Bow thruster shear pins keep snapping ? Anyone having this problem

[Gowiththeflo]

Hi all , Shear pins this the second year in a row ? What causes these pins to keep failing . I understand the concept but is any having this issue . Thanks in advance

 

[DennisG01]

Just thinking outloud... it's not a complicated piece of machinery, so, in no particular order:

-- Poor shear pin quality
-- Excessive drag in the motor
-- Changing direction too fast, too often
-- An obstruction

However, I wouldn't necessarily say (just yet) that you have a problem. Breaking the original shear pin and then a year later breaking the second one doesn't really qualify as "keep breaking pins", you know? It could just be that it was doing it's job as intended. Time will tell.

 

[HMBJack]

Only thing I can think of: Have you ever moved it left then right before the left stops rotating?

 

[Hookup1]

On my Vetus the prop shear pin is soft stainless to well "shear". I keep spares on the boat but have not has to use them. Not sure about the motor to transmission pin.

It's odd that the transmission pin would break and not the prop pin. I would call factory support for the thruster. Make sure you are using the right shear pins. Have spares.

Make sure the prop is tight to reduce rotational back-and-forth play. A washer, lock nut and a little dab of blue Locktite.

 

[Fishtales]

Never had an issue. Have you changed the zinc when needed? I've seen corrosion on the blades to the point they fall off on some boats. I'm guessing this does a number internally on moving parts - maybe making rotation more difficult. Do you have blade clearance in the tunnel? I've seen build up of bottom paint. Also as suggested usage side to side can be an issue.

 

[Meanwhile]

There is an Imtra guide to help diagnose the pin breaking. It is a pdf. I had to wrap a bit of tape on my pin holder as the pin had wallowed out the hole.

https://www.imtra.com/DocumentManager/ProductDocuments/Shearpin_Troubleshooting_30_40_60.pdf