Jump to content

HELP - my prop shaft has come out


Strettonman

Featured Posts

The joys of being new to boating ?. Bought this old boat and have been gradually getting it home. The prop has always been a little rattly on tick over but today I thought it was a little worse. After about 4 hours of boating we tried to come out of a lock and it wouldn’t engage the prop. On investigation prop has moved back out of the coupling to the fear box. Fortunately the woodruff key was still in the coupling. Prop can move back and forth (only dared moving an inch or do). I can line everything up and give the prop a shove or whack with a mallet but only engages with coupling a few mm. 

can I just take the coupling off the gearbox, push into prop an inch or so with the key in place and then push the lot forward to rebolt to the gearbox ? 

Also, for my learning what stops the prop from pulling out when you are in hard reverse ? Do I need to check  for anything else. 

Link to comment
Share on other sites

I don't know that coupling but in the absence of someone who does, I would be investigating what is inside the rearmost section by removing the locknuts and pulling it off. I would expect to find some sort of collet arrangement that squeezes the shaft to grip it.  You may need to loosen the nuts that tighten the stern gland to get enough movement on the shaft to bring it closer to the gearbox when you know how it goes together. You will be able to push the prop better from inside the weedhatch.

Hopefully someone with knowledge will be along soon.

Link to comment
Share on other sites

My initial reaction is that the coupling on the gearbox is remarkably close to the nut on the stuffing box.  It really looks like the separation is little more than the diameter of the shaft, so possibly only 1.5", and certainly no more than 2".

 

The engine is on flexible mounts, so can rattle around, whereas the stern gear can't - not unusual but there is usually more length of shaft, so the stresses on the shaft would not be as great - yours needs very good alignment.

 

Unless the alignment is perfect it's going to be hard to persuade it back in, and it seems possible to me that the engine may to a degree have been supported by the shaft, and may have dropped slightly when it came out, meaning the two are no longer truly in line.  Does the shaft look like it will pass into the gearbox coupling, or is it possible it is actually coming up against the back face of it?

Link to comment
Share on other sites

8 minutes ago, alan_fincher said:

My initial reaction is that the coupling on the gearbox is remarkably close to the nut on the stuffing box.  It really looks like the separation is little more than the diameter of the shaft, so possibly only 1.5", and certainly no more than 2"

Lifting the weedhatch and checking where the prop is would tell us if the whole shaft and prop is more or less in the right place or if it has moved backwards.

18 minutes ago, RLWP said:

You can just see a dimple in the shaft, half out of the stuffing box. Id there a grub screw somewhere on the coupling to engage with that?

So that is not the keyway you can see?

Link to comment
Share on other sites

He say's that the key is still in the coupling so the dimple on the shaft must be for a securing grub screw or bolt. The keyway slot must be out of sight underneath and run off the shafts end for it to leave the key behind in the coupling.  That type of coupling were often made slightly undersize,  heated up and shrunk on but would still have the security screw and dimple on the shaft.

 

Link to comment
Share on other sites

I had something very similar happen to me many years ago when the boat was fairly new. On Vital Spark the shaft went into the coupling and was prevented from coming out when reversing by a grub screw. I suspect your set up is the same. Check all around the circumference for a small grub screw. My grub screw was small and socket headed. If I recall correctly I persuaded back in using a boat pole down the weedhatch. You might find it easier to split the coupling. Once fixed , try not to use reverse as this is what pulls the shaft out. As a long term fix I drilled the grub screw thread out, re-tapped it to a larger size bolt in making sure it went into the shaft a few mm. I also pit an other one in at 180 degrees for balance

 

Hope this helps

 

To stop the shaft dropping too far back see if you can get a jubilee clip around the shaft just in front of the stuffing box

 

Edited by Slim
Link to comment
Share on other sites

Thanks very much everyone. I’ll look for the grub screw in the morning. The shaft is petty well aligned as it goes into the coupling but too tight and I can’t get enough force on the end of the prop to push it further. 

I will try the pole idea (did try with a block of wood but couldn’t get enough purchase. If I do get it back in will try the jubilee clip and chug her home gently. 

Thanks again. 

 

Secretly I’m enjoying the challenge ?

Link to comment
Share on other sites

 

 

1 hour ago, Strettonman said:

Thanks very much everyone. I’ll look for the grub screw in the morning. The shaft is petty well aligned as it goes into the coupling but too tight and I can’t get enough force on the end of the prop to push it further. 

I will try the pole idea (did try with a block of wood but couldn’t get enough purchase. If I do get it back in will try the jubilee clip and chug her home gently. 

Thanks again. 

 

Secretly I’m enjoying the challenge ?

Forgot to mention , if you find a grub screw don't forget to back it off so it doesn't obstruct the shaft..

Sorry but you can't claim it's a challenge until you're crouched over it in the pouring rain frozen stiff

Link to comment
Share on other sites

Until you get it properly fixed, don't use reverse gear. Not at all. Not even once. You will have to learn to strap the boat in locks, approach moorings very slowly, drop the gear into neutral then leap off with a rope. Only in reverse gear will the shaft pull out of the coupling.

Link to comment
Share on other sites

Thought I’d posted this last night. ——-

Thanks very much everyone. I’ll look for the grub screw in the morning. The shaft is petty well aligned as it goes into the coupling but too tight and I can’t get enough force on the end of the prop to push it further. 

I will try the pole idea (did try with a block of wood but couldn’t get enough purchase. If I do get it back in will try the jubilee clip and chug her home gently. 

Thanks again. 

 

Secretly I’m enjoying the challenge ?

Link to comment
Share on other sites

Thanks all. Got it sorted this morning. Found the grub screw in the bulge water. Managed to push the prop on about 1/2 an inch using the pole as a lever and wiggling the prop at the same time. Started the engine and (very gingerly) put it into drive. The prop went all the way home straight away and the grub screw hole lined up perfectly. 

 

Fitted grub screw screw securely and tried reverse on tick over. No problems at all. 

 

AMAZING !!!!!!

 

will still follow the advice about avoiding reverse. 

 

Thanks so much to you all. Hopefully another happy day of boating. Just need the sun to shine now???

Link to comment
Share on other sites

14 minutes ago, Strettonman said:

Not spending any money is the best bit of all. 

Will look at loctiting in the grub screw. 

 

Cheers

 

Is the grub screw as long as the hole in the coupling? Sometimes, instead of one long grub screw there are two short ones fitted. One locates the shaft and the second locks the first

 

Richard

  • Greenie 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.