2004 Mainship 400 bow thruster breaker

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Blue Tortuga

Veteran Member
Joined
Feb 23, 2018
Messages
73
Location
USA
Vessel Name
Goodnight Gracie
Vessel Make
Mainship 430
Does anybody have an idea where the bow thruster breaker is on a 2004 Main ship 40 single diesel trawler. Normally you find a big breaker somewhere up by the thruster but on this boat I can’t find it anywhere. Not up and about and not in the engine room by the battery switches or by the lower helm.
It doesn’t appear in the manual either so I’m hoping someone knows where it is. Thanks
 
The last 400 I looked at I could not find it either. On a 390 it was inside the cabinet where the electric panel is mounted. The spot it was located in required removal of screws to get to it.
 
Fuse found

To who else needs to know.
So typical, the fuse for the thruster was inside the electrical panel in the engine room. Like that a great place to hide it!
 
To who else needs to know.
So typical, the fuse for the thruster was inside the electrical panel in the engine room. Like that a great place to hide it!

It has to be there, for safety reasons. The longer the length of an unprotected conductor, the greater the chance of fire if there is a short circuit or overload.


Understanding the rules can help you find these devices easily.

Except for engine cranking, ABYC requires the overcurrent device to be as close to the source of current as possible according to the '7/40/72' inch rule. For un-enclosed wiring connected directly to a battery, it's seven inches. If the wiring is directly connected to the battery but is 'fully enclosed along it's entire length' for protection from accidental damage, the overcurrent device must be within 72 inches.

For thrusters, the wire normally comes from the main battery switch and in this case the overcurrent device must be "as close as possible, but not more than 40 inches" from the switch. So...look for the battery switch and you will find the fuse within 40 inches, usually much closer, because the rule says "as close as possible".

In our MS390, it is right next to the main battery switch, maybe 10 inches downstream.
 
I also have A Mainship 34. I thought my bow thruster popped the breaker. Couldn't find it either. BUT! I also, just for giggle's, I tried the lower station bow thruster switch and it worked. The upper station switch was shot. I changed the upper with the lower and ordered a new switch. $238!!! Hopefully you will find the breaker and that will work, but check the lower station first.
It is in the engine room, I found it last time I was crawling around down there.
 
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