Our goal is to keep the boat as simple as we can while nevertheless wanting full liveaboard comfort and autonomy! So that still creates a fairly long list of systems, but we do want to eliminate the need for:
- Air con – through great ventilation, light hull and deck colours and heat reflecting film on windows
- Diesel generator – through plenty of solar, a hydrogenator and large lithium battery bank
- Propane/butane gas – through all-electric cooking
Our key system choices:
Operational:
- Nav electronics: B&G plotter- speed – depth – wind – AIS – Radar
- Pilot: B&G software / Raymarine electric linear drive
- Comms: VHF – Satellite – Cell phone
- Electric winches x 2
- Windlass
- Nav lights
Domestic:
- Induction hob
- Combi microwave / convection oven
- Fridge 1 – Drawer fridge – easy access to frequently used stuff – Isotherm INOX 130
- Fridge/Freezer 2 – Top entry – most efficient for cold air retention – National Luna 110 Legacy Double
- Hot & cold pressurised fresh water – 40lt calorifier
- Electric toilets x 2
- Watermaker – DC / energy recovery system – can be efficiency run direct from the batteries – Schenker Zen 50lt/hr
- Heating – Webasto diesel / electric
- Washing machine – bulkhead mounted – weighs only 18kg – DaeWoo Mini
- LED lighting
- 12v charging points & 240v sockets
- Portable waterproof speakers – JBL – driven by iPhone / iPad – eliminates need for built in sound system
12v DC + 240v AC supply
Most of the CM’s electrical system will be by Victron, to ensure compatibility and facilitate back-up service/info as required.
The CM is well designed with all major electrical equipment fitted close to the middle of the boat near the domestic battery bank, avoiding long cable runs. This makes a single 12v DC system practical. 12v is generally required for nav systems etc but many boats need to add a second, 24v, system as well due to long cable runs to high load equipment.
12v Service Batteries: 4 x Lithium 200Ah LiFePO4
12v Engine Start Batteries: 2 x 85Ah AGM
Inverter/charger: 3000w to supply the AC equipment: Hob and combi microwave – a few smaller galley appliances – AC sockets for misc equipment
We’ll have to balance use of appliances at any one time but the next inverter size up (5000w) would be significantly larger and heavier, so we think a bit of active management will be a worthwhile trade-off… and discipline us to be careful with consumption! Overcook it and the inverter will say No.
Charging
Rush will have four battery charging systems, making good use of renewable options, maximising autonomy and providing a level of redundancy:
Solar – 2000w of panels on the bimini/cabin top – see later Solar System post.
Hydrogenator – The Watt&Sea was one of our favourite bits of kit on the Pogo, ideally suited to fast cruising boats such as the Pogo and the CM because output increases rapidly as speed climbs over 7 knots (20amps@7knots – 44amps@10 knots). Admittedly the Pogo had lower consumption (small fridge etc) but it felt great to leave an anchorage, set the sails, engage the pilot, lower the Watt & Sea and, a short while later, have full batteries and more power than we knew what to do with while the boat sailed itself!
The Watt&Sea will slot into a bracket on one of the transoms and be removable for security in port, washing and servicing. The prop is nylon so it’ll be worth carrying a spare or two in case it gets damaged by impact with flotsam although, touch wood (pun intended…sorry…) that’s yet to happen to us.
Alternators – Both engines will have 140amp alternators for charging when motoring. We expect the solar and hydro systems to cover our electrical power requirements most of the time but it will be possible to run one engine to recharge if (OK, when) the infamous Wadhams weather strikes and it rains for days while at anchor. It’s not perfect to run an engine purely for generation but, at 30hp, they’re pretty small so fuel consumption will only be around 1lt / hr and there are many advantages to not buying / carrying / servicing another stand-alone diesel engine (generator).
Shore power – the inverter/charger unit enables plugging in to charge the batteries and heat the water when in a marina.
