prop shaft decided to leave via the back door

[nmptwentyone]

my prop shaft decided it liked it better in the water, disengaged and shifted rearward. couldnt fully come out due to the rudder blocking it, which i hope is due to design not fluke. i managed to find the key, loosen the grub screw, opened the weed hatch and shifted the whole thing back from whenst it came. ive locktited the grub screw. only one though? have turned the shaft in both directions also tried pulling on the prop from the weed hatch, seems pretty solid, dont move. was wondering if its worth drilling another hole and tapping for another grub screw? is it standard to just have one?

[Keeping Up]

I assume you mean the grub screw in the bearing? The bearing on mine has tapped holes for 2 grubscrews but only has one screw. The last guy who worked on it said it only needed one, which was his way of saying he'd dropped the other one and lost it. It doesn't do very much really, the propshaft (on mine) relies on being well and truly fixed to the flexible coupling with several big bolts and all the thrust goes through them. A littel grub screw wouldn't be strong enough to do that job, so I guess one should be enough.

[John Orentas]

There are several ways of retaining the prop-shaft but if you are saying that a grub screw simply grips the shaft. The best way this should be done is to carefully drill into the shaft for a couple of millimetres to give a recess for the screw rather than relying on friction. While you have access it would not do any harm to fit a second screw. Oh yes Locktite everything.

[nmptwentyone]

I assume you mean the grub screw in the bearing? The bearing on mine has tapped holes for 2 grubscrews but only has one screw. The last guy who worked on it said it only needed one, which was his way of saying he'd dropped the other one and lost it. It doesn't do very much really, the propshaft (on mine) relies on being well and truly fixed to the flexible coupling with several big bolts and all the thrust goes through them. A littel grub screw wouldn't be strong enough to do that job, so I guess one should be enough.

thats the one. big bolts on coupling all very well untill you go full astern!

There are several ways of retaining the prop-shaft but if you are saying that a grub screw simply grips the shaft. The best way this should be done is to carefully drill into the shaft for a couple of millimetres to give a recess for the screw rather than relying on friction. While you have access it would not do any harm to fit a second screw. Oh yes Locktite everything.

the one thats in there has a recess on the prop shaft, think it got a bit damaged when it came out. think i will put a second in. dont hurt. wondering if its a common problem.

[Alastair]

Pop a jubilee clip around the shaft, just forward of where it exits the boat. This will stop it from falling all the way out if the same thing happens again.

[NB Phoenix]

This may be a daft question.... If it is... sorry.

 

When the shaft fell out were you in forward gear or reverse?

 

I can understand it coming out in reverse but not forward, unless you lost propulsion first.

[chinablue]

had same problem with my prop shaft ,as it was only months old ,took it back to boatyard and was given a modified bearing that had a clamp instead of grub screws much better job jim