Electricity in a cruise: Basics

When we decided to take a trip of several days by boat, one of the most important points is the energy on board. Without electronic navigation instruments, or night navigation lights or any electrical appliances that make life easier for us on the cruise not work.

 In the event of total failure, it is clear that the ship afloat and continue browsing. But it is very risky to travel at night without lights, or not being able to take advantage of the latest electronic navigation instruments. Without electricity, anchor windlass does not move, and can be very hard to raise it by hand. If we take a leak bilge pump could not work forcing us to use the cubes. Without electricity the boat engine can not be started, making it very risky entry into port using candles. All the problems that can cause an electrical failure on board can become very serious issues in case of bad weather and strong winds.

Even without electrical breakdown must have very clear what our consumption and generation capacity on board. The electrical system must be able to produce electricity by any means available, store and distribute it to different devices boat.

We must be aware of the installation of our ship and learn some basic notions of electricity and have some tools and instruments with which to work on board.

It's not about giving a course in electricity. Knowing Ohm'slaw and some of its variants can assess daily consumption on our boat, and therefore calculate a suitable battery capacity and design the delivery system and restoring more suitable electrical power. The more consumption on board, the faster the batteries discharge.

Normally we talk about power in watts (eg navigation lights may consume a total of 50 watts) and volt (normally batteries boats are usually 12 volts) and is also spoken of current (or intensity current) is measured in Amperes (eg can see that an electrical apparatus on board says consume 15 Amp).

It is very important to know that the product of the volts by the current, indicates the power in watts. For example, if our electric anchor windlass says consume 70 amps and must operate at 12 volts, then the power consumed is 70x12 = 840 watts; Power = voltage x current. In the same formula, we can obtain the current = power / voltage.

The best way to get the total consumption of a ship is to calculate the current of each of the devices, to multiply by the hours that we will use. For example: A light bulb has a power of 24 watts consumes a current of 2 amps (24watios / 12 volts = 2Amperios) Your current consumption is 2 amps and whether we will leave on for 15 hours, then we will have consumed battery 2 x15 amp hours = 30 amperes (really should say ampere-hour is an amount of energy consumed)

Imagine the other hand, the GPS consumes 3 amps and leave it on all day. Then consumption has become of 3x24 = 72 Ampere-hour. In this example, the total consumption of the ship during this day would have been 30 + 72 = 102 Ampere-hour.

We will add consumption on board for total daily consumption. Some devices have marked their consumption somewhere that is difficult to access when it is already installed. In other cases, a badly made installation can alter consumption marked factory. For these reasons, making it more comfortable is to use an ammeter tells us. If the switch panel of the boat has installed an ammeter, simply connect one after the other equipment on board and we will be pointing their consumption, then multiply by the time of intended use.

But very few boats are installed ammeter or are unreliable, so we must use one of ours. There are very affordable digital devices as allow us to know the voltage, resistance, and current.

With these multimeters, we can know the current battery voltage. For it will scale in Volts and 20 Volts calibration, which is the nearest 12-volt voltage to be measured. To make contact with the red and black wires on the battery, we will read the voltage value. The red wire on the positive and the black in the negative. If we put the cables in reverse the measured voltage will come with a minus sign. In this way, we can find the positive because if you leave a minus sign on the screen, where we will be in the black cable and if the reading is positive value is where we have the red wire.

To measure current must put the scale in amperes and put the circuit in series with the meter, ie as if the water meter of irrigation pipeline. We can remove the positive terminal of the battery and connect the ammeter to the battery and the terminal that have withdrawn from this.

Most DMMs are capable of measuring currents up only 10 amps, ie 120 watts (10Amp x 12 Volts), which does not allow measuring high currents, electric windlass, or starter motor ships. To measure this consumption we can use another instrument called a clamp meter. The clip will simply embracing the cable through the circulating current to be measured. No need to disconnect or connect anything, as this works by induction.

The meter scale measuring resistance measurement allows us to track a cable is not cut or short. For example, will scale in 20 KOhms, and we find that if the measurement cables are separated far indicates '1' meaning that indeed this value is infinite, ie the circuit is interrupted or open. Conversely, if the measurement leads together we will see on the screen goes to zero, indicating no resistance between them and therefore the measured value is zero Ohms. If a fuse is either the measured value is 0 Ohms. If you are reading cast will be infinite. A broken wire between the two extremes we want behave measure for measurement purposes as the fuse. If it is cut measure will infinite. If properly give zero or close to zero if the cable is long.

As an example discussed below actual consumption of various appliances on a sailing boat about 12 meters, which together reach about 200 ampere-hours each day. Therefore batteries must have the ability to store this energy and somehow we must be capable of recharging in an approximate value to this figure. In the example given, we found that about half of consumption is produced by the electric refrigerator which comes to consume 4 to 6 amps and usually works 70% of the time and the autopilot that having to make small corrections on helm also consumes about 5 amps.

For the time values ​​in the consumption table, we have assumed a voyage of about 11 hours per day, of which 4 hours night sailing, after which anchored leaving on the Anchor Alarm offered by GPS, and anchor light. We can see how the use of the VHF radio is very small, although much increase their consumption while we issued, and that other devices due to the short time of use barely contribute to the total sum, despite its high potency in functioning. For example, the water pressurization pump only works for short periods to recharge circuit pressure when necessary. Powerful engines as a bow thruster or anchor windlass will not count any value in the table as well as work for very short periods of time when they do the boat engine must be running, not consuming energy battery.

 More details learn you can visit this site.