View Full Version : Busted propeller shaft

09-04-2007, 10:04 AM
I'm new to posting to the Forum, but I've been reading alot on the board for a while. Had a very unusual thing happen to the boat over the Labor day weekend. The propeller shaft broke completedly in half, just in front of the main strut.
I was towing my daughter on the wakeboard when the boat started shuddering badly. I pulled the throttle back, thinking there may have been some trash on the prop, although I was in approx. 15 of water. I reversed the engine, still could feel the shudder, so I started to idle over to pick up my daughter, when it felt like I'd lost the prop totally. The engine was still running smoothly, just weren't going anywhere. I turned it off, jumped overboard, and much to my surprise, felt the prop up against the rudder. After sliding my hand up past the strut, I felt the end of the shaft, it was a very sharp break, almost like glass.

Luckily we had met our sister-in-law and her husband for a day of wakeboarding so we got them to tow us back to the ramp, which wasn't too far. Really hated those 'Mastercrap' comments I was getting (he had a Searay) After trailering the boat manually, I inspected the strut and found it to be bent to port slightly, the two parts of the shaft when placed back together don't quite line up, maybe approx. 3/16" off. At first I thought the strut bent as a result of the shaft breaking, but now I'm not sure. It never appeared bent before. The only time I've ever hit anything substantial in the water was about three years ago when I hit a manatee under full power, out in the middle of the river. Unfortunately, the manatee was either killed or had one heck of a headache. It felt like the whole rear end of the boat was going to be gone, but when I finally made it to the ramp, nothing was broken, or appeared bent, even the propeller seemed unscathed.

It seems as a minimum that a shaft and strut has to be replaced, and the whole assembly aligned. The don't know that much about the seal, but seems like it should be either replaced or upgraded while everything else is being done. Is this a job best left to the pros, or is fairly straightforward. Would SkiDIM be the best source for parts, or are these parts best, or only obtained from a dealer?

'88 Mastercraft Tristar, Indmar 351, Borg-Warner 1:1 transmission, stock 13x13 prop. The engine has 571 hours on it and is very well kept and maintained. Any thoughts? I've attached a picture of the results of my weekend.

09-04-2007, 10:41 AM
I've heard of this happening before. The shaft was mis aligned. Over time the metal fatigued and snapped.

09-04-2007, 11:54 AM
All the parts shoul be available from skidim.

H20ski Dude
09-04-2007, 12:22 PM
this happened on my old ski supreme. the shaft broke right off at the coupler though, not at the strut. I was barefooting at the time and went down fast. luckily the rudder saved the prop and broken piece of shaft from falling to the bottom of the lake.

we had nicks in the prop from it as well, so had that fixed while we changed to ski-dim's double tapered shaft system. not that hard really, but not cheap.

your seal should be fine, but you may want to replace it now anyways as its getting old.

your motor may be out of alignment too. I would suggest getting it aligned before spending too much time on the water with your new shaft.

09-04-2007, 12:29 PM
This happened to me a few years ago. My issued turned out to be much worse than I think yours can be. My stringers had rotted and the shaft was supporting the back of the engine and the shaft eventually let go. I realized what was wrong when things wouldn't line back up.

I don't think your boat has wooden stringers but there does seem to be an alignment issue.

I highly recommend the folks at skidim, great people to work with.

09-05-2007, 12:21 AM
Search the forums for "Propshaft Alighnment". This (http://tmcowners.com/teamtalk/showthread.php?t=8614&highlight=propshaft+alignment) thread, for example, has a good deal of helpful info on getting everything nice and aligned when you get the new hardware under there.

09-05-2007, 01:28 AM
I just ordered a new double taper shaft and hardware from Elbert (http://www.elberts.com/index.htm)'s. The shaft for my boat is 1" diameter and 48" long. It was $300 for shaft, nuts, keys, flange and the special nut to remove the flange.

I talked to them about my strut, and it seems to be fine, so I'm going to go ahead and try to do the alignment with it. If I can't get things to line up, I will replace the strut. The strut is around $300 also - YMMV - mine is an older 16 degree unit.

09-05-2007, 09:13 AM
Thanks to all for the insight. I guess breaking a shaft is not as odd as I had thought. I'll be gathering the parts soon and will decide whether to tackle it or not. The alignment of the engine, shaft, and strut does seem to be the key.

09-05-2007, 09:27 AM
If the seal doesn't leak, it probably won't need replacement, but with a new shaft, it will need adjustment. If you mean the packing, go ahead and replace it. Mark a centerline for the strut on the hull with a Crayon or something that can be removed, then sight through the strut through the opening for the shaft. My guess is that it's twisted from hitting the manatee and the rear of the strut is closer to the passenger side of the boat than the front.

09-05-2007, 10:03 AM
In talking with the folks at Elbert's, it was mentioned that you can use the old shaft to do some minor twisting/straightening of the strut. If the bend or twist is not bad, you might consider giving that a try.

09-05-2007, 12:00 PM
"it was mentioned that you can use the old shaft to do some minor twisting/straightening of the strut."

How much more stress do you want to put on the hull? Check to see how far off it is. If it's not much, leave it, re-position it so it's more in alignment with the shaft/transmission coupler and re-align the motor. It's a casting- they don't like to be twisted. The shaft broke at a point of major stress. That tells me that the strut is wanged. If you have insurance, use it- that's what it's for. Shaft, strut, installation, alignment, additional parts and labor should be over your deductible. Have the prop checked, too. The new shaft will come with a coupler, too. Use it- the old one will not be a great fit and you don't want them to be mis-matched.