Modern Electrics

[laika]

On my 2012 task list is stripping out the nest of vipers which has distributed power round my (12m sailing) boat since I bought it. Rather than just replacing and better mapping what I've got, I'm interested in looking at what the current state of the art is in 12v power distribution.

The books I have and the ones I've seen most often recommended here tend to deal with stuff which hasn't changed much in the last 30 years.

Does anyone have any recommendations for literature which can give me pointers about what innovations in yacht power distribution there have been in the last few years that I might take a look at?

 

[Vara]

All to complicated for me, but this looks quite interesting;

http://www.yachtingmagazine.com/electronics/systems/distributed-power-systems

May set off a google trail.

 

[ghostlymoron]

There was a series on this in PBO last year or maybe 2010 by a Dutchman I believe. He seemed to have some good ideas and techniques. Modern practice is to use circuit breakers rather than glass fuses maybe include some battery monitoring display and allow a few isolators for future expansion. Wiring is recommended to be tinned marine grade but most of us use automobile cable internally and marine for external. Put a mouse in any conduit/cable routes so you can pull in extra cables in future if you need them.

 

[lustyd]

I can't imagine a huge amount has changed in power distribution. The basics have never changed for this because you need certain size wires and something to protect the circuit and that will always be the case.
The area that has changed is data networking so you may be better off looking at that. I suspect there is some benefit to having power one side and data the other too but that is a guess

 

[halcyon]

All to complicated for me, but this looks quite interesting;

http://www.yachtingmagazine.com/electronics/systems/distributed-power-systems

Things have not changed in the last 30 years, back in 1983 we were fitting circuit breakers, battery monitoring, and load shedding to extend battery life. Most circuit breakers on the market to-day were available in the mid 1980's. The article mentions MOSFET control / circuit protection via data bus, that goes back to the mid/early 90's.

So to answer the OP's question, no there is nothing new with modern switch gear, just the marketing spin.

To rewire a 12M yacht,
1 ) It depends on boat layout - number of cabins,
2 ) Distribution of electric equipment - what is the power / number of electrical items in each cabin,
3 ) How much you want to spend.

It may be cheaper to fit central distribution supplying all circuits, or run a power bus and control circuits from a panel in each cabin.

Brian

 

[laika]

Thanks for the replies. I'm pretty much good with the pure data side of things. However I knew nothing about can bus electrical switching control and the article vara pointed me at has been an excellent jumping off point for further research.

 

[Bobobolinsky]

Can bus switching is a great step forward from even 10 years ago, with a single power cable distributing power, with local nodes supplying individual items. I said to a guy who had just rewired his boat, what about the cost. To which he pointed to a rats nest of copper and told me that the system had saved 90Kg of deadweight copper.

 

[William_H]

Power distribution systems

As said I really don't think in practice things have changed much. The distributed power systems might have value if only to show it is up to date but I think good old copper wire and switches will serve you best.
You can imagine in a Boeing 747 or A380 with perhaps 400 passengers each with a reading light (and sound system) they want to control that huge savings in copper wire weight can be had with digital signaling to a box at the required light which is connected to a common rail.
However in your boat you have different current requirements and different locations. Cabin lights will in many cases be switched at the light fitting. I just can't see the value of digital signal type control from a common rail. good luck olewill

 

[Stu Jackson]

The biggest change has been to remove the alternator output from the 1-2-B switch and run it to the battery bank directly, and add a voltage sensitive relay to charge the other bank. This makes the switch a USE only switch, and it no longer determines which bank gets charged. This avoids the dreaded "brother-n-law turned the switch when the engine was running and fried my alternator" syndrome. We in the US send out AO to the house bank, you in the UK prefer to send the current to the starter (reserve) bank. It's much safer, easier to understand, and avoids costly damage.

Here are some switching options: http://c34.org/bbs/index.php/topic,6604.0.html

 

[ianabc]

Port and stbd wiring

It has been sugested on the origami metal boats forum in Yahoo, that wiring each side of the boat with heavy duty tinned wire then tapping in for each fixture is the way to go.

Saves on wire which is getting expensive now with rising copper prices.

Each side probably fused and then each circuit protected with a standard 12 volt magnetic circuit breaker of the world type.

Used 64 used military surplus breakers in mine and built the panel but if I were starting again I would consider this idea.

 

[halcyon]

It has been sugested on the origami metal boats forum in Yahoo, that wiring each side of the boat with heavy duty tinned wire then tapping in for each fixture is the way to go.

Saves on wire which is getting expensive now with rising copper prices.

Each side probably fused and then each circuit protected with a standard 12 volt magnetic circuit breaker of the world type.

Next stage on is to fit the circuit breakers in the light switches, these connect to a pos and neg power bus. So one small panel can distribute 4 circuits in the cabin, with minimum cable. Why switch nav lights at the chart table, fit switch panel under mast, and pick up power from power bus. Also save all the cost and problems running micro's or computor.

Brian

 

[AngusMcDoon]

Can bus switching is a great step forward from even 10 years ago, with a single power cable distributing power, with local nodes supplying individual items. I said to a guy who had just rewired his boat, what about the cost. To which he pointed to a rats nest of copper and told me that the system had saved 90Kg of deadweight copper.

I was thinking of making something like that myself. The cheapest processors start at about 50p at retail small order-count price. That doesn't buy much cable. I'm not sure how to do signalling over power lines so I was thinking about a 3 line system - power, ground and data. Rather like Seatalk in fact.

 

[Boo2]

Each side probably fused and then each circuit protected with a standard 12 volt magnetic circuit breaker of the world type

Is it really worthwhile to use fuses and breakers ?

Boo2

 

[prv]

The biggest change has been to remove the alternator output from the 1-2-B switch and run it to the battery bank directly, and add a voltage sensitive relay to charge the other bank. This makes the switch a USE only switch, and it no longer determines which bank gets charged. This avoids the dreaded "brother-n-law turned the switch when the engine was running and fried my alternator" syndrome. We in the US send out AO to the house bank, you in the UK prefer to send the current to the starter (reserve) bank. It's much safer, easier to understand, and avoids costly damage.

Agree - although I use the "American" option of connecting the house bank directly to the alternator - the only device in line with that connection is a fuse. This ensures the bank that really needs it gets the best-quality charge (the Smartgauge web site has an example of how multiple connections in the charge cable affects the charge voltage).

Given that charging happens automatically, and under normal circumstances there's no reason to connect the house bank to the starter motor, I have dispensed with the 1-2-both switch entirely. The house battery feeds the distribution panel, the engine battery feeds the starter motor and the engine panel. For emergency parallelling the battery monitor has a "link" button that closes the charging relay for 30 seconds. I know some people just carry a jump-lead for this relatively uncommon scenario instead.

The smart power distribution systems mentioned do seem like they might have potential on a big yacht, although personally I think I'd just go for multiple traditional panels spread around the boat near their respective loads. The only load that's really distributed is lighting, and LEDs mean that the cables for that don't need to be as chunky as they used to be.

Pete

 

[prv]

Is it really worthwhile to use fuses and breakers ?

If you have no fuse on the distribution cable, a short there will burn your boat down (cos they're big cables).

If there's a fault on one of the spur cables, the big fuse on the distribution cable won't blow, because it's designed to pass the maximum current drawn by the whole boat at once. So your little spur cable will melt, perhaps not burning the boat down, but definitely causing damage.

So yes, you do need appropriate protection for both cables.

Pete