More bow thruster issues

T

TimHenn

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For the second time in a matter of a couple years I've managed to lose my bow thruster prop. Not from using it, from running in offshore seas.

This time it appears it not just a prop replacement but instead the shaft itself is damaged. I had a diver attempt to replace the prop but he says there is (no longer) any threads on the end of the shaft. Gonna have to short haul it but I want to make sure I have the parts to do this.

Take a look at this, if interestedhttp://great-water.com/store/PDF/files/parts_diagram_list/CT-900_Parts.pdf

#11 is the shaft itself. Does anyone have experience replacing a shaft like this? Can this be done reaching through the bow thruster canal or is this something where the whole unit has to be removed (that would suck). I'm assuming I need a new seal kit and the shaft, and ?? Not sure about the other parts.

I love my Volvo engines but getting Volvo on the phone to have this conversation seems difficult if not impossible. If anyone has a Volvo name and number I would gladly give that a try.
 
When I bought my previous boat it had thread loss due to electrolysis. I found this out during the first bottom painting

It was a SidePower. The zincs were small and not carried by WM so they were neglected.

It required a new shaft from SidePower. At that time new seals were installed. The mechanic said that it was not that hard a job.

Don't see how it could be done in the water, but maybe possible. You need to talk to the mfg.
 
Tim, some of the owners club members have discussed Volvo thrusters and parts and so forth...

-Chris
 
Thanks Chris, I keep meaning to join the owners club (again) and never get to it...and I always hesitate as the season starts to close.

Electrolysis is a valid explanation. The boat was stored in-water last winter so the zincs did not get replaced on the thruster (forgot about that). Next spring I'll have the divers do both the running gear and the thruster zinc.

Tim
 
ok, broke down and joined the SOC one more time. Hopefully theres some answers over there
 
I'm told the threaded piece on the end of the shaft is a stainless steel 8MM stud that Volvo has confirmed can spin out and then you loose your bow thruster prop. This is good news because the parts to replace the shaft were pretty high not to mention the likely long haul $$ to do the repair.

Volvo recommends replacing the stud using Blue Loctite thread locker. Anyone know if this can be done in the water? Could the diver apply the thread locker to the stud out of the water, dive and screw it in? I can't seem to find much that says you can or can't do this.
 
No you cant apply thread locker underwater. The threads need to be clean and dry.

Now you could apply some underwater setting epoxy to the threads of the nut topside and then hope some of that fills the gaps between the threads a bit and sets up. I have also seen nuts that have what looks like blue thread locker pre-applied and setup on some of there threads. So I guess you could try that and hope for the best.
 
That makes no sense to me an admitted novice. Could you not use never seize and back 2 nuts against one another? It would seem to me a lot could be done underwater with that method. Then again, I'm hitting in from the outfield on this one.
 
LOCTITE® Anaerobic Adhesives

Anaerobic adhesives work by completely filling gaps between metal components. Using an anaerobic adhesive prevents loosening from vibration and also protects the joint from corrosion or rust that can result from moisture. They are typically used to augment the seal or holding force of a mechanically joined assembly. Loctite® Anaerobic Adhesives include threadlockers, thread sealants, retaining materials, and gasket sealants.

Anaerobic sealants cure in the absence of air, so I guess if you can keep it on the stud under water it should work.

Rich
 
quote:
Originally posted by KiDa

That makes no sense to me an admitted novice. Could you not use never seize and back 2 nuts against one another? It would seem to me a lot could be done underwater with that method. Then again, I'm hitting in from the outfield on this one.

Click to expand...


You wouldn't want to use true Never Seize because of dissimilar metal issues. And two nuts might work but perhaps not if the system is not set up for it.
 
I don't believe Loctite will work underwater.

But there are two easy ways to find out. Ask Loctite.

Or put a bolt underwater in your sink, coat the treads of a nut out of the water, screw them together underwater, let them sit in the water over night and then see how easily they come apart the next day. :-)
 
I don't have a bow thruster but I always jump in & replace 6 my U/W zincs 1 to 2 times during the NE season . Just did that in the last week after the anodes were replaced last before spring commissoning. The only thruster prop shaft issues (loss of prop, broken shaft)I have heard of involved lack of timely anode replacement,... but that doesn't mean that was the case with yours.
 
FWIW, I happened to be in a NAPA store yesterday and the first line on the instructions on the back of the tube of blue Permatex thread locker stated the parts need to be clean and dry before assembly.
 
before calling the repair done you may want to have a galvanic survey done. if the threads are gone on the end of the shaft i'm betting there is corrosion at work.
 
How about just learning how to handle the boat. Good boaters don't need a thruster with a boat that size, they know how to handle it. Saw the other day in my marina a guy tries to dock his 45ft. boat, thruster running all the time, crash. Saw a guy minutes later, 48ft. no thruster docking no problem.
 
Well there is that. But since he probably can dock his boat without a thruster but has one any way, he might as well fix it don't you think?
 
I agree Capt Bill,
I have the same boat and lost the thruster middle of the season last year, I waited to the winter haul to fix it (broken blades on the prop). The thruster is rarely used, but does come in handy at times. Having something on the boat that is broken urks me, bet Tim feels the same.
 
I use a product called Vibra-Tite on the threads for all my zincs. Seems to work well, and the screws/nuts/bolts are easy to remove when it comes time to replace the zincs for the next season.
It may work for the threads you are talking about on your bow thruster too.
 
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