Bow thruster sheer pin replacement

B

bpeatman

Member
Joined
Jun 13, 2023
Messages
18
Fluid Motion Model
C-30 S
Hull Identification Number
FMLT2907H213
Vessel Name
Sugar
MMSI Number
338482189
Hello
I have a 2013 29S Ranger Tug and unfortunately a line sucked into my bow thruster and I'm told I need to replace the sheer pin. I've searched and have not found any DIY videos or part information.
Is there as specific part I need to order? Thank you!
Bill
 
Bill,

It depends on what brand of bow thruster you have. I have the side power n my 2015 Cutwater, and some other boats have a Lewmar. The Fluid Motions factory rep should be able to give you this information. You can also sign into the TugNuts site and then do an advanced search, use the upper right of the page search box, by typing in "bow thruster shear pin." You should get access to a number of threads on this subject.
If you can find out the brand and model number, you can go to the specific manufacture's website and get the information regarding pin replacement, including part numbers.
Some suggest to replace the pin with a stainless steel pin instead of the standard brass pin as it doesn't shear off as quickly but that may defeat the purpose of the pin protecting the motor, prop, etc.
I'm not sure about Lewmar but Side Power requires a special rachet with a built in Allen wrench to disassemble the unit. They sell this on their site or should be able to direct you to someone who can sell you this tool.
The bow thruster is generally located in the front birth/stateroom under the floor/bed storage panels.
I hope this helps.
Terry
 
bpeatman":i0pbvrg9 said:
Hello
I have a 2013 29S Ranger Tug and unfortunately a line sucked into my bow thruster and I'm told I need to replace the sheer pin. I've searched and have not found any DIY videos or part information.
Is there as specific part I need to order? Thank you!
Bill
Click to expand...

I had to replace my forward bow thruster shear pin a couple of years ago. Luckily the bow is much easier than the stern. You probably have the same Side Power thrusters as my 2011 R29 and it wasn't very hard. The low profile ratchet helps and you'll need a set of snap ring pliers. Here's a video showing how to replace the shear pin. https://youtu.be/GXH7CvFTsnw My motor was accessible under the v-berth. Lots of room to access.
 
Lewmar front thruster pin replacement is very easy. Only tool I needed was a 1/2 wrench or socket.
Good luck
 
CaptT":1j3nqex9 said:
…..Side Power requires a special rachet with a built in Allen wrench to disassemble the unit. They sell this on their site or should be able to direct you to someone who can sell you this tool……
Click to expand...

The tool in question is a Chapman CM-13 1/4” Drive Mini Ratchet with a 6mm hex bit. Is it absolutely required? No. Does it make the job easier? Yes.

https://chapmanmfg.com/products/famous- ... chet-cm-13

If you buy from Chapman, you will have to buy ratchet with a set of bits that includes the 6mm hex for $21.

https://chapmanmfg.com/products/2

To buy from Imtra with just the 6mm hex bit, it’s $27:

https://www.imtra.com/products/product- ... ctid=25943
 
Thank you for the replies. Did any of you replace your pin with the boat in the water? I have a diver who has done pin replacements but isn't sure about the access to this particular thruster.

Also, one yard recommended, if I have to haul it out anyway, replacing the propellers on both thrusters with stronger ones that improve thrust 30% (his claim). Any of you have thoughts on that?

Haulouts where I live run over $400 (about $15/ft). If I can't fix it in the water, another option is to wait til I need bottom paint. I don't really need two thrusters where I boat but I sure like them!

Finally--my marina manager very nicely offered to lift the boat on a spare hydro hoist but wasn't sure of the capacity of the hoist. Wondering if we just lifted the boat a foot or two if that would be safe.

THanks everyone!

Also it is a sidepower thruster.
 
Shear pin replacement can be done with the boat in the water.
 
I have replaced both bow and stern thrusters in the water without any issues.
Our 2015 R31 Sidepower thrusters came originally with brass or bronze shear pins.
The ones you get now from Sleipner/Imtra are stainless steel and seem to hold up better than the softer, original shear pins.
 
As others have said, shear pin replacements can be done in the water (the pins are accessible from inside the boat only) and any decent diving service should be able to replace your thruster props in the water since they routinely remove and install propulsion props with boats in the water. I would be careful about replacing your thruster props with anything other than OEM props. If the props are pitched differently, the extra thrust could over torque the motors and/or will cause you to blow through shear pins.
 
So now I'm getting confused.
I talked to one mechanic and showed him the tool and the pin recommended by Ranger Tugs:
https://www.imtra.com/products/sleipner ... ctid=36530
But he said that's the sheer pin accessible from inside the boat but 9/10 it's the drive pin, which is located behind the propeller, not the sheer pin which is between the motor & driveshaft as seen on page 7 of this manual.
https://yachtaidmarine.com/wp-content/u ... tected.pdf
I fear I ordered pins and a wrench for the wrong problem.
 
I have followed Tugnuts since 2012. In that time, I have seen a number of posts on shear pin failure. I have not seen a single report on drive pin failure. I have changed the shear pins on both the stern and the bow thrusters. The 9/10 claimed by your mechanic seems wrong to me. A good policy regarding mechanical repairs is to check the easy stuff first. Before I went ahead with checking the drive pin I would certainly check the shear pin, an easy job for a bow thruster. Shear pin service does not require the skill level of a marine mechanic. For a bow thruster it would take me less than 30 minutes start to finish.
Regarding a change in props, I think the caution mentioned by Bob Menches makes good sense.
 
Thank you so much. That is super helpful. Last question (maybe).
How do you access the thruster inside the boat?
 
bpeatman":1y1j5ct3 said:
Thank you so much. That is super helpful. Last question (maybe).
How do you access the thruster inside the boat?
Click to expand...

Remove the forward cushion in the v-berth (removing the port side and forward cushion'ed headboards will make it easier to remove the v-berth cushion). Remove the plywood floor to access the forward thruster. You may have a sheer pin mounted on a plastic holder on the thruster motor. The sidepower video I posted earlier should complete the process.
 
Thank you all. I will report my findings when I next visit the boat.
 
Hi All

I finally replaced the sheer pin and unfortunately that did not solve the problem. The motor works, the boat side of the thruster where the sheer pin connects spins, but when I turn on the thruster I get a lound whining sound like screaming wheeeeeeeeeeeeeeeeeeeeeeeeee and no movement of the boat, which was the same symptom before the sheer pin replacement. Any recommendations welcomed. I did the sheer pin myself so I have not had a mechanic look at it yet. Wondering if I need a mechanic or a diver or a haulout or some combination. THanks in advance.

Bill
 
I had the gear box go out from water intrusion. That could be your problem and you have to pull the boat to replace that.
KKRCRACE
 
The next step would be to check the propellor drive pin. (I am assuming here that is original shear pin was not broken and that the drive coupler was free to turn).
Download this document: SE60_IP_Manual.pdf (imtra.com). Take a look at page 7 to see what is involved. I expect it is quite difficult, but not impossible for a skilled person to remove the propellor with the boat the in the water. If this were my boat, I would go for a haul out. The pin is available from Imtra. This is probably a good time to have a conversation with Imtra’s customer care staff.
What you do not want to do is to continue testing the thruster while there is a disconnect between the motor and the propellor. Very short pulses are okay. For longer operation the motor’s RPM can reach excessive (damaging) RPM.
 
bpeatman":34mapboe said:
Thank you. I have the SE 40 but it does not show a pin like the SE 60. I do have a diver coming to take a look he says he has done thruster repairs in the water before but not this brand.
https://www.imtra.com/DocumentManager/P ... Manual.pdf
Click to expand...

Look at Page 7 of the installation manual. You will see directions of proper alignment hight of the gear housing to the motor bracket. The gauge provided for installation sits in the shaft slot for the drive pin. Step 3 Place the motor assembly gently on the motorbracket. Make sure that the drive pin in motor drive shaft fits the into the corresponding grove in the gearleg shaft. Be careful, the motor is heavy!

Look at the propeller hard wear. The shaft is splined and the prop is held on by the lock nut. The only thing that could be broken is the splines on the plastic prop or the prop is missing. I would pull the motor and inspect the shear pin again.Previous installation of the pin, when the motor was off did you spin the gear case shaft to confirm free smooth movement. This will tell you if you have a gear case failure without hauling the boat or hiring a diver. When you inspect the shaft movement and it feels smooth no binding then inspect the motor to gear housing alignment and confirm that the elevation is not marginal. I have seen and heard of poor factory installations that have caused shear pin failures because of poor alignment. After all these checks a quick jump in the water ( thruster battery switch off) grab the prop and spin it. It should turn with resistance because you are turning the pinion and shaft gear and motor. If it turns real easy I would say the prop splines are gone. This would unlikely.

My bet would be shear pin, next poor alignment, next bad gear case.
 
Thank you. When I removed the sheer pin it did not appear to be broken. I replaced it anyway and the symptom was the same as before. I high whining sound and no thrust. I did spin the shaft when I removed the motor and it moved smoothly.
 
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