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Troubleshooting
Bow thruster won’t turn off? Kill the main switch, then read this
You let go of the joystick and the thruster keeps pushing. This page shows you how to stop it, how to tell a documented feature from a real fault, and what to tell the electrician. These motors are built to run in short bursts, so act first and read after.
Is it running right now? Go to the battery main switch and shut it off. Read the rest after.
At the stern. A stern tunnel thruster is the same kind of unit as a bow one, and 61 of the 140 tunnel models this site lists are sold for either end. So it is covered by the steps on this page. The units made only for the stern are external, from Max Power, Sideshift, Sleipner Side-Power, Yacht Thruster and ezDrive, and the sections below on the other kinds cover the Sideshift and DockStar ones.
The short answer
That switch sits between the battery and whatever might be stuck. Do not experiment with the joystick or the panel first.
On panels that have it, HOLD keeps a chosen thrust running after you let go. If you did not know the feature was there, you can mistake it for a fault.
VETUS rates its DC BOW PRO motors for about ten minutes of continuous use at full current draw. A motor stuck on keeps pulling that current the whole time.
It could be a welded contact in the panel, a relay or solenoid stuck closed, or chafed wiring. A marine electrician with a meter can tell you which.
Stop it and find the cause in four steps
- Shut off the battery main switch. Do this before anything else. The section Do this first explains why the panel cannot be trusted to stop it.
- Check whether HOLD is on. Once the boat is safe, rule out the one cause that needs no tools. The HOLD section lists the three ways to cancel it.
- Write down what you saw. Note whether it started after an install or a repair, and whether one panel or both are affected. The section Once the power is off says what each answer points to.
- Call a marine electrician. If it is not HOLD, a part between the joystick and the motor is stuck on. The section on what is stuck lists the likely parts.
Do this first
Kill it at the battery main switch.
The makers’ manuals tell you to shut the main switch off whenever the boat is left unattended. This is the kind of fault that instruction is there for.
The The heavy switch, usually near the batteries, that disconnects the thruster from its battery entirely. It is the only switch that stops a motor that has stuck on. is the one control in the whole circuit that sits between the battery and whatever might be stuck. If the fault is in the panel or the joystick itself, you cannot rely on the panel to stop it.
Then check: is HOLD engaged?
Once the boat is safe, check whether this is a fault at all.
Some panels have a HOLD function. You choose a thrust level, then press the button on top of the joystick. That thrust locks in and keeps running after you let go. It is a feature the manual describes, for when you need push for longer than you want to hold the stick over.
Three things cancel HOLD:
- pressing that same HOLD button again
- moving the joystick in the opposite direction
- switching the panel off from another panel, if the boat has one
If you have never used the feature, or bumped it by accident, a thruster on HOLD can look like a stuck one. Rule it out first. It is the one explanation on this page that needs no tools and no electrician.
External and retractable units: where the off switch is
HOLD is a VETUS feature. The other kinds have their own version of a thruster that keeps running, and their own way to stop it.
- A Sideshift external unit has a battery switch of its own, and its manual says to turn it off before any work near the thruster. That is the kill. The joystick switches itself off after twenty minutes unused, which is not the same thing. The timer will not stop a unit that is running on. The switch will.
- A DockStar pod runs on by design from the outer buttons on its remote: they latch, and the motors keep turning for thirty seconds after the last press. To stop it early, press either inner button (they run only while held). If it keeps running with no button held, the faceplate has a mechanical ON/OFF switch, and lifting the unit off its track cuts the motors, since a sensor lets them run only when fully lowered. Its user manual (v.260305) is linked from the DockStar review.
- A retractable’s motor is fed through the same battery main switch as a tunnel unit’s, so that switch is the kill, exactly as above. Lewmar’s retractable manual adds a useful tell. Its panel will not power up while a port or starboard signal is present; it goes solid red instead. So a thruster that would have started the moment the panel came on is a stuck joystick or a wiring fault, and the panel has already told you. It also stops thrusting if it receives both directions at once.
Why this one is urgent
Bow thruster motors are built for short, hard bursts, unlike a bilge pump or a fridge compressor. VETUS rates its DC BOW PRO motors for about ten minutes of continuous use at full current draw, or a similar total per hour. That figure is the motor's How long a motor may run before it must rest, as the maker rates it. "2 to 3 minutes" means that long at full power, then a pause to cool down..
The duty cycle describes normal use, where the motor rests between bursts. A motor stuck running is not resting. It pulls that same high current the whole time.
The thruster has its own protection against overheating in normal use. That protection is designed around the motor cycling on and off under the joystick's control. A fault that bypasses the joystick, in the relay or the wiring, is another matter. This page cannot promise the protection catches it.
Because nobody can promise the motor will protect itself, kill the power at the main switch instead of waiting to see.
If it is not HOLD, something is stuck on
A joystick is a momentary switch, which means it works only while you hold it. It sends thrust while the stick is over, and nothing once it is centered.
So if the motor keeps running with the joystick centered and HOLD off, something between the joystick and the motor is stuck in the "on" position. There are a handful of ways that happens. None of them can be diagnosed from a description.
A contact welded shut inside the panel or joystick itself, from age, corrosion, or years of switching current.
A relay or An electrical switch worked by a small current that closes a large one. In a thruster it connects the battery to the motor when you press the joystick, and it is a common part to fail. Solenoid, relay and contactor are three names for this one part. stuck closed in the control circuit between the panel and the motor. That part is not the panel you are looking at, so the panel itself may be fine.
Chafed wiring that leaves the trigger wire permanently live. VETUS's own installation guide warns that wiring routed against the circuit board can lead to malfunctions. The problem starts at installation and shows up much later.
None of these is a job for guesswork. Each one is a job for a marine electrician with a meter and the wiring diagram for your panel.
Once the power is off
With the main switch safely off, note a few things before you call anyone. They will shorten the conversation.
Was HOLD engaged? Before you assume a fault, check the panel's own indicator for it. Do that once you are ready to bring power back, cautiously.
Did it start right after an install or a repair? Freshly disturbed wiring is the most likely culprit. Whoever installed or serviced it should hear about it before a new electrician does.
Is only one panel affected, on a boat with two? That points at the panel or its wiring more than at the motor controller, which both panels share.
What not to do
Do not keep working the joystick the other way in the hope it cancels whatever is stuck. If the fault is past the joystick, in a relay or the wiring, the joystick has no way to override it.
Do not leave it running to see if it stops on its own. A motor rated for ten minutes of continuous use does not get safer the longer it runs past that number. It will not necessarily warn you before something gives.
Once the power is off and the fault is found, it may turn out to be in the thruster itself. If so, compare a repair against what a replacement costs installed, especially on an older unit.