Bow thruster problem

[Observer]

Bow thruster inop when I arrived yesterday morning. Fuse had blown so replaced that. Motor now turning but no thrust.

Replaced the shear pin - the old one was in bits so that was deffo (a/the) problem. Operated again - seemed okay for a second but then whizzed again so assume shear pin broken again.

I assume this symptomatic of problem in the prop tunnel - blockage, alignment etc. Any other possibilities I should consider?

 

[Nick_H]

Yep, almost certainly a fouled prop, rope or something. Could be a seized gearbox, but unlikely as they are v simple and not much to go wrong. Also unlikely to be alignment as it worked previously. I'm afraid it's a mask and snorkel for you my friend.

 

[neale]

Take the motor off so you can access the shear pin. You should be able to turn the shaft now by hand. This will tell you if the prop is fouled or lower leg is faulty without getting wet.

 

[mjf]

Wow - odd problem. Where did you source the spare pin?

If its free to turn by hand then clearly the motor will have no problems. Is the back of the prop OK where it locates with the shear pin?

 

[Observer]

Take the motor off so you can access the shear pin. You should be able to turn the shaft now by hand. This will tell you if the prop is fouled or lower leg is faulty without getting wet.

Yep - did that and the shaft was rotating with what seemed to be the 'right' amount of resistance. Spoken to Vetus dealer now and there is also a "drive pin" behind the prop which is designed to fail (but after the shear pin). I guess the prop could be blocked but a broken drive pin is still allowing me to rotate the shaft?

Only other explanation is a failed gear but that's apparently unusual and doesn't go without warning signs, that we haven't had (I don't remember anyway).

Apparently new drive pin is an easy fit so should be able to DIY during a lift at Sealift Cowes.