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carlager 09-20-2013 10:14 AM

Bow Thruster problem
We have a Lewnar 185tt bowthruster in our Beneteau Oceanis 36cc. The thrust has suddenly become poor, is hardly able to push to either side and motor is having a " new" sound.

What I have checked so far is

1. Voltage on motor (13V when idle and 10V when running)
2. Propeller for debris ( no debris, all blades are intact and the propeller is easily turned by hand)
3. Brushes (managed to get one out of the housing. It had required length and was in ok shape)

Anybody with similar experiences and/or an idea of what can be wrong

Minnewaska 09-20-2013 02:08 PM

Re: Bow Thruster problem
Drop in voltage could mean corroded contacts somewhere. Start at the thruster and work your way back to the panel.

hellosailor 09-20-2013 02:58 PM

Re: Bow Thruster problem
If you can physically drag a good battery and a set of jumper cables forward, one fast way to check things would be to be do just that. If the thruster spins up just fine, then you know there is a problem in the wiring. If it still is sluggish, that would point to an internal problem.

I've no idea what the voltage should run under load but I suspect 10V is way too low and that indicates a corroded connection somewhere between the thruster and the main batteries. Even a starter motor doesn't normally pull voltage down that low.

13V at idle is also low, a good alternator will be putting out 13.8-14.4 volts in most cases, and at idle with nothing engaged, you should see almost all of that even at the thruster. Another sign of a contact/wiring problem, check right at the batteries to see what the real drop is from "there" to "there".

carlager 09-20-2013 03:43 PM

Bow Thruster problem
Interesting. The voltage is measured on the connections on the motor (i.e 13V idle and 10V loaded). Is that low ? (the thrusther is 12V)

deniseO30 09-20-2013 03:51 PM

Re: Bow Thruster problem
check the contacts of the controller.. if it's not sealed. corrosion will drop the voltage dramatically and the contacts will even heat up.

hellosailor 09-20-2013 08:14 PM

Re: Bow Thruster problem
A nominal "12" volt system is 14.4 volts when an alternator is running in bulk mode and about 12.6 volts for a fully charged new battery. "12" volts would actually be a system running at more than 50% discharged battery power, so yes, "12" is low.

carlager 09-21-2013 06:25 AM

Bow Thruster problem
Voltage drops from 13,3V to 12,3V on the connections on the dedicated battery and from 13,3V to around 10V on the connections on the bowthrusters motor. Would this indicate problems with the battery or wiring ?

Minnewaska 09-21-2013 09:28 AM

Re: Bow Thruster problem
I say wiring. There should be a breaker and/or fuse between the two where connections could be corroded. Ground (or neg side in DC) is often the culprit, as they are often on bus bars or use other common grounds. Perhaps not on a dedicated battery. Still, as I said above, you should track down and clean every single connection. The corrosion is typically noticeable, but not always. I could be hidden below a ring connector, allowing voltage to pass when there is no load, but increased amperage caused the connection to microscopically separate.

carlager 09-21-2013 10:53 AM

Bow Thruster problem
Thanx a lot for your suggestions. I will track down and clean all connections

carlager 09-24-2013 03:18 PM

Bow Thruster problem
Uninstalled the motor and discovered that the drive pin was broken. Installed a new and the thruster works again

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