circuit breaker for trolling motor

rwidman

Lieutenant
Joined
May 27, 2004
Messages
1,396
Re: circuit breaker for trolling motor

Folks, there is no good reason to re-engineer your boat's wiring system or the recommendations of the manufacturers. The good folks at the ABYC have already considered everything presented here and more. They are engineers, safety experts, and testing professionals. Most of us are not.

If the manufacturer recommends a 60 amp circuit breaker for his motor, that is what you should install (according to ABYC code). If a manufacturer recommends a 7 amp fuse for his bilge pump, that is what you should install (again, according to ABYC code). Use only "marine" rated parts from a reliable manufacturer, and if you don't know how to do it correctly, hire a pro.

Then go boating.
 

roncoop75

Petty Officer 1st Class
Joined
Jun 23, 2010
Messages
229
Re: circuit breaker for trolling motor

Folks, there is no good reason to re-engineer your boat's wiring system or the recommendations of the manufacturers. The good folks at the ABYC have already considered everything presented here and more. They are engineers, safety experts, and testing professionals. Most of us are not.

If the manufacturer recommends a 60 amp circuit breaker for his motor, that is what you should install (according to ABYC code). If a manufacturer recommends a 7 amp fuse for his bilge pump, that is what you should install (again, according to ABYC code). Use only "marine" rated parts from a reliable manufacturer, and if you don't know how to do it correctly, hire a pro.

Then go boating.

For those that are curious, the reason a 60A is suggested with only a 40 draw is because it's common engineering practice to rate breakers/fuses at 50% over max load. I've been in the electronics field for about 20 years now and it's fairly common to see this. In all our comm sites, if you're putting something in the rack that will draw 20A you breaker it for 30A. Total site load is 100A, breaker it for 150 ect. These are all DC (24V or 48V) sites BTW.

A 60A breaker for a 40A load looks completely normal to me.
 

rwidman

Lieutenant
Joined
May 27, 2004
Messages
1,396
Re: circuit breaker for trolling motor

For those that are curious, the reason a 60A is suggested with only a 40 draw is because it's common engineering practice to rate breakers/fuses at 50% over max load. I've been in the electronics field for about 20 years now and it's fairly common to see this. In all our comm sites, if you're putting something in the rack that will draw 20A you breaker it for 30A. Total site load is 100A, breaker it for 150 ect. These are all DC (24V or 48V) sites BTW. .

Keeping in mnid that the breaker capacity must never be higher than the current carrying capacity of the circuit supplying current to the load.
 

RicMic

Chief Petty Officer
Joined
May 14, 2010
Messages
431
Re: circuit breaker for trolling motor

"I happen to also be a fan of lawn darts by the way and they by themselves were not dangerous. The idiots that used them carelessly were dangerous."
I agree absolutely, thats why things are designed(or should be) to be "idiot" proof. A case could be made for putting automatic reset circuit breakers on things like bilge pumps, which are extremely unlikely to be "dangerous", however personally, if there is a problem in my boat, I want to know about it and make the decision on correcting it, not a few cents worth of metal and plastic. For instance, someone notices that their trolling motor has stopped, they hit the throttle up a few times and nothing happens, they tip it up and find fishing line wrapped around the prop, so they get out the sharp knife, grab the prop and start cutting RESET. A guy is out fishing alone and his motor stops, he bumps the throttle a couple times and nothing happens, he get up and leans over the bow, can't see anything so he turns the motor 90 degrees by hand, that clears the piece of wood wedged between the prop and skeg, RESET the motor now restarts at 100% and at 90 degrees to the stem of the boat, the guy finds himself in the water with the boat running flat out in circles, maybe it hits him, maybe he swims out of the way and watches the boat troll off into the distance, all we know is that the boat is found some hours later with the motor at 100% and the battery dead. The only witness is never found, so some of this is a guess, but its what COULD have happened. If you want to call these scenarios "dangerous", then I wouldn't argue with that.
 
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