Vetus Bow Thruster 5512 on Narrowboat

[chilterns]

When "nudging" into my birth with the Bow Thruster there was a loud "screech" and it stopped working.

Has anyone any ideas what could be wrong ?

Could this be debris jamming the propeller and causing the shear pin to break ?

 

I have read somewhere that the motor can be removed (4 x 6 mm Allen bolts) to replace the shear pin while the boat is in the water ?

The question I have with this is that the water level is 250 mm. above the base plate of the motor, so does that mean the water WILL enter the boat 

 

 

[Tony Brooks]

The manual suggests that the drive pin is securing the propeller to the shaft, NOT the motor shaft to the bevel gear shaft, so I think that unless your boat has been fitted with a weed hatch or a partial bulkhead to allow the whole assembly to be removed while afloat, it will need at least the front taking out of the water.

[Alan de Enfield]

11 minutes ago, chilterns said:

When "nudging" into my birth with the Bow Thruster there was a loud "screech" and it stopped working.

Has anyone any ideas what could be wrong ?

 

 

I would suggest that if you got a loud screech, then the shear pin may not have failed and the prop was trying to turn with the piece of wood (or whatever) jamming it in the tunnel ?

When I have had shear pins go it generally goes from turning to not turning with no noise or drama - as soon as it feels resistance it just 'fails' (as it should)

 

Do you have a mesh over the external ends of the tunnel ?- that should limit the size of anything entering the tunnel.

[Tracy D'arth]

Complicated if you cannot safely remove the whole thing without sinking the boat. The pin is in the impeller inside the tube so well under water.

Is it in a watertight well compartment of its own?

You could always learn to boat without it until the next docking.

[chilterns]

Sorry Tracy and Alan, I forgot to mention, the motor still runs when operating the right or left button, but no movement of the impeller.

 

Not sure about grill or mesh over the tunnel until I get down there with my waders.

Thank you Tony. Looks like it has to come out of the water then.

[pearley]

16 hours ago, Tony Brooks said:

The manual suggests that the drive pin is securing the propeller to the shaft, NOT the motor shaft to the bevel gear shaft, so I think that unless your boat has been fitted with a weed hatch or a partial bulkhead to allow the whole assembly to be removed while afloat, it will need at least the front taking out of the water.

You're correct. The prop is located over the shear pin and secured by 2 stainless steel self tapping screws. Our previous boat had a weedhatch but I would say almost impossible to actually replace the pin whilst in the water through it.

 

When a bit of 2 X1 managed to get past the grille it took one blade off the prop rather than break the shear pin.

[chilterns]

Thank you Tony. Looks like it has to come out of the water then.

Thanks pearley for that cheerful thought. Presumably you lift the whole thing out when it's out of the water.? I just hope the prop isn't damaged. As the motor is still running hopefully it's the shear pin.

[matty40s]

You will probably find it's easier to replace it through the tube, the whole mech doesnt necessarily lift out.

You will need a very long extension socket to unscrew the 2 retaining screws though.

Edited May 16 by matty40s

[chilterns]

Thank you matty for the advice, I will bear that in mind.

[pearley]

3 hours ago, matty40s said:

You will probably find it's easier to replace it through the tube, the whole mech doesnt necessarily lift out.

You will need a very long extension socket to unscrew the 2 retaining screws though.

Or very long arms!

 

If you replace it yourself then make sure the pin sits horizontal otherwise it can drop out as you put the clamshell bits if plastic over.

Edited May 16 by pearley

[matty40s]

If you are really lucky, you might find one of these.

 

The pin sits behind the prop with this one.

 

7 minutes ago, pearley said:

 

If you replace it yourself then make sure the pin sits horizontal otherwise it can drop out as you put the clamshell bits if plastic over.

Take a tub of grease and liberally coat the pin, it will help it to stay in place until you get the clams shut.

[chilterns]

Thanks matty. Is the image of the prop what I would expect to see in the tunnel.? Is that also the shear pin in the image. Are you saying all the bits in the image come as a kit with the new prop. Looks like I will need to get everything together so I don't have to take it out of the water more than once.

[matty40s]

Looking at the manual, you have the single bolt/nut fastening as pictured above. The split pin goes through the driving shaft behind.

 

17 minutes ago, chilterns said:

Thanks matty. Is the image of the prop what I would expect to see in the tunnel.? Is that also the shear pin in the image. Are you saying all the bits in the image come as a kit with the new prop. Looks like I will need to get everything together so I don't have to take it out of the water more than once.

Yes, looks like that's the one, Cheshire Marine are where we usually get our stock from.

[pearley]

Mine didn't have a central nut.

[chilterns]

So the hole in the shaft in the diagram is where the split/shear pin fits.? If that's the case for the 5512, then it looks as though it could be replaced in the water with my waders on.? Although bearing in mind what pearley said about not having a central nut, what other fixing would it be.?

Another thought occurred to me if I was doing this in the water, how would I hold the shaft whilst removing the nut then refitting the nut.?

[matty40s]

53 minutes ago, chilterns said:

So the hole in the shaft in the diagram is where the split/shear pin fits.? If that's the case for the 5512, then it looks as though it could be replaced in the water with my waders on.? Although bearing in mind what pearley said about not having a central nut, what other fixing would it be.?

Another thought occurred to me if I was doing this in the water, how would I hold the shaft whilst removing the nut then refitting the nut.?

 

Pearleys propellor is more difficult, especially underwater, I would have though impossible.

It has 

 

2 screws holding the two halves together. When you undo the screws(stainless steel so NOT magnetic), the two halves swivel out on pins allowing you to remove prop and access to the split pin behind.

These are less robust than the first type, as either or both the halves can get destroyed, loosening prop and giving you the symptoms you are experiencing.

 

 

You can either order both, and send the incorrect one back, or try to get a go pro camera in the tube to see which you have.

Doing this in the water ...

You need to remove the top unit(6 allen key bolts) and then secure the splined shaft from the top of the leg with grips against a bulkhead or another human holding grips.

[chilterns]

Great information matty, however herein lies the problem when attempting the job with the boat in the water. The water level is 250 mm. above the base plate of the motor. As to the type, if the prop is pointed to the shortest end of the tube I would be able to feel which type it is, as the thruster is not central in the width of the boat. If pointed towards the longest end it wouldn't be possible.

[pearley]

27 minutes ago, chilterns said:

Great information matty, however herein lies the problem when attempting the job with the boat in the water. The water level is 250 mm. above the base plate of the motor. As to the type, if the prop is pointed to the shortest end of the tube I would be able to feel which type it is, as the thruster is not central in the width of the boat. If pointed towards the longest end it wouldn't be possible.

No weedhatch?

[chilterns]

Afraid not, not in th bows anyway

[blackrose]

17 hours ago, matty40s said:

You will need a very long extension socket to unscrew the 2 retaining screws though.

 

It depends where it's mounted in the tunnel. It doesn't have to be in the centre. Mine is on one side and very easy to access from the tunnel opening and take the retaining screws out with a screwdriver. Having the BT offset in the tunnel doesn't affect its performance.

12 hours ago, pearley said:

Mine didn't have a central nut.

 

Neither does mine, but mine's a 95kgf

 

The two semicircular plastic clips are held in with screws and then the prop comes straight off. There's a recess on the back of the prop that fits over the shear pin.

[pearley]

4 hours ago, blackrose said:

 

It depends where it's mounted in the tunnel. It doesn't have to be in the centre. Mine is on one side and very easy to access from the tunnel opening and take the retaining screws out with a screwdriver. Having the BT offset in the tunnel doesn't affect its performance.

 

Neither does mine, but mine's a 95kgf

 

The two semicircular plastic clips are held in with screws and then the prop comes straight off. There's a recess on the back of the prop that fits over the shear pin.

Mine was a 60 kgf. Current boat is 95 but not had it out of water yet.

[chilterns]

Thanks blackrose. Mine too is offset so easy to get to and as I said, OK if the prop is pointing in the same direction. I haven't looked yet, so don't know if there is a grill over the tunnel and if there is, how would it be fixed.?

All this is academic with the boat in the water if I can't stop the shaft from turning while I remove and refit the nut. I think maybe it would be different if it were the two screws, as I could just hold the prop to stop it turning while I removed the screws.

Am I assuming I can remove the motor (allen key bolts) with the boat in the water, without water coming in (water level 250 mm above base plate)?

[cuthound]

48 minutes ago, chilterns said:

 if there is a grill over the tunnel and if there is, how would it be fixed.?

 

 

On mine the grilles are held on with two bolts. See the image below.

 

 

Edited May 17 by cuthound
Buddy spilchucker interfering

[matty40s]

1 hour ago, chilterns said:

 

Am I assuming I can remove the motor (allen key bolts) with the boat in the water, without water coming in (water level 250 mm above base plate)?

Yes you can, the leg and splined shaft are sealed to the underside of the tube, and held in with separate bolts(2).

As I said previously, just get some large grips on the splined shaft to stop the prop rotating.

[chilterns]

Thanks cuthound I will have to investigate when I get my waders on.

Thanks matty. Sounds if it's possible with the boat in the water. A simpler job if it's a nut and not screws.