3 wire boat wiring

[Pennywise]

Hi there

Sorry if this has been done to death already, I've been asked by a client if I would be interested in rewiring his boat, I'm an electrician by trade so pretty competent in the theory and installation . My problem is terminology, in that I don't know what the system the client has asked me to install is called lots of googling hasn't thrown up a company or forum hit, so I must be calling it the wrong thing. He's described it as a common 2 wire ring with an additional data cable run along side it, so you can give each load a specific ID and so limit the current drawn at that outlet or light etc, he's said it quite a new method and quite expensive as with all things boat related I suppose and it saves cable. Anyway any help would be most appreciated even if it's just a link to a company or the name of the system.

David

 

[DaveS]

This might not be much help, but since no-one else has replied...

Don't have a name for it, but there was an article on this in one of the yachty comics a year or so ago. I would guess it's a variation of CanBus or similar as is starting to be used in vehicles, and there may be more than one system out there. It might be worth asking these people if they stock it or know who does:

Merlin Equipment Ltd
Unit 4, Cabot Business Village
Holyrood Close
Cabot Lane, Poole
Dorset, BH17 7BA
England
Phone +44 (0) 1202 697979
Fax +44 (0) 1202 691919
sales@merlinequipment.com

 

[mitiempo]

Here is a link that may explain what the owner is referring to - distributed power.
http://www.cruisersforum.com/forums/f14/capi2-distributed-power-system-36975.html

 

[halcyon]

He's described it as a common 2 wire ring with an additional data cable run along side it, so you can give each load a specific ID and so limit the current drawn at that outlet or light etc, he's said it quite a new method and quite expensive as with all things boat related Id

Fly-by-wire, you have pos and neg bus, with tappings feeding distribution units, these are controlled a micro processor or PC via data cable, try Victron, Vetus.

It's not new, I was designing a system back in 1995, never moved it on as it was more complex and costly than a normal system.

You need to make sure back-ups are in place, heard of one boat that had the processor shut down mid channel. Lost engines and all power, including VHF, so be carefull.


Brian

 

[rhumlady]

I was just thinking along the same lines as Brian. I prefer the KISS method, keep it simple stupid, then when it breaks it is easily sorted.

 

[elton]

Sounds like CAN bus. Now common in motor vehicles, and increasingly built into new boats.

 

[Phoenix of Hamble]

Im rewiring at the moment and looked at this. Way too risky was my conclusion... Stuffed from one end to the other with single points of failure.

 

[William_H]

Distributed power

I think the OP needs to ask the client what he wants by way of equipment and supplier. The equipment should come with instructions.
Meanwhile it sounds like the client just wants the latest and greatest.
This style of power supply is very successful in aircraft where you have 400 seats with 400 reading lights cabin call and sound system and a need to add and remove seats.

It could really only be practical on lighting and low power devices on a boat.
Anything requiring real power will need to have its own hard wiring to allow for heavy wire and appropriate fusing.
Even then it must be simpler and more convenient to have a cabin light switch at the light rather than a central control point.
So the point is I think unless it is a really complex boat as said he would be better off with ordinary wiring.
good luck olewill

 

[oldsaltoz]

I rewired a 60 foot trawler some years ago, the skipper wanted to control the switching on and off everything from the bridge, including things like the lights in the crews quarters, deck lights and power points throughout the vessel.

Also 4 Video cameras, 2 generators, freezer monitoring, hydraulics monitoring and bilge pumps to name a few.

I shudder to think how it would have come together with a fly-by-wire set up back then, it was no simple task.

I used the simplest logic I could come with based on a ring mains and loops and more cable makers than I have used in 20 years.

After completion it took me 4 long days just to draw up the schematics and then have then sealed in clear plastic, 2 sets. and put together in book form.

The end product was that almost nothing would work or start unless the skipper threw one or more of the many switches on the bridge.

If I was ever silly enough to this again I would be looking into the fly-by-wire systems available today and hope my price was too high to get the job.

Good luck and fair winds to all.

 

[Cookee]

An NMEA 2000 system would do this but it would require everything to run off this system, there is the technology to do it - Try These people

 

[BAtoo]

You need to make sure back-ups are in place, heard of one boat that had the processor shut down mid channel. Lost engines and all power, including VHF, so be carefull.
Brian

Quite agree about backups, & the KISS principle. Delivered a yacht for a friend that he had specified with a computer controlling everything! So when we couldn't get the computer to boot we couldn't even turn on a light let alone any nav gear etc.....

 

[elton]

An NMEA 2000 system would do this but it would require everything to run off this system, there is the technology to do it - Try These people

As I just learned from this interesting article, NMEA 2000 is based on CAN Bus.

 

[BAtoo]

Im rewiring at the moment and looked at this. Way too risky was my conclusion... Stuffed from one end to the other with single points of failure.

Just looked at Elton's link to CAN Bus in Wikipaedia - quite agree with you far too complex as I couldn't get my head around it

BATTERY - wire - FUSE -wire - SWITCH - wire - INSTRUMENT

 

[halcyon]

I rewired a 60 foot trawler some years ago, the skipper wanted to control the switching on and off everything from the bridge, including things like the lights in the crews quarters, deck lights and power points throughout the vessel.If I was ever silly enough to this again I would be looking into the fly-by-wire systems available today and hope my price was too high to get the job.

Funny thing is that we deveopled the system in 1995 for that situation, a Sealine that never was, a trawler type motor yacht.

But we were looking at distribution nodes that were groups of solid state circuit breakers, to feed light switches, equipment, etc. These were switched from the main panel in the wheel house to isolate a circuit, or each breaker had manual control on the breaker. The one feature we had then, which I've not seen yet, is that if you had a cable fault, bad joint, the switch board would tell were the fault was loacted on the boat.

Brian

 

[prv]

BATTERY - wire - FUSE -wire - SWITCH - wire - INSTRUMENT

Take something like a big fancy mobo, though, with underwater lights, illuminated makeup mirrors, electric tin-openers, infrared shower taps, motorised hatch covers, and a self-tanning booth for the bimbos on the bow. With your scheme you'd need to ship so much wire that the damn thing would never get on the plane.

That's the kind of boat this stuff makes sense on.

Pete

 

[halcyon]

Take something like a big fancy mobo, though, with underwater lights, illuminated makeup mirrors, electric tin-openers, infrared shower taps, motorised hatch covers, and a self-tanning booth for the bimbos on the bow. With your scheme you'd need to ship so much wire that the damn thing would never get on the plane.

That's the kind of boat this stuff makes sense on.

Pete

But what are you gaining by having it micro controlled, bar having having a central switch panel.

At the moment I can do around 95% of it without the need for a micro, but the same layout, just interested for ref. Been down the micro route, now trying to do it without the micro.

Brian


Brian

 

[BERT T]

WIRING.

I've done my share of boat wiring in my time even on boats with a walk in engine room. My advice would be to forget it, unless he plans to carry a full time "SPARKY" as part of his crew.

 

[Cookee]

As I just learned from this interesting article, NMEA 2000 is based on CAN Bus.

I think it's more than that - NMEA 2000 IS a CAN bus system. It's what is in every modern car now and as PRV says it would save a lot of cable but it needs to be reliable.

 

[Rivers & creeks]

I've often wondered by boats over about 30 feet aren't wired with a sort of 12v ring main, you'd have a thick juicy cable running round the boat and just take a small spur off it for the individual item. The voltage loss would be minimal and instead of huge runs of cable going back and forth for every single item you'd have just one very thick red and black cable going from the battery. It's not true distributed power but it gives a lot of the wiring benefits.

 

[prv]

I've often wondered by boats over about 30 feet aren't wired with a sort of 12v ring main, you'd have a thick juicy cable running round the boat and just take a small spur off it for the individual item.

You would of course need a fuse where each of these small spurs joins the main cable, to protect the spur (that's precisely the role that the fuse in your mains plugs at home play). Presumably the inconvenience of having fuses sprinkled all over the boat instead of collected together in one place is the reason this isn't done. Although bigger boats do sometimes adopt a halfway house of having sub-distribution boards to hold all the fuses for an area of the boat.

Pete