Thruster Shear Pin Question

[R Baker]

I Have searched for an answer but to no avail. So .... Discussion of shear pin replacement suggests to me that this something I may (probably) have to deal with. Why are shear pins failing ? Presumably because something like a bit of wood or line gets sucked in and jambs the propellor. If this so, cannot the opening be screened to prevent debris from getting sucked in. Are pins failing more in salt water or fresh water? Thanks.
RB

 

[elly]

The bow shear pin just failed on my R25. The shear pin does not get wet so I doubt fresh/salt water matters. In my case I think failure was caused by the stress when I was using the thruster in a wavy dockage. When the bow came out of the water the thruster prop spun up and when it fell back into the water the prop grabbed and that created torque on the pin. The pin did not fail then but soon after.
BTW, on the R25 it is surprisingly easy to replace the bow pin. The second time will only take 20 mins.
Be sure to add retaining clip pliers to your toolbox to remove and replace circlip.

 

[Captain Steve]

Mine broke and was advised by the factory to pause just a second when shifting the thruster from port to starboard. It was an easy fix as long as you have the right tool. I think it was a 6 mm hex. There should be a spare clipped to the housing.

 

[jroyle]

On the 2012 R29 my thrusters have a built in delay when moving from port to starboard..Saved me many times when changing directions..

 

[SnugTug]

Replaced my bow thruster shear pin today on 2015 R-27. Not too difficult with proper tools. Be sure to have correct size spring clip pliers or you will struggle as I did with small vise grips and needle nose pliers. I also had to tap home the replacement pin to get it seated properly - this made me nervous because I had not expected it to be such a tight fit. Hoping I did it right. Thrust restored.

PS - Spare shear pin was clip to port side of motor. Looking to order spares now.

 

[trailertrawlerkismet]

RB:

Some boats do have screens built in or added to the thruster tubes to prevent debris from getting into the prop and causing the shear pin to snap. Screens would make for more holes in your boat, potential for water penetration and then they'd need to be removed when you needed to replace zincs, clean barnacles and or bottom paint. Personally I'd rather not have screens for these reasons. You could go one day or 5 years without having a shear pin break, its all a matter of luck or no luck while you're boating. As an example I'd never had to replace a shear pin in a thruster for 4 full years on our R27 and 4 years on our prior boat.....then one day earlier this month I sucked up a mooring ball line into the bow thruster and instantly broke the shear pin. It's good that they break because if they did not then it would be the prop or mechanics of the unit that might and that would be more expensive to repair.

Jim