9.5.1. Electronic navigation system
Quite common today even on smaller yachts.
9.5.2. SSB
Very useful on ocean trips.
9.5.3. Radar
Increases safety when sailing at night or in bad weather.
9.5.4. Microwave oven
A microwave oven uses a great deal of energy (up to 1.5 kW) for a brief time. When the microwave is used for 12 minutes per day the consumption in Ah out of a 12 V battery is 1500 x 0.2 / 12 = 25 Ah.
9.5.5. Space heating
One should always opt for a diesel burner so that current consumption stays confined to diesel pump and fans. The current consumption is then kept down to approx. 5 A.
9.5.6. Air conditioning
Especially when operating on battery power, it is important to carefully look at the expected energy consumption.
9.5.7. Water maker
Some very efficient water makers are now available that work on 12 V DC. Current consumption is only 10 to 20 A for 30 to 60 litres of fresh water per hour. This has made a water maker (and thus also a freshwater deck shower!) a realistic extra for small boats used for blue water cruising.
The following table sums up the additional luxury that could be found on smaller boats. Power consumption has been based on a crew of 2 or 3.
Consumers
Consumption
Time / 24- hours
Consumption / 24- hour period
Watt
Amp
Hours
kWh Ah (12 V)
C Electronic navigation system
2
24
48
C SSB
12
0.1
7
L Radar
3
8
24
S Microwave oven
1500
0.2
0.3
25 15
L Heater
5
6 x 0.5 = 3
L Air-conditioning, cooling capacity 2 kW
700
6 x 0.5 = 3
1
(90)
L Water maker, 150 litres per day
10
5
50
Consumption per 24-hour period
2.0
169
Average consumption per 24-hour period
85
7
With all the additional equipment on board (except for the airco), the total energy need per day amounts to: - when sailing: 1.5 + 2.0 = 3.5 kWh, or 128 + 169 = 297 Ah - at anchor : 1.0 + 2.0 = 3.0 kWh, or 85 + 169 = 254 Ah Which translates to the following minimum battery capacity and average discharge current: - when sailing: 297 x 2 = approx. 600 Ah and 12.3 A discharge current - at anchor : 254 x 2 = approx. 500 Ah and 10.5 A discharge current
We are now going to see how to produce the required energy, for the “basic” yacht (1.0 to.1.5 kWh needed), and for the “full featured” yacht (3.0 to 3.5 kWh needed).
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