Bow thruster pins- help please

[jonlea]

I have a sidepower SP40 bow thruster which has stopped driving the propellor, although I can hear the motor turning okay. The manual says it could be either the shear pin broken at the top of the drive shaft or the drive pin broken on the shaft to which the propellor is attached. Is one more likely to be the cause than the other? Are the pins the same size? Can the shear pin be changed inside the boat when the boat is still in the water (the manual implies this but doesn't actually say it)? Any help or advice would be appreciated.

 

[Richard10002]

We have a Vetus bow thruster and the shear pin went in 2004 in bayona. We didnt have a clue what was wrong, or how to fix it.

Anyway, we took the top of the thing inside the boat, eventually got to where the shear pin was and that was the problem.

Easily fixed inside the boat... we got 4 new pins delivered to madeira from Vetus in Lisbon.

It went again on our arrival in Lagos in 2006 - very embarassing turning into the berth with the wind behind you!!

Crew were very impressed that I knew what was wrong, had some spares, and fixed it within about half an hour.

I dont know the sidepower but, if the shear pin is to do it's job properly, it should be easily accessible from inside the boat.

Can you find an exploded diagram of it?

 

[hlb]

Go for the one nearest the prop. Should be easily doable in water.

 

[jonlea]

Haydyn, I don't understand - the pin nearest the prop is in the tunnel on the outside under water - how would you be able to change that in the water?

 

[Talulah]

We also have a Sidepower unit. The pin used to go quite regularly and it was easily replaced. Remove the 4 allen head bolts at the bottom of the unit. Lift the motor and insert a new pin. We have never had the pin on the prop itself go.
Incidentally, the cause of pin regularly going was not due to so much load but because the pin was not sitting low enough. The bottom spindle was only catching about half the pin thickness and would shear off the bottom half of the pin rather than the whole pin. Finally I skimmed about 2mm off the base of the motor housing and it now fully engages. Not had a pin go since.

 

[jerryat]

[ QUOTE ]
Haydyn, I don't understand - the pin nearest the prop is in the tunnel on the outside under water - how would you be able to change that in the water?

[/ QUOTE ]

Purely for interest, I'd like to know that too! I don't have a bow-thruster but unless there's some sort of 'self-sealing' when the motor's reomoved. I would have thought water would enter the boat as the prop must be below the water? /forums/images/graemlins/confused.gif

 

[neale]

There are two pins in most thrusters, one on the prop shaft and one on the motor. The motor one usually goes and is easilt changed in the boat with the boat in the water. Just undo the four or so bolt that hold the motor onto the tunnel mounting and the motor comes away exposing the shear pin. No water will come into the boat!!

The one on the prop can only be changed by removing the prop and so will need to be done with the boat out of the water unless you have some scuba gear or are very good at holding your breath!!!

 

[AlanRD]

The shear pin should be the first thing to check and as stated is easy to fix with no chance of water coming in. Just keep to the four bolts holding the electric motor to the base and don't be tempted to try and dismantle the motor. There will probably be some chaff which should be removed to stop the water seals being damaged. The pin also has to be properly fitted in the shaft in the place provided or it won't work.

I don't know if the pins are universal but I bought mine from the UK distributers. There is a minimum charge by post so it is worth getting a spare and an anode at the same time.

Hope this helps.