Bow Thruster Woes

[Dockhead]

Last weekend I checked the oil in my Sleipner 10hp bow thruster and found the plastic oil reservoir slightly overfilled and leaking out.

Sigh. I presume that means that the seals are bad on the drive leg, which is letting in sea water, which is displacing the oil. A death sentence for the drive leg if not quickly dealt with, I presume, since my boat lives in the water year around.

Anyone have this problem? Can the seals be just popped in, or does it require major surgery? I will have the boat out of the water for a couple of hours on Friday for her quarterly scrub-off -- is it anything I could deal with then?

As always I would be grateful for knowledge-sharing.

[dwhatty]

Have a somewhat similar problem with ours (same brand, but SP55s model) except that the oil was draining out of the reservoir into the bilge at the motor end. First fix attempt was to replace the shaft seal on the gear leg shaft, which is the only thing that can be done with the boat in the water. A bit of a pain, but not too bad if you have access, involving taking the motor off and the using a pick of some sort to get the old seal out and an appropriate size socket to seat a new one.

In my case, a new shaft seal worked for awhile but the leak returned. Also, had a bit of seawater leaking into the bilge past the gearleg to hull gasket.

After hauling for the season, I removed the gearleg from the boat (motor had to come off again, then the prop, then the motor mount and gearleg). The motor removal is the pita part, but gearleg removal was very easy. If you have new "O" rings, shaft seal, mounting gasket and caulk on hand, and remove the motor beforehand, you probably could get the job done in a couple of hours haulout. I am told that the critical part in remounting the gearleg is to ensure that it is centered in the tunnel when/as the two motor mount to gearleg bolts are tightened and that no caulk gets into the threaded bolt holes. Use tongue depressors wedged between the ends of the prop blades and the tunnel for centering.

Inspection of our gearleg showed several things: that there was water in the oil, that the shaft where the shaft seal is was corroded a bit probably causing the seal failure, that the two shaft "O" rings in the motor mount were worn allowing water to seep by and that all of this was all almost certainly caused by an installer who did not caulk both sides of the gearleg to hull gasket. He used no caulk between the gasket and the hull.

IMTRA has the gearleg and I am waiting on the verdict as to whether it is beyond repair or not. (i.e. If they can smooth out the corroded shaft to tolerances or not and whether there is any internal damage or not). A new gearleg is almost a "boat buck" and used ones are almost unobtaniuim. Gearlegs evidently cannot be taken apart and worn internal parts replaced.

Mark Raeder at IMTRA has been very helpful throughout. IMTRA has given me excellent advice and customer service (including on a previous stern thruster problem I had) even though the thrusters were not purchased through them.

[GordMay]

"Side-Power" (by Sleipner Motor) thruster manuals:
➥ Side-Power bow & stern thrusters - Manuals

[Dockhead]

Wow, thanks for the incredibly helpful information, dwhatty.

The liftout overnight, requested by the Sleipner agents, will cost me 800 pounds ($1300 -- ouch!) so it seems hardly worthwhile just to find out whether I need a new drive leg (1100 pounds - ouch! ouch!). I think I'll buy the seal set and take my chances. If the drive leg is bad, then it won't do any further harm to be in the water for a couple months more before changing out the leg.

[dwhatty]

Good luck.

[sunvale1]

I happy for you fellows with enough information on you thrusters that allows you to get parts. I spend the past week just garnering information on my Side Power 3 bladed system to purchase the right parts. The unit dates back to 1989-90 and the company in England is reluctant to give me any idea as to what parts I need to make mine work again. I think I would prefer to look for the needle in the haystack.

[dwhatty]

Originally Posted by sunvale1

I happy for you fellows with enough information on you thrusters that allows you to get parts. I spend the past week just garnering information on my Side Power 3 bladed system to purchase the right parts. The unit dates back to 1989-90 and the company in England is reluctant to give me any idea as to what parts I need to make mine work again. I think I would prefer to look for the needle in the haystack.

Don't know where you are located, but if in USA talk to Mark Raeder at IMTRA.

[sunvale1]

thanks dwhatty. I spoke with somebody there and they will get back with me with the information I need. I also spoke with Skipper Buds and a handful of others. Just like to get the boat pulled, the prop on it and finish the season without any more mishaps.