Upgrade Your Boat - Part 6 - Electrical
By Simon Boyde
Loads of progress on the boat now. Deck off, steering system replaced, new binnacle, new rudder, new deck cleats. Partial rebuild of the interior is underway, and just about complete in the forward cabin and head. Which is where it will stop for a few months because of preparations for the China Sea Race - we are missing our offshore fix!
But it is very dark up forward, because there are no lights yet.
Two issues: the old light fittings have definitely reached retirement age and the wiring connecting the lights to the batteries has one foot in the grave.
Replacing lights gives us the opportunity to upgrade how we do the lighting, and how the light distribution works. On a modern boat you will see extensive use of downlights (small spotlights) which rather than being placed simply in the middle of the boat, are placed down the sides of the ceiling which distributes the light to the sides of the boat as well as creating more light, reducing the claustrophobic feeling inside the boat at night. Cave Canem, a Beneteau First 42, when new, had 12 lights in the cabin. By the time we have finished it will have around 40!
Which lights? LED of course!
We have gone with LED lights from Roca (www.rocamarine.com). Very nice-looking single power LED and triple power LED lights. We always thought that these power LED lights emitted less light than a conventional G4 Halogen spotlight. Wrong. A friend who, for some reason, has a digital light meter, discovered they put out around 20% more per LED than a conventional 10W Halogen bulb, when measured in lumens. And for a power consumption of around 10% of the halogen bulb! And they stay cool.
The cool bit is very important for LED lights. The LED emitter is a semi conductor, just like the processor on your PC, and just like that processor it needs to be kept cool. The money in an LED light is in the heat sink - the lump of metal which transports heat away from the LED bulb itself and dissipates it through air. Household LED lights are built on the assumption that there will be a lot of air space. Properly marinised LED lights are not just of a more robust construction, they also have larger heat sinks to deal with the reduced air space above them. This makes them more expensive, but cheap ones will fail quite quickly, and LED bulbs in conventional light housings will fail very fast indeed (no heat sink see).
The old wiring system at the front of the boat supported three lights (head, forecabin and reading light). We are replacing this with 8 lights - head, two reading lights, main forecabin light, forward forecabin light, and four small spots. And of course, new wiring is required!
Ripping out the interior meant that we pulled the old electrical system out of the forecabin, and we will later replace the rest as well. This needs to be done. The wiring is 25 years old, and though it has lasted well, it is definitely at that time when replacement is due.
As this is a phased update on the boat, in that we intend to use the boat in between fits of construction, we had to consider quite carefully how to rewire in bits. Also the costs and time scale of a rewiring job. Most boat owners believe that electrical wiring is a black art so they get someone else to do it, and then when the bill arrives they go ballistic over the time charges. Wiring takes a very long time. Our estimate, if we were to get the boat professionally rewired in Hong Kong, for a full job, is approximately HKD250,000! A lot of money. A 42 foot sailing boat has many kilometres of wire in it, probably more than the average house.
Why is this? Well, we have independent power. We make our own from wind, solar, gensets or engine alternators. We don't just have lights, airconditioners and cookers, we also have a mass of other cabling for safety, instrumentation and navigation purposes. And to top it off, we can't use a ring main like in a house, all the wires run back to a central wiring centre - the main switch panel.
Here is an example of a conventionally wired boat (a pretty standard motor yacht):
Many years ago, in the bus and truck world, zone wiring systems began to come into use, and are now universal. The boat world has followed. With these, rather than having one central breaker panel, there are multiple clusters of breakers round the boat. This is impossible to manage unless you have a way of remote switching them, which luckily someone has done for us, in a tough and protected marinised format.. We looked at the options, umm-d and ah-d over which one we should go for, and selected the BEP CZone system.
With this, your switch in the wall is remote: it uses lightweight signal wire to signal to a special interface nearer to the thing that needs to be turned on or off, that it should switch the power on the relevant circuit. These remote switches are programmable - you can have multiple switches switching on one device, or one switch used to control several devices. For example, freshwater pumps on boats that heel will run continuously once the tanks get a bit low - because of a lack of water on the supply side. One good way of getting round this is to have a timer switch on the freshwater pump - switch it on and it automatically switches off after 15 minutes. Obviously if you are in the middle of a shower this would be a pain if the switch was on the main panel, so the best way to do this is to have a pushbutton ON switch at each water consumer - galley, heads, showers so if it turns off, one push and it is on again. Easy to do this with CZone.
You can set up modes on the display panel. For example night time sailing could be one mode, which disables all interior lights unless they are red.
And most of all, you massively reduce the amount of cabling you need, and you can wire it up in stages. Before, if you had six different powered items in a cabin, you ran six pairs of cables, via the controlling switch, all the way back to the breaker panel. Now, you run one pair of power cables to the output box which is located in the same area as the items you need to power, and simply run cables from your powered devices to the outlet box which is remotely switched. It may sound complex, but with straight forward planning it is easy to achieve. Take a look at the following illustration and compare it to the previous one.
Much, much simpler. We estimate that a full re-wire job using this system will cost only HKD150,000.
To prepare for this we moved the service batteries from where they were sitting underneath the chart table, to underneath the floorboards at the bottom of the companionway. There are 700Ah of batteries on board - which is a lot in a 42 ft sailing boat. This is so we can, for one night a week, run the airconditioner we are putting in the forward cabin from the inverter. All we need to do after that is replenish the batteries.
This airconditioning trick is not possible with everyone's products. We are using a 5000btu unit from Webasto. These draw around 30% less power for the same cooling effect than their competitors, and have much lower startup current requirements. We estimate that with the compressor running for 30% of the time that over ten hours the unit will pull 200Ah overnight. An additional 150A Balmar alternator from Victron has been installed on the engine so the batteries can be quickly recharged Later willcome the solar panels so that they can do the re-charge job during the week.
To power the airconditioner we are running the Victron EasyPlus inverter charger. This comes pre-wired with cables to the batteries included, as well as built-in RCDs to protect against possible electrical shocks downstream of it. It is effectively a CE rated AC system in a box.
The next article discusses the communications and GMDSS equipment going on board.
Simon Boyde is a Director of Storm Force Marine and regularly races Cave Canem