Bow thruster

[tshug]

I just recently bought a 2004 28Te and everything has been great on it until this past weekend when the thruster failed. Motor spins faster than normal but no thrust. The manual says it's probably the shear pin. I spoke with Vetus and sent them pictures of mine and Vetus thinks it's a 50 kgf, but the manual that came with the boat is a 55kgf. Vetus also said that the early 55's looked like the 50. The one I have has 2 screws on the top that I believe need to be removed to get the motor out to get at the shear pin. Is that all that needs to be done to get the motor out? Manual says to remove the power cables also, but not sure if that needs to be done. The other problem is that the 50 and 55 have different part numbers, the 50 is 3mm and the 55 is 4mm.

Any help would be appreciated. I had my first chance to dock it without the thruster and it wasn't easy! Got it done after a few tries and need more practice, but it sure would be nice to have the thruster back.

Thanks,
Ted

[Paddy]

Just went through this two weeks ago. Same year boat and 55kg Vetus thruster.

My local marine store matched up the Vetus shear pin with a Mercruiser "Quicksilver" 3 pack of aluminum shear pins for $9.50. They are meant for low hp outboards with 3hp-7hp, fit perfectly. Hopefully, you have the same one.

To remove:

1) Disconnect the power, mine cuts off through the battery switches
2) Take the cover off, two hand knobs that holds the grey plastic cover over the wires.
2) Allen wrench for the positive (i replaced this with a standard hex bolt)
4) Take the negative off, leave the smaller jumper wire on but be careful not to spin it while taking the main nut off for the larger negative cable (almost ripped it apart)
5) Disconnect the thruster direction cable (snap connector under the plastic cover)
6) Unscrew the two philips head screws but keep them in, they hold everything in place!
7) I stepped into the forward bilge to lift the thruster up from the bottom, better leverage...with the shear pin snapped, the interlocking drive end will fall off the bottom of the thruster with the clip, make sure it falls in to the bottom half and not into the bilge (I heard it drop into the base but it would have been miserable if it or the snap clip fell into the bilge.
8 ) Put the thruster and drive end to the side, check the base for possible pieces. I had 3 pieces total.
9) Take the snap clip off, slide the new shear pin in through the drive end and shaft, and put the clip back on
10) Line the drive up with the base, I turned the thruster and base until they lined up evenly with the philips screws.
11) Carefully drop the thruster in and make sure it seats properly
12) reassemble

As a side note, I was not a fan of those long philips screws, one was very difficult to remove and I needed to vise grip it out. I replaced both with 12" s/s 6mm rods and nuts. Made life much easier and I had the thruster back together in about 10 minutes.

Good luck

[Pitou]

Are you sure that you didn't lose the thruster prop? It's a possibility. Years ago that happened to me. Thought the shear pin broke and took everthing apart to find the pin fine. Scratched my head and went for a swim .. no prop. The yard that serviced the thruster zinc didn't tighten the nut.

[tshug]

Rob, thanks for the reply and replacement steps. What is the size of the Mercruiser "Quicksilver" pins? Are they 3mm or 4mm?



Kevin, I went for a swim yesterday and the prop was still there and I could still turn it with my hand. I think it is the shear pin.

[Paddy]

Not sure of the size, take the thruster off and bring the end piece and remaining piece of pin to the marine store, they can size it up for you. Just checked my marine store's catalog, they only had one listing for the mercruiser shear pin, but it was the exact same demensions as the vetus one.

Good luck

[special k]

there is also a shear pin behind the prop and zinc if the one at the motor is intact, but that would require hauling or a diver.

[mike66]

If you're really pressed for time and can't find a shear pin, a small nail cut off to size will get you through, although without the protection. Now I carry spare Vetus pins sourced through Jamestown Distributers. Paddy, great write up of the replacement procedure.

[Tree]

The one you can access is 3mm IIRC and the one on the propeller is 5mm diameter.

Both made from Naval Brass, personally I would stick with the correct material so that if it should need to shear again then you will not be overloading or underloading the part that is supposed to break.

[RobS]

I bought a set from Vetus back in 2007 when I bought T-R and never needed them. They were down deep in one of my tool bags but I was able to find them and leave them for the new owner. I did use the thruster all the time though as my slip is a port side approach which is a PITA without the thruster, unless I opted to do a 270 degree starboard walk rotation. I think a lot has to do with the user, no left-right-left, pause a moment between direction changes and keep the growth off the prop.

[tshug]

Paddy, thanks again for the great write up! I took the thruster motor out today following all your steps and it came out without any problems. The interlocking drive end did fall to the bottom of the thruster and I found the shear pin broken into three pieces. I'll check with the local marine marine stores around here tomorrow for the replacement.

[Paddy]

Good to hear, hopefully, they can hook you up with the right replacement. The aluminum pins sold to me are for 3hp plastic prop outboards, so I have to assume they have a similar level of "let go" as the Vetus bronze, but not as pricey. FYI, I went to a reputable marine store, not West Marine, not sure if a chain store will have the part in stock.

Good luck

[tshug]

I found the same size diameter brass shear pins at a local shop here. They were a little longer and I had to cut them down, but they fit. Got the thruster back together today and it's back working again!!

Thanks for all the responses and I hope everyone has a great 4th.

[Pitou]

Good job Capt.. Way to learn your boat and get it done! Docking will be a pleasure again.

Cheers!