Stern Thruster Sheer Pin Help

B

Bobby P.

Well-known member
Joined
Oct 17, 2018
Messages
440
Fluid Motion Model
C-302 SC
Non-Fluid Motion Model
Boston Whaler
Vessel Name
The Retreat
I think that I sheered the pin on my stern thruster (R-31).
I have an extra pin, but have not delved into the repair. We are currently underway and about 200 miles from home port.
Any suggestions before start ripping into it?
Thanks,
Bobby
 
I just went through changing the stern thruster sheer pin in our R-29s. First tip is you need to support it as you remove and reinstall the motor. I used the boat hook across the opening and a tie down strap. Second the ratchet tool provided has very little clearance, however does work. A fair amount of patients, brakes, and bleeding knuckles are required. We were in Big Bay, Stuart Island, B.C. when this happened. I drew a small group of spectators during the process, who I'm sure enjoyed the show. 1 1/2 hours later I engaged the thruster and it was working as normal. Lost less than 1/2 a pint of blood so it was a success.
 
I just did this about a week ago. I previously watched a mechanic replace my shear pin a year ago. My R31 has a Side Power thruster.
The Imtra replacement instructions are located here: https://www.pocketyachtco.com/wp/wp-con ... _30_40.pdf

I found that I needed 1) a tension ring removal tool 2) 3 mm punch 3) 6mm "stubby" allen wrench.

Follow the directions above. I 1) turned off the thruster power 2) disconected the power cables and taped the terminal ends with electrical tape. Color coded is better 3)remove control cable 4) remove two allen screws. The one on the port side was more difficult for me to remove because of limited access. 5) Pull the entire motor unit out. Vacuum up dust in the gear drive and motor. Remove the old shear pin and remnants from the shear pin. 6) Use 3 mm punch to remove final remnants from the motor drive.

Follow directions above for reassembly.

Re-attach electrical supply cables and control cable. Turn on power. Test your work.
 
I'm not sure about the R-31. You might have more room than my R-27. But you may also have more stuff to get in the way.
I had to disconnect my cockpit scupper hose and some other stuff to get good access. So be prepared.

Re-installation is not quite as simple as removal. When putting the thruster back in place, you have to line up the fork that straddles the new pin AND the collar on the flange that nests into the recess on the other flange AND then the two bolt holes. All the while when you are supporting the rather bulky thruster.

My solution was to get two metric bolts (I forget, 6m or are they 8m) and cut the heads off. Don't worry about the material, they are just temporary alignment helpers. I screw these studs into place so now the alignment tasks are a bit easier, then put a nut loosely onto one of the studs as soon as you get the motor slid into place. Then you can "leisurely" remove the other stud and reinstall the proper bolt without having to hang upside down with sweat in your eyes and all the blood rushing to your head. Then the second bolt is easy. Snug them up and you're done. Don't forget to re-hook-up the scupper drains.

I kept the helper studs onboard in case I need them again. Sure enough two years later I sheared the bow thruster pin. The bow thruster is in a totally invisible to the naked eye location. You can put your hands down there, but not my fat old head. I stuck my camera down there, took a photo and was able to do the entire job "in the dark" using the studs.

Good luck, take your time and have a cocktail ready for when you are done.
 
Thanks for the support and technical device. I'll be getting my knuckles bloody shortly!
Bobby
 
Did it! This is not too difficult of a job if you don’t mind being upside down for a while. I also wish I had longer arms.Thanks for the great advice, btw! I did not have the resources, so I could not make two threaded studs but I now see how that would be extremely helpful when you guiding the thruster motor back into place. Removing the motor was pretty straightforward. However, the clearance on getting those two screws out, particularly the right hand screw made me think this was going to be impossible. The little wrench that came with the boat worked pretty well. However I did get it stuck on the right hand screw and it took me a while to get it out. The only other thing I did which was not mentioned was to wrap a rope around the motor and tie it off above so that it could suspend the motor while I extracted the screws and then also it was very helpful to have the motor supported when I remounted the unit.

Total job took about2 hours.

Thanks for the support!

Bobby
 
Can someone please post a picture of the little wrench. Need to compare to what I have or now need.
 
The supplied RT tool does not work, on my boat there is not enough clearance to seat the hex head, in the bolt head. How frustrating is that!!! Should not have been that difficult a job, if a proper tool was provided to remove the two retaining bolts given the extremely tight space. The supplied hex head needed to be about 1/4” shorter and the job would have been a piece of cake! We all could all have been spared the bloody knuckles. Someone mentioned a stubby 6mm Allen wrench, seems like that will work. Amazon to the rescue.

Be sure to spray lube on all the threaded surfaces, will make reinstall easier, can finger tight the bolts much further.
 
I just changed the shear pin on the stern thruster on my 2012 R29 yesterday. I'm 6'5'' and 200 lbs, and getting into the space was a bear! That being said, the 6mm ratcheting Allen wrench supplied by Imtra worked perfectly once I found to do each bolt a few turns at a time and not try to get one bolt all the way out before starting the other. That only succeeded in jamming the wrench against the motor housing with no way to reverse the ratchet to move it back in. Luckily I was able to get my fingers in and turn it enough to free the wrench. Doing each side a little bit allows the motor housing to move keeping the wrench in clear space.
 
Has to be variability in years and models. I have a 2017 29CB, access to the thruster is good, getting wrench on bolt, not possible.

Trying this may work
MulWark 20pc 1/4 Ultra Low Profile Mini Ratchet Wrench Close Quarters Screwdriver ... https://www.amazon.com/dp/B07D4DZB1T/re ... DDbGM5F7AR
 
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