Main Fuse on Battery

[TomW1]

Orange Quest is correct. The main breaker of 150-200 amps must be betwenn the battery and the motor. Then on the battery there is a second post going to the console thet you fuse or breaker with the proper size for all the items you have in your fzze or breakerrs. Each item will have there own breaker/fuse, some will come with them some will require an inline fuse added to the line. Here is a copy of a marine battery from West Marine. https://www.westmarine.com/buy/west-mar ... ecordNum=2 Most fish finders have there own fuse but check your owners manual they may require an inline fuze also. Guages also require a small fuze. Any theng electrical usually requires a fuze. If you install a battery and trolling motor forward it will require a lager fuze/breaker.

If you have any questions please ask.

Tom

[fallguy1000]

Starters are not fused.

What protects against a short on the starter cables? Or is it just assumed that you must make sure that this would never ever happen?

The assumption is that a fuse might blow rendering you bobbing at sea.

The next assumption is that guys won't crank on the starter for 30 minutes.

If you insist on cable protection, a resettable breaker with thermal protection is probably a good solution.

[fallguy1000]

I just looked at a couple production center consoles with starting bats in console/under leaning post. All had 200hp (or larger) motors. All used 200a BREAKERS.

I checked a couple sailboats because … I can. All the “new” boats had breakers. All the old boats were directly wired. All were diesel. Perkins, westerbeak, yanmar and the Mercedes block that never wants to run.

If it were me. Breaker sized to prevent burn of wiring. Get the “slow” trip type. I think that’s what FG1k mentions.

The 200amp fuse are typically Class T which are the first fuse to all house loads on the house bank. Sometimes @24v or more.

I would be very surprised if anyone class T fuse protects the starting circuit on the big engines. Some of those starters are really big and would easily pull close
To 200a.

I won't be fusing my starter wires. And ABYC does not require it.

[fallguy1000]

Here is a good page from a highly reputable US electrical consultant,

https://shop.pkys.com/Overcurrent-Protection_b_12.html

And a cutaway on starters highlighted here.

[jonnymac]

There two different situations the wire going from the battery to the starter can have problems. one is during starting when starting current is running through it. a properly sized wire is going to be fine because either the starter will die or the battery will run out if juice before you really need to worry about the wire.

the second is when its just sitting there with battery voltage applied with the full potential of the battery available for damage through that thick cable. this is the situation you would want a fuse or breaker. when you aren’t on the boat or paying attention and there is a problem. a fuse or breaker keeps your boat from burning down. a battery disconnect switch might be a better option here as you get all the protection, and better reliability.

[fallguy1000]

There two different situations the wire going from the battery to the starter can have problems. one is during starting when starting current is running through it. a properly sized wire is going to be fine because either the starter will die or the battery will run out if juice before you really need to worry about the wire.

the second is when its just sitting there with battery voltage applied with the full potential of the battery available for damage through that thick cable. this is the situation you would want a fuse or breaker. when you aren’t on the boat or paying attention and there is a problem. a fuse or breaker keeps your boat from burning down. a battery disconnect switch might be a better option here as you get all the protection, and better reliability.

I have four remotes on the Skoota and one ACR. ACR instructions say, do not fuse! Basically, it'd be like fusing jumper cables.

The other thing about the remotes is you can hide them a bit AND lock them out so they cannot be remotely triggered. So a wpuld be thief tries to flip the remote switch and it fails. Then he decides to seek the remote if he is smart enough to even anticipate it is being used as a lockout device, and that takes considerable time to hunt or trace starter wires. My starter remotes are behind locked doors, so first they have to break open the doors.

[fallguy1000]

Another diy boater wiring tip. No wires below 16 gauge are allowed. The device pigtails may be below 16 gauge, but no boat wiring can be...

[jonnymac]

once again, jumper cables don’t need protection because you are standing there when they are in use. be careful with that analogy.

remote what? and what does ACR stand for?

There two different situations the wire going from the battery to the starter can have problems. one is during starting when starting current is running through it. a properly sized wire is going to be fine because either the starter will die or the battery will run out if juice before you really need to worry about the wire.

the second is when its just sitting there with battery voltage applied with the full potential of the battery available for damage through that thick cable. this is the situation you would want a fuse or breaker. when you aren’t on the boat or paying attention and there is a problem. a fuse or breaker keeps your boat from burning down. a battery disconnect switch might be a better option here as you get all the protection, and better reliability.

I have four remotes on the Skoota and one ACR. ACR instructions say, do not fuse! Basically, it'd be like fusing jumper cables.

The other thing about the remotes is you can hide them a bit AND lock them out so they cannot be remotely triggered. So a wpuld be thief tries to flip the remote switch and it fails. Then he decides to seek the remote if he is smart enough to even anticipate it is being used as a lockout device, and that takes considerable time to hunt or trace starter wires. My starter remotes are behind locked doors, so first they have to break open the doors.

[TomTom]

Ok - please excuse the fact that it is a bit messy… but here is my initial wiring diagram.

I want:

1) one switch panel at the console to do VHF/ GPS/ cigarette lighter/ Usb and Nav lights (which will be mounted on T Top.) Anticipate 2 m run for everything except Nav lights which may be 4m total.

2) An independent bilge pump that is fused and wired direct from battery (under console) to bilge. For when boat on mooring. This will not be shut off my battery disconnect switch.

3) a second switch panel under rear gunwale that will operate wash down pump and tuna tube pumps. Before anyone asks why so many “bilge pumps” - I want to run each tube with its own pump from a live well (to avoid air bubbles).

I also want a spare bilge pump which can be switched on here at transom end. And maybe some underwater lights.

If I fuse this section with a 30 Amp fuse off the main cancelling (that in theory will also power the engine starter) will that be enough to protect the main cabling?


4) Is it sensible/ appropriate to send 2 big cables to the junction at the transom and pull the engine starter cables off here? Or should the engine start be an entirely different cable/ circuit direct from the battery?

This probably won’t be fused - though I have now entered a rabbit warren of opinions on both sides of this discussion. I see nothing is quite as straightforward as first appears! I can’t find the rating of a Yamaha 150F starter motor so am guessing this would need to be at least a 200 amp fuse?

Here is a diagram of what I am thinking…

[OrangeQuest]

The tuna tube pumps each need to be fused independently so if one shorts out it does not kill all of them.

Best for you to get a book that goes over wiring for a boat. Here is a source that I was able to pick up a dozen or so books on boat building and a few of them about the wiring of them. When they don't have a book you want, and they get it, they will send you an email.
https://www.thriftbooks.com/w/the-marin ... on=7678124