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Box thruster repair in water?

Jun 15, 2012
Hunter 50 AC St. Petersburg
The "hub" or gearbox installed in my Hunter 41DS needs replacement. It is a Lewmar 140TT part # 581001. I am wondering if it would be possible to dam up the starboard side of the tunnel, and then tip the boat over with the halyard enough to get the port end of the tunnel out of the water. The tunnel is located just below the water line so the boat would only have to be "tipped" up on the port side maybe 10-12".I am thinking of doing this while the boat is at a dock, using a dock piling as an anchor for the halyard. I am still in the thinking stage, any thoughts would be appreciated.


Jan 5, 2017
Beneteau First 38 Lyall Harbour Saturna Island
Any tidal-grids in your area? I think what you propose would make the work very awkward. I know I would drop something important that would be lost forever.
Jun 15, 2012
Hunter 50 AC St. Petersburg
Boat is in Florida, I don't think there are any tidal-grids nearby as tidal variation is around 2 feet.


Jun 4, 2009
Pearson 530 Admiralty Bay, Bequia SVG
Considering all the things that could go wrong in trying to do this on the cheap and the expenses which this might incur, I'd be more apt to go for a haul out. Also, the possibility that this project may require a bit more time than you expect, and don't they all, then what would your plan be for this taking a day or two?


Oct 21, 2009
hunter 38 Monaco
Make a cover for both sides of the tunnel. Tension with a connection wire through the tunnel and through the covers. Tighten. Open the tunnel for the replacement. Even if you have water getting past the covers it will be minimal. You have all the time for the intervention, no stress because of tides and other. Good luck.
Jan 7, 2011
Oday 322 East Chicago, IN
It sounds to me like he has to have at least 1 side of the tunnel open, plus the mount hole, to affect the repair. So I don’t think he can keep the covers over both sides of the tunnel.

I think I would opt for the haulout, fix the bow thruster and any other maintenance needed and splash her back in the water.



Jan 15, 2006
Macgregor 22 Silverton
Cover the other side of the thrust tube so it won't leak. Get a 5 gallon bucket cut part of one side out of it so that you can tape it up next to the other side of the thrush tube. It will be awkward to reach in from the top of the paint bucket to get to the hub but it should be doable without hauling the boat or even tipping it with the halyard. It shouldn't take long to shop-vac your temporary dam to see if it's leaking or not then go about fixing the thruster.