Simple wiring diagram for small craft

[CDK]

Regularly I've seen questions on this forum about electrical wiring because that is still a mystery for many boat owners.
Here is a simple wiring diagram for motor- and sailing boats with one engine and just the basic equipment. There are only 7 wires shown that connect the engine bay; I omitted temp. gauges, rev counters etc. which all have their own wires or cables. The ignition wire is not used for diesels, but there it can be used for the fuel valve.

A friendly reader in the US is invited to translate my wire sizes from mm2 to AWG numbers. Parts like the diode bridge and 4-way battery switch are available from Vetus in Europe, I did not look for US suppliers.

Drawings are shown as .JPG, but also available as .CDR (Corel draw).
Boat owners who have no idea what this all means should of course hire a qualified technician!

COMPACT
DUTCH
KNOWLEDGE

as usual......................

[Knut Sand]

Pretty.

I once, somewhere suggested automatic 12 vdc diode light in the engine compartment, biwired together with the bilge pump. Also on the same biwire an alarm/ buzzer located at the steering position (with on/ off switch, normally set at "on") telling the driver that something is going on down under..... In case, it can cive you a few extra minutes.... For a low cost....

[BillyDoc]

Nice, Knut, very useful!

BillyDoc

[Delane]

Re-wired my J-24. Basically pulled everything and started over. The goal was simplicity in design and to not use one of those typical switch panels. I used a 100 volt A/C switches. Have any questions, please ask.

[BeauVrolyk]

Originally Posted by Delane

Re-wired my J-24. Basically pulled everything and started over. The goal was simplicity in design and to not use one of those typical switch panels. I used a 100 volt A/C switches. Have any questions, please ask.

I am looking at a rewire on my boat as well, similar size and complexity. I was wondering why you didn't use one of the plastic boxes with the clear lid to contain all the junctions? I get a fair amount of water aboard, probably a lot like a J24 when races, and the last junction strip just turned into a ball of salty corrosion.

Beau

[Delane]

My wiring is inside of a closed compartment and the boat is very dry. Tabernacle mast set up and everything has been re-beaded. Bone dry and I have a solar vent to circulate air.

[BeauVrolyk]

Originally Posted by Delane

My wiring is inside of a closed compartment and the boat is very dry. Tabernacle mast set up and everything has been re-beaded. Bone dry and I have a solar vent to circulate air.

You're lucky. The water in my boat doesn't leak in, it's carried in by the soaking wet spinnaker and headsails during sail changes in heavy seas. That and the sopping foul weather gear etc... We typically sail in 20 to 30 knots of breeze and big waves - it's wet. It must be nice to have a dry boat, none of the J24s around here are dry if they're raced.

B

[BeauVrolyk]

Originally Posted by CDK

Regularly I've seen questions on this forum about electrical wiring because that is still a mystery for many boat owners.
Here is a simple wiring diagram for motor- and sailing boats with one engine and just the basic equipment. There are only 7 wires shown that connect the engine bay; I omitted temp. gauges, rev counters etc. which all have their own wires or cables. The ignition wire is not used for diesels, but there it can be used for the fuel valve.

A friendly reader in the US is invited to translate my wire sizes from mm2 to AWG numbers. Parts like the diode bridge and 4-way battery switch are available from Vetus in Europe, I did not look for US suppliers.

Drawings are shown as .JPG, but also available as .CDR (Corel draw).
Boat owners who have no idea what this all means should of course hire a qualified technician!

I am curious why you've used both circuit breakers and fuses. Is there a specific reason? I have had great luck with waterproof circuit breakers and pretty bad luck with the contacts on fuses.

Beau

[Delane]

The switches are not the breaker type. That little fuse box was the most expensive part of the whole panel at $40 by the time it arrived.

[CDK]

Originally Posted by BeauVrolyk

I am curious why you've used both circuit breakers and fuses. Is there a specific reason? I have had great luck with waterproof circuit breakers and pretty bad luck with the contacts on fuses.

Beau

No, I used switches and fuses, but of course you could also take automatic circuit breakers if you don't mind the extra cost.
Because this post was only meant to help people getting started, I did not supply detailed info. Perhaps I should have.

Fuses are absolutely necessary to protect your safety, but with proper, careful wiring they should never do what they are designed for: blow. So the should cost as little as possible. The automotive type with knife contacts costs only a few cents and makes reliable contact with a socket or crimp terminal. Glass fuses in a fuse holder are very unreliable in a marine environment but you already found that out. Some grease or Vaseline prevents corrosion of fuse contacts but is seldom used.

[zamgod]

CDK, can I ask what the box at the bottom left of your drawing is?
The one where most of the wires feed into.
Thanks.

[CDK]

That box is the engine compartment.
There are only 7 wires connecting it to the rest of electrical parts that is located elsewhere on board, i.e. under the steering console or in the cabin.

[TollyWally]

Very nice basic set up to get people started.

I've wondered about taking common cheap ac switches like Delane used and attaching pigtails potting them with epoxy.

[gonzo]

If you have fuel onboard, those switches are not spark protected. That means the possibility of fire or explosion.