ELECTRICAL AND NAVIGATION SYSTEMS

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NAVIGATION SYSTEMS

Navigation systems are designed to provide easy to use equipment in the wheelhouse in a sound ergonomic layout - which includes a small chart table for charts, sailing directions, parallel ruler and other navigation paraphenalia as well as flat surfaces for the inevitable coffee mug and sarnie plate.

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  The result is the wheelhouse layout as above.

Navman radios were chosen for their dual DSC/ATIS capability.  UK is not currently a signatory to the Basel Agreement which mandates the use of ATIS radios but CEVNI requires ATIS radios to be carried on continental waterways.  To achieve an element of future proofing, I decided to get DSC/ATIS radios.  On purchasing the first 7100 in UK, I discovered that on UK supplied radios the ATIS functionality is disabled.  Navman UK swapped my radio for a Dutch spec radio and I purchased a second Dutch radio in the Netherlands.

I decided to forgo a chart/radar plotter and stick with paper charts and a laptop PC with charting software.  In place of a chart plotter, I bought a small Furuno radar.  Possibly the way ahead is to use a Yeoman Chart Plotter, which combines the redundancy afforded by having a paper chart, with the accuracy provided by GPS.

I have recently revised the radar mast and added mounts for a Navtex aerial,  2 x GPS and 2 more VHF aerials.  The GPS and VHF aerials are mounted so that when the mast is lowered, the aerials can by moved back to a vertical position.

L3 Communications Protec W Inland AIS installed with data feed to a Windows PC providing geo and AIS data.  PC runs NavMon PC - a free AIS plotting software that also has a variety of functions including CPA with alarm which is useful for those sneaking up from behind and an anchor watch alarm which alarms if vessels drags anchor.

Of course all this electronics requires linking together.

Other communications equipment includes a full code flag set as well as ensigns, pilot jacks, house flags and dress ship lines.  Flags were initially supplied by www.mrflag.com and I then discovered that MrFlag is supplied by Magellan Flags and that flags from Magellan are considerably cheaper.

ELECTRIC INSTALLATION BASICS

The electric system was designed at the outset to ensure AC and DC separation.  AC circuits are routed along the port side and DC circuits along the starboard side.  The main exceptions are in the engine room where AC cables cross over the the DC side to supply the inverters and charger etc and where DC control circuits are required to activate AC devices.  Cables are fed through 3 inch diameter pipes under the side decks.  Outside the cable pipes, they are sleeved where required.

 DC SYSTEM

The DC system has both 24v and 12v elements.  The domestic battery is 24v 920Ah C10 and consists of 12 large 2v cells.  These cells are heavy and when I weighed them I discovered that they are 48kg each when empty - and I put 12 in the back of my Golf hatchback!! They were originally designed for use in de-gaussing barges and the flash deperming of warships.  They are capable of repeatedly discharging at 5000A, and should have a long life as a domestic battery - at least 15 years.  A drawback of the battery is that the cells are flooded lead acid and at high charging voltages will give off hydrogen and oxygen.  The battery is in a large sealed box under the galley floor in the bilges, which is a much cooler location than the engine room where it was originally to be located.  A DC brushless fan controlled by one of the Victron inverters is started to remove the gases and vent them out of the battery box whenever the voltage approaches the gassing voltage during charging.  The provision of an auto watering system and battery cell caps that reduce water loss was investigated, but not used due to cost.  And it is better to have a monthly check of battery anyway and top up when necessary - and I use a garden 9l pressure sprayer.  The engine starter battery is also 24v, whilst the generator battery is 12v.  The main battery charger and inverter are 2 24/3000/70A Victron Multiplus units which provides reasonable 140A domestic battery charging and also allows some redundancy and a Heart Interface Combi remains as a back up unit, albeit with modified sine wave output.

Filling the dry charged cells was not as difficult as had anticipated.  I bought 150 litres of SG 1.280 acid from CPC Batteries in Twickenham, rubber gloves, syphon tube and small plastic tap and used DPM membrane as protective sheeting.  After all the cells had been connected together I commenced the filling, starting the syphon using postive air pressure into the top of the 25 ltr container rather than sucking on the tube - not recommended!!  The filling was very simple and any drips were mopped up with a caustic soda solution.  After filling the cells, the voltage and temp started to rise from their dry charging and they were then charged at 50A with the bulk charge lasting for 4 days.  The Victrons seem to be excellent and being configurable via software give great control.  I was welding one afternoon using a small inverter welder and the boatyard shore power dropped off.  The Victron immediately changed over and supplied the welder.  I did not notice the change.

Two 24v Leece Neville alternators are fitted to the engine - a 110A and a 95A.  Both have been fitted with smaller than normal pulleys so that high charge currents are available at low engine rpm.  At engine idle, 700 rpm, 130 amps are produced, rising to 180A at canal/river cruising rpm, 1200rpm.

All wiring is generously sized to minimize voltage drop and I have aimed at 3% drop maximum throughout.  Whilst I was researching voltage drop, I found that much advice only considered the voltage drop from the switch to the load, and did not include the drop from the battery posts - it can and does make quite a difference.  I used a spreadsheet to assist me calculate the culmulative voltage drop and the cable lengths required.  It also provided me with a cable numbering system.  As a result some cable are really quite large - for example the main feeds to lighting junction boxes are 6mm2 and even the cables to lighting units are 4mm2.  Feeds to heavy DC equipment - an electric toilet drawing 20A - are 35mm2 - I specified 25mm2 but the supplier did not have it and substituted 35mm2.

I also discovered a complete lack of suitable distribution boards/panels to provide large current supplies.  These include up to 150A to supply the inverter and 50A to the Xact, and also accept large current input from the battery charger.  Plus I needed the facilites for an "always on" section - for bilge pumps and alarms and a lighting section powered by the XAct.  I therefore made up my own panel.  The copper bus bars are 150mm2, and will carry currents of up to 400A - which is more than I intend using.  25mm x 6mm x 1000mm copper bars were supplied by Tranect.  There is a short busbar to feed midi and mega fuses and then other bus bars for fuses below 30A and to provide negative return paths.  The main battery feed is a parallel pair of 70mm2 cables to a 275A domestic battery switch and it is fused next to the battery to meet the ISO/ABYC rules.  There is also an emergency parallel switch to supply the engine battery.  Another length of bus bar provides the common ground for both the DC and AC systems next to the engine battery box.  The same copper bus bar is used to make the links for the battery cells - Chloride Industrial Battery Ltd having advised that the cell to cell links should be at least 100mm2.

After much research I decided to use a "Smartbank" to solve the dilemma of how to charge 2 batteries.  Using this device, the engine alternators are connected directly to the DC panel positive busbar using 35mm2 cable, I may increase it to 70mm2.  The domestic battery is also connected to this busbar.  The engine battery is connected to the domestic battery using a Smartbank and relay.  The Smartbank monitors the voltage of both batteries and operates a heavy duty relay when the engine battery needs charging or is experiencing a load.  In many ways it is similar to a battery to battery charger but with one very important advantage - it allows the full alternator output to charge the engine battery if needed, rather than 4 or 10 Amps as with battery to battery chargers.  I also learned much about battery charging voltages - above 28.6 volts the amount of additional charge going in with higher voltages tails off dramatically, so whilst an alternator controller will attempt to charge at 29 or more volts, it does not translate into quicker charging.  It is also a very cost effective solution - Smartbank and relay is around 100.

The engine battery has a separate master switch and the cable is also fused to meet ISO/ABYC.  I decided to mirror auto practice and all systems that are used when the engine is running are fed from the engine battery.  These are switched from the wheelhouse panel.  Again, I was not particularly enamoured with the commercial offerings of panels and made up my own panel which also matches the shape of the engine panel.

The battery charger and inverter are 2 24/3000/70A Victron Multiplus units which provides reasonable 140A domestic battery charging and also allows some redundancy.  The house and engine batteries are monitored by a Xantrex Link 20.

 Lighting is a mix of 12v and 24v DC Halogen and 240v CFL.  Downlighters from Eurobatteries are liberally sprinkled across the deckheads and fitted with either 12v lamps paired in series where possible or 24v 20w and 10w lamps.  These have been wired up in groups.  These circuits are fed by an XAct Minor.  This device auto switches between the 240v AC supply and the domestic battery supply - which ever is available - and supplies exactly 24v for halogen lighting.  Max supply is 50A or 1200W - more than enough for all the lights switched on at the same time.  It can also be used as a 24v DC power supply.  This was another Ebay bargain at well less than 10% of the retail price.

The latest purchase has been a few solar panels.  After much thought I eventually decided on 6 of Unisolar's PVL-68 stick on panels.  These are designed for mounting directly onto "roof pans" - as they call them in USA.  They have an integral adhesive and sealant , are only 4mm thick and can be walked on.  The panels themselves are thin film amorphous silicone and although not as efficient as cystalline varieties, which means a bigger area is required, they are better under cloud, when shaded, when not facing the optimum orientation and when in N European latitudes.  Over a year their total power output should exceed at least a 80w crystalline panel.  The panels will be stuck down on the wheelhouse roof.  Yet again UK prices seem a little OTT and I've imported them direct from USA from www.readymaderesources.com, who have been really helpful and seem to make several despatches to Europe.  The panels are controlled by a Morningstar Prostar 15 amp controller which has a full 4 stage charging system and takes both temp and voltage sensor inputs to really maximise the charging.  I am hoping that these will make me independent of shorepower throughout the year when KEI is left, running at least the fridge and central heating during the winter and the deep freeze as well during the summer.  [Oct 08]

AC SYSTEM

Again the main AC distribution boards are a custom designed and built units.  KEI has 4 AC sources - Shore, 3.5kW engine AC Alternator, Generator and Inverter.  The engine alternator immediately brings its own problems along to the party - it requires a 12v feed, it is Quasi Sine Wave and is centre tapped 120-0-120, but it was a bit of a bargain so I wanted to use it - if the engine is turning I might as well have some 240v AC. To switch all these sources in a logical sequence, I designed a system using industrial contactor pairs with mechanical interlocks and timers. This system is simple enough to ensure automatic changeover between power supplies with complete electrical and mechanical safety features so that supplies cannot get mixed.   There are also 2 small QSW inverters to run the fridge, if 240 volt, and CH system when the barge is left unoccupied and everything is left on 24v DC - and possibly relying on solar panels to maintain the battery state.  Diagram of AC supplies and switching is here.

Another advantage of having an isolation transformer was  illustrated well during the initial AC circuits installation.  Using a DVM, I discovered that the boat yard negative line was 12v positive with respect to earth at the shore supply breaker onboard.  On the boat side of the IT, quite correctly, the negative was at zero volts with respect to the hull earth.  If I had only fitted a galvanic isolator, the negative, and consequently the entire hull,  would have remained at 12v positive with respect to earth.  In the water, this potential is probably enough to drive a current that could kill a person - 80 milliamps is sufficient.

Electrical load is always a concern and whilst provision is made for air conditioning to be fitted, it does consume an enourmous amount of power.  Low profile traditional ceiling fans in the saloon and fwd master cabin are installed - having lived in HK ceiling fans have proved to be entirely adequate in providing a cooling breeze.  Reverse rotation fans will also assist efficient heating in the winter.

Oct 08.  After a few weeks of living onboard it is clear that controlling use of battery capacity is most important.  With careful control, we can run off the battery in excess of 3 days.  Our battery/inverter combo are quite capable of powering all electric kit including the 3kw immersion heater and 3kw domestic oven.  Running the immersion heater is not a good idea, but we do warm things up, for say 20 mins, in the oven from the inverter.  I have now decided to improve control of the inverters and will be fitting an adapted mains digital timer to control the Victron Multiplus remote panel.  This Tesco TE7 timer is adapted to run off 24v DC and consumes only milliamps.  It will enable the inverter, when KEI is left,  to be switched on a couple of times a day so that the central heating can run for a couple of hours, and then switch off the inverter.  Or when onboard it will switch off the inverter in the silent hours when it is not needed, switching on again in the morning for the central heating.  I am convinced that having DC equipment for essentials such as water pumps, fridge/freezer, head pump and lighting is the way to go - especially if using solar panels.  There is little energy efficiency in taking 24v solar power and inverting it to power 240v devices.

The Fischer Panda 12 generator seems to be a good size as well.  With the 30Amp transfer switch in the inverters, it means that with one inverter switched on both the oven and fwd immersion heater can be run, totalling approx 28A through the transfer switch.  With another 10A being taken by the inverter to charge the battery, this totals 38A, out of the 48A max from the FP12, which is a good loading.


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