Bow thruster sheer pins. How often?

[aviator]

I have just had my second sheer pin go on my Volvo bow thruster. Last one was around 3,000 miles odd.

Is this a common thing since it does give nasty scares and always goes when there is a bit of breeze or so it seems!

What do the panel think?

Richard

 

[hlb]

I have just had my second sheer pin go on my Volvo bow thruster. Last one was around 3,000 miles odd.

Is this a common thing since it does give nasty scares and always goes when there is a bit of breeze or so it seems!

What do the panel think?

Richard

Dunno, depends on the amount of twigs and logs you meet, it breaks to save the thruster motor from further damage.

 

[Nick_H]

It could be out of alignment. I had several couplings sheer in quick succession, and the boat had to be lifted and an engineer re-aligned it and it's fine now.

 

[hlb]

It could be out of alignment. I had several couplings sheer in quick succession, and the boat had to be lifted and an engineer re-aligned it and it's fine now.

Personally I've never found a use for one, seem to do more harm than good. Maybe ok for a single out drive, but there **** anyway. Just what does a bow thruster do, that two engines dont. Dont tell me I know all about it.

Bow trusters lead folk into doing the wrong thing in the first place, they have there uses, but maybe once in never.

 

[Deleted User YDKXO]

I have just had my second sheer pin go on my Volvo bow thruster. Last one was around 3,000 miles odd.

Is this a common thing since it does give nasty scares and always goes when there is a bit of breeze or so it seems!

What do the panel think?

Richard

Mine went last season for apparently no good reason at all. I think they eventually suffer fatigue and break. I always keep 2 spare ones on my boat

 

[Observer]

In general, I suspect it's as random as a stone chip on the car windscreen. May get several in a short space or go for years without any.

I had several shear pins (and fuses) go in relatively quick succession a couple of years ago. Found out that the one of the set screws that fixes through the flange that supports the motor and holds the leg of the thruster (the bit inside the tunnel) was working loose. That was allowing the leg to be misaligned so the prop was catching on the tunnel and blowing/breaking fuse/shear pin. The engineer diagnosed the thread on the leg as damaged/partlly stripped. If right, that could have been major expense of new leg (if available) or entire new thruster. Fortunately, on subsequent scheduled lift out, inspection of the leg showed that some muck/old mastic was lodged in the bottom of the threaded hole on the leg and this was stopping the set screw from tightening up properly. Cleaned out and been okay since, although did have to replace fuse and shear pin earlier this year, but that appears to have been a random occurrence.

 

[U4]

I have just had my second sheer pin go on my Volvo bow thruster. Last one was around 3,000 miles odd.

Is this a common thing since it does give nasty scares and always goes when there is a bit of breeze or so it seems!

What do the panel think?

Richard

At least your sheer pin broke - I am in the middle of having to have a whole new gear box and motor for mine as the sheer pin didn't break when I hit a log in the river so it has ended up wrecking the whole unit

Boat's currently out of the water having the work done (just as the sun starts to shine I may add).