expensive fix. Question: Is there supposed to be one or two bolts tightened against the shaft in the outmost coupler (mine only has one)? Does anyone have any other thoughts to get the shaft back in place? As always, many thanks for the insights.
Propshaft decoupled on close reach
- Thread starter mjmulleriii
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Vent
MJ Assuming you cleaned the end of the shaft and the coupling well then you probably have an air lock in the coupling. You could tap the coupling at the very end with a very small hole or just wait until the pressure bleeds off and then try hammering the shaft in a little more. Try it again this weekend and you will probably gain a mm or so. Fair winds.
MJ Assuming you cleaned the end of the shaft and the coupling well then you probably have an air lock in the coupling. You could tap the coupling at the very end with a very small hole or just wait until the pressure bleeds off and then try hammering the shaft in a little more. Try it again this weekend and you will probably gain a mm or so. Fair winds.
Similar experience..
The lock bolts, my coupler has 2, would vibrate loose and the shaft would back out while in reverse. My remedy was first to run in forward, while tied to the dock, this pushed the shaft back in place. Then tighten the lock bolts, mine have small holes drilled in the heads, so I wired them down with monel wire. I've seen this on aircraft bolts and it prevents them from loosening again. Then I placed a hose clamp on the shaft about one-half inch clear of the packing gland nut. This will limit the travel should the shaft pull out again. How do you know that it is not fully seated already?
The lock bolts, my coupler has 2, would vibrate loose and the shaft would back out while in reverse. My remedy was first to run in forward, while tied to the dock, this pushed the shaft back in place. Then tighten the lock bolts, mine have small holes drilled in the heads, so I wired them down with monel wire. I've seen this on aircraft bolts and it prevents them from loosening again. Then I placed a hose clamp on the shaft about one-half inch clear of the packing gland nut. This will limit the travel should the shaft pull out again. How do you know that it is not fully seated already?
Hose Clamp
Great idea with the hose clamp. I certain can trust that this will happen again so that 2 cents of prevention is a must. I think the shaft should move further inside the coupler because I can see the wear marks from where it had previously rested for 20 years. As for the air lock I simply hadn't considered it. I did try to disassemble the coupler to place it first on the shaft and then reassemble with the 4 bolts, but after removing the bolts the adjoinging coupler pieces were stuck together. I honestly didn't give it much time or try to apply any anti-seize fluid. Perhaps I'll try again this weekend with more success. The most recent word from my local yard is that the boat must be hauled and shaft pulled to gaurantee proper coupler replacement. Something about small fractional margin of error is mandatory or "major" vibrations could occur. So my initial thought that a replacement coupler would be standard size was incorrect. I'm still going to try to use the existing coupler. To me, it's only a 15 horsepower engine and I'm comfortable with a larger margin of error. Anyone ever redrill one of the existing set-screw holes if it is obstructed?
Great idea with the hose clamp. I certain can trust that this will happen again so that 2 cents of prevention is a must. I think the shaft should move further inside the coupler because I can see the wear marks from where it had previously rested for 20 years. As for the air lock I simply hadn't considered it. I did try to disassemble the coupler to place it first on the shaft and then reassemble with the 4 bolts, but after removing the bolts the adjoinging coupler pieces were stuck together. I honestly didn't give it much time or try to apply any anti-seize fluid. Perhaps I'll try again this weekend with more success. The most recent word from my local yard is that the boat must be hauled and shaft pulled to gaurantee proper coupler replacement. Something about small fractional margin of error is mandatory or "major" vibrations could occur. So my initial thought that a replacement coupler would be standard size was incorrect. I'm still going to try to use the existing coupler. To me, it's only a 15 horsepower engine and I'm comfortable with a larger margin of error. Anyone ever redrill one of the existing set-screw holes if it is obstructed?
Check this
Properly installed there should be small shallow holes drilled in the shaft for the set screws to seat. If you remove the screws you should be able to see if the set screw holes are lined up with those in the shaft. If they are not (or were not before) the shaft will slip out during reverse thrust. I've had the set screws get loose from vibration on several vessels and now use "Lock tight" on them. As previously stated wire the screws in place. On some new installations that were very tight I put a bag of ice on the shaft and heated the coupling to improve clearance.
Properly installed there should be small shallow holes drilled in the shaft for the set screws to seat. If you remove the screws you should be able to see if the set screw holes are lined up with those in the shaft. If they are not (or were not before) the shaft will slip out during reverse thrust. I've had the set screws get loose from vibration on several vessels and now use "Lock tight" on them. As previously stated wire the screws in place. On some new installations that were very tight I put a bag of ice on the shaft and heated the coupling to improve clearance.
Hose Clamps?
I have heard the hose clamp hint before, but should the problem happen again, the hose clamp could rip apart the packing gland nut as it spins. As a remedy, I have heard of using a shaft zinc instead to eliminate the damage that a hose clamp could inflict.
I have heard the hose clamp hint before, but should the problem happen again, the hose clamp could rip apart the packing gland nut as it spins. As a remedy, I have heard of using a shaft zinc instead to eliminate the damage that a hose clamp could inflict.
In-the-water replacement
I had trouble with my coupler as well, but my problems were when it was new. I suppose over time anything could work loose. The things I've learned should still be usable. First, after installing the new one, I checked the bolts after an hour or so, then after a day or so, then after a week or so. (This was using the boat every day while cruising). I continued this until I was sure they didn't tighten any more. I used bolts made as set screws (pointed ends) with holes for safety wire. Use monel wire, such as you'd see for rigging, so that it won't corrode. Running a length of wire through both bolts won't be certain to keep the bolts there, but if they back out very much, they'll break the wire and it'll be obvious. Put some antisieze on the bolts in case you ever want to remove the prop shaft. To keep it from flying out if it does come loose, put your zinc on the propshaft close enough to the strut that it can't come out. (Say, 1/2" from the strut) This comes for free, since you'll have a zinc anyway. This will only help, though, if you keep replacing the zinc while there is still some left. You do not have to haul the boat to pull the shaft. Try this. Get the coupler loose from the transmission. Get the coupler off the shaft (using any of tricks that have been mentioned here before). Take a piece of tarp material about 18" square, wrap it over the end of the prop shaft and onto the stuffing box. Take a couple of hose clamps and clamp this to the back of the stuffing box. At this point you'll have a barrior to water coming in when you yank the prop shaft out from under the boat. It can leak some, but not enough to matter. Remove the strut bolts. If you've installed the bolts from above with arms welded to the heads so that they can only turn less than half a turn, as I've suggested here before, you can do it easily from underneath, and by yourself. I'd recommend tying a line to the shaft and strut before you do this so that if you drop it, you can get it back a lot easier. Yank out the strut and shaft. Put them on the dock. Go back under with a wooden plug, drive it in snuggly. Remove the tarp inside if you want to work on or replace the stuffing box, or just leave it. Do what you have to - have a machine shop get the fit right on the shaft, make a new whatever you need or whatever. Once your parts fit together correctly, do the reverse of the above. Use the haulout fees to buy the new coupler and stuffing box. Or to go to a nice supper. Or 3. Or cruise another week. I've left Rainbow Chaser sit this way for months while we searched the world for transmission parts. If you get into trouble, you can always do the haulout ro call a friend. Once you have it down, you'll be set to do repairs when the help isn't available - like in that remote anchorage you want to go to.
I had trouble with my coupler as well, but my problems were when it was new. I suppose over time anything could work loose. The things I've learned should still be usable. First, after installing the new one, I checked the bolts after an hour or so, then after a day or so, then after a week or so. (This was using the boat every day while cruising). I continued this until I was sure they didn't tighten any more. I used bolts made as set screws (pointed ends) with holes for safety wire. Use monel wire, such as you'd see for rigging, so that it won't corrode. Running a length of wire through both bolts won't be certain to keep the bolts there, but if they back out very much, they'll break the wire and it'll be obvious. Put some antisieze on the bolts in case you ever want to remove the prop shaft. To keep it from flying out if it does come loose, put your zinc on the propshaft close enough to the strut that it can't come out. (Say, 1/2" from the strut) This comes for free, since you'll have a zinc anyway. This will only help, though, if you keep replacing the zinc while there is still some left. You do not have to haul the boat to pull the shaft. Try this. Get the coupler loose from the transmission. Get the coupler off the shaft (using any of tricks that have been mentioned here before). Take a piece of tarp material about 18" square, wrap it over the end of the prop shaft and onto the stuffing box. Take a couple of hose clamps and clamp this to the back of the stuffing box. At this point you'll have a barrior to water coming in when you yank the prop shaft out from under the boat. It can leak some, but not enough to matter. Remove the strut bolts. If you've installed the bolts from above with arms welded to the heads so that they can only turn less than half a turn, as I've suggested here before, you can do it easily from underneath, and by yourself. I'd recommend tying a line to the shaft and strut before you do this so that if you drop it, you can get it back a lot easier. Yank out the strut and shaft. Put them on the dock. Go back under with a wooden plug, drive it in snuggly. Remove the tarp inside if you want to work on or replace the stuffing box, or just leave it. Do what you have to - have a machine shop get the fit right on the shaft, make a new whatever you need or whatever. Once your parts fit together correctly, do the reverse of the above. Use the haulout fees to buy the new coupler and stuffing box. Or to go to a nice supper. Or 3. Or cruise another week. I've left Rainbow Chaser sit this way for months while we searched the world for transmission parts. If you get into trouble, you can always do the haulout ro call a friend. Once you have it down, you'll be set to do repairs when the help isn't available - like in that remote anchorage you want to go to.
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