Lewmar Bow thruster energizing by itself

drfeno

Member
Joined
Jun 19, 2008
RO Number
30284
Messages
133
I have a Lewmar TT 185 bow thruster that is about 5 years old. the other day someone from my yacht club calls me and tells me my thruster is going off by itself and pushing my boat into the one along side me. I asked him to go aboard and turn the battery switch under the front berth off. WTF. I did a search and found out that this is a known issue with these thrusters and they usually blame water intrusion into the joystick assembly. My joystick is in a pilothouse, and never gets a drop of water on it. When I got down there to check it out, the battery had been recharged due to being on shore power, but when I (hesitantly) tested it, as soon as I "armed" the joystick the thruster started to run. I tried calling Lewmar but the tech support guys were at a boat show. Even the tech support fill in person knew about the issue, and she spouted that I should always turn off the battery switch when I'm not there as per the manual. Sure, but lets not pretend that this is OK. I'm going to call the regular tech guys on Tuesday to find out if I have any recourse (probably not). Has anyone had this issue, and had Lewmar do the right thing?
 
You are in a marine environment, if it is salt even worse. Contacts corrode and sometimes corrode to the point they "bridge over". This is highly dangerous as usually this is usually a high resistance contact which results in an over heat of the switch and possible fire. This is why you turn your batteries off when unattended. The best way to prevent this is to maintain your electrical system with dielectric greases and protectants. I am willing to bet a good cleaning of the switch with contract cleaner and WD-40 will restore functionality.
 
Please post what you find

To activate the thruster, your joy stick closes a low voltage circuit to a solenoid that allows high current to power the thruster.
Your problem could be one of the following:
Bad joystick ( to determine if that is the problem, disconnect the joystick and see if you have the problem)
Bad connection (corrosion on a connector from the joystick to the solenoid on the thruster) The corrosion, if that is the case would have to be so bad it is actually making a connection to engage the solenoid.
Pinched or bad wire from the joystick to the solenoid.
Bad Solenoid
If there is a electronic controller that the joystick signals to activate the solenoid, that could also be the problem.
I would have Lewmar send you a schematic on how this all works and how it is wired and how the joystick activates the thruster.

Good luck and let us know what you find

Walter
 
Thanks for the replies,

The joystick unit itself is sealed, and not open to maintenance. It connects to the thruster via a proprietary cable that has plugs at both ends, all are high and dry and corrosion free. I've been in contact with Lewmar and they've said they'll do the right thing and replace my joystick assembly. I have done some tests that pretty much show its the joystick at fault(disconnecting the connectors and turning on the battery switches). This is a known issue for them. My boat is kept in a river, but we see salt water 5 or 6 times a year. The joystick is in a pilothouse, and is completely dry all the time. I understand its in a marine environment, but this is an expensive unit that I would expect to last longer than 4 or 5 years. Anyway, we'll see if they come through. I don't need them to install it or anything, it would probably take me 10 minutes at most. It is nice to see that a company like Lewmar will stand behind their products when they know there's a flaw.

Dave
 
Dave,
I had a Lewnmar thruster installed on a 34C Silverton many years ago. Old boat I had that I know longer have. Yes they were great, to deal with and other than a shear pin problem, the thruster served me well for the 5 or 6 years I had the boat. When I needed the shear pin, they sent me 2 at no charge. Glad to see you solved the problem.
 
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