Bow thruster ran amok after a close lightning strike...

[Sailshabby]

We’ve got a SidePower 80 bow thruster. Just had a lightning strike close enough to shred some “upper gear” on a boat about 50’ away. Our little home survived with the exception of the bow thruster, which decided to take off on its own. Only way to shut it down was with its ON/OFF master switch. Gave it 30 minutes, turned it back on, and we were again off to the races. As noted, nothing else appears to be damaged.

My suspicion is somehow the cockpit control panel fried, but I thought I’d throw the question out there. I’ll be doing some troubleshooting once the storm passes and the sun returns.

Thanks.

[1affiah]

My guess would be the solenoid contacts welded shut.

[Sailshabby]

Thanks. I actually had that thought, but it was outweighed by nothing else on the boat taking a hit (logic being if there was enough juice to do some welding...). Now I’m wondering if the zap came through the water and up through the motor.

[Capt Clark]

Originally Posted by 1affiah

My guess would be the solenoid contacts welded shut.

I’m with 1affiah. If it’s an electric thruster, it’s easy to check with a multimeter. A little different if it’s hydraulic.

Capt Clark

[SV Bacchus]

Originally Posted by Sailshabby

Thanks. I actually had that thought, but it was outweighed by nothing else on the boat taking a hit (logic being if there was enough juice to do some welding...).

Having had a lightening strike two years ago I would say it is possible you have more gremlins lurking about you haven't discovered yet. Some show up 6 months later but admittedly that is for a direct hit.

It may be little things, a light here, a fan there, thermostats not quite right, etc..

[Marc13]

1306/5000

We had the bow thruster which did not stop after being drowned in very bad weather, because a wave opened the closing levers of the hood of the sail compartment. We then anchored to repair before returning to port. The electronic card did not work any more and controlled all the time the relay of the engine which always turned. We disconnected the + wires from the two relays. After rinsing the electric motor for a long time with fresh water, we dried it a little before checking that it was working properly. Once in the port with 40 knots of wind, it was my son who controlled the relays directly with a wire.
Since then, we have added an emergency control box with two 3-position change-over switches and by adding 3 diodes. The first inverter is used to completely cut off the power in bad weather, or to use the electronic remote control or to use the emergency control. The second is used in emergency control to activate the thruster in either direction.
It is prudent to have such an emergency circuit if you wish to have the propellant usable in the event of failure of the electronics, which happens with lightning but also in the event of water entering the bow thruster compartment