View Full Version : Broken shaft-has this happened to anyone?
08-20-2013, 12:25 AM
I was cruising along last Wednesday at approximately 30 mph when I felt a slight bump, then it was like the boat was in neutral. Everything was fine, except no thrust. After getting a friend to tow me back to the dock, we discovered that the shaft had broken right in front of the prop. No major event like hitting a log or running aground preceded the shaft breaking. Over the 21 years of the boat's life I've wound a couple ski ropes around the prop, causing it to stop cold, and I've dinged the prop a couple times on my boat lift. But nothing worse than those events. Also lost was my $415 Michigan Wheel Ambush prop.
After getting the boat into my garage and pulling the shaft, I rolled it on the garage floor to see if it was bent. The shaft seemed to be dead straight.
Has anyone ever heard of this happening before? The boat is a 1992 ProStar 205, standard 351 Ford engine with 1:1 Velvet Drive. The shaft is 1" diameter and is heavy duty steel. Was it a manufacturing defect that took two decades to fail?
08-20-2013, 12:54 AM
I see reports of this once a year or so, a quick search finds:
1999 205V (http://www.mastercraft.com/teamtalk/showthread.php?t=52191&highlight=broken+shaft)
1983 MC Skier (http://www.mastercraft.com/teamtalk/showthread.php?t=44844&highlight=broken+shaft)
2007 X-2 (http://www.mastercraft.com/teamtalk/showthread.php?t=41019&highlight=broken+shaft)
2003 X-10 (http://www.mastercraft.com/teamtalk/showthread.php?t=31643&highlight=broken+shaft)
08-20-2013, 07:43 AM
This just happened in northern illinois... prop shaft broke right before prop...
08-20-2013, 08:30 AM
When was the last time you performed a powertrain alignment?
08-20-2013, 08:52 AM
Happened to me on my old S&S. Turned out that I had much bigger issues than just a broken shaft.
08-20-2013, 09:10 AM
It happened on an 89 powerslot at our lake. The prop was retrieved about 6 months later by another member who kept insisting he would find it,
08-20-2013, 09:15 AM
Yup, happened to a buddy's ski supreme. Check alignment for sure. Strut bushing too.
08-20-2013, 10:12 AM
I thought I broke my shaft once but I was ok once I sobered up
08-20-2013, 02:41 PM
Several years ago now, my prop shaft (1" dia. stainless) broke clean in two on my '88 Tristar also, although I didn't lose the prop.
I attributed it to a full speed manatee strike that happened several months previous (end of summer to next spring) so there was a long time between the strike and break, but not much motor time. The strut had an ever so slight bend in it (as I came to discover later), creating a stress to the shaft, but no damage to the prop blades at all, hence my thought at the time that no damage was done. I filed a claim with my boat insurance and they covered it. Replaced strut, shaft, cable, packing, and reconditioned prop.
When it gets replaced the strut, shaft log, and alignment should all be checked and brought into specs.
08-21-2013, 02:13 PM
Exact same thing happened to me except the shaft broke with a bang. Mine broke right in front of the strut bearing. Turns out my strut was slightly bent by previous owner causing a slight bending force on the prop shaft. The shaft only needs to be out of alignment a very small amount to cause problems over the long run. If you never checked your alignment over the life of the boat I imagine sagging engine mounts or even small bumps on the strut could cause enough misalignment to cause flexing of the shaft. My broken shaft was straight and had a clean cut just in front the strut bearing. The shaft will flex a bit without bending but I guess it's just like bending a piece of metal over and over, eventually it breaks. Cost me a new strut, prop shaft, and a prop rebuild to make it right. I spent an entire afternoon getting the alignment perfect on the install.