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NAVIGATOR OPERATING MANUAL
NW Explorations
It is with this concern that we can cite a reality: If we need more electricity than the batteries alone must
provide, and if the propulsion engine isn’t running, we will need to get our electrical power from an alternative
source! That’s the most important reason why we plug the boat in to shore power or use the generator: To
keep from running down the batteries. For by using battery chargers getting their power from shore power or the
generator, we can keep the batteries charged, or, at least, from getting too low.
In modern, luxury cruising boats, however, there is another important factor: Some of the “goodies” we like to
have on board such as hair dryers and microwave ovens require ordinary household electricity. This is 120
volts AC. It is different from DC. So if we want to use these things when we’re not at a dock, we must have
another way to get 110 volts AC, and for this we use the generator or an inverter, an amazing high tech gadget
that takes 12 volts DC from the ship’s batteries and makes it into 110 volts AC!
So here’s what we’ve got:
•
A lot of stuff running on 12 volts DC with that electricity from the batteries;
•
To keep the batteries from running down, we have alternators run by the engine, and battery chargers
that get their power from shore power or the generator;
•
For the stuff that runs on 120 volts AC, we have shore power, the generator, or, for making AC out of the
batteries’ DC, the inverter.
4G2: DC Batteries
The batteries on this boat are not just one, big all-purpose
battery. To have redundancy, there are actually several
“banks” of batteries assigned different tasks.
A “starting bank” of one battery (located under the forward
engine room teak bilge flooring) is used for starting the
engines only. That way, we won’t run it down playing the
stereo, for instance, and then be unable to start an engine.
This battery is charged by the engines when either is
running, or can be charged by the battery charger if it is on
when there is shore power or the generator is running.
A second bank of batteries is called “the house battery”.
This bank is made up of the other batteries forward and
outside of the starboard engine in the engine room.
Connected to this are all the pumps, interior and exterior lights, horns, navigation and radio gear, etc. This bank
runs the boat’s “house”. It is charged by the alternators on the engines and, when there is shore power or the
generator is running, by the battery charger and/or by the inverter if they are on.
When the starting button is pressed on either of the engines, a special high-capacity switch (called a “solenoid”)
closes and connects the starting and house batteries together! This way, we can be virtually positive that our
engines will start.
And a third battery (smaller, under the generator) is used exclusively for starting the generator. What
redundancy!
Since a battery works by making electricity through a chemical reaction, one component of which is water, we
need to be sure the batteries have water in them; this battery servicing is normally done routinely every few
weeks by the boat’s owner or charter company.
Most the house batteries are in the engine room,
starboard forward.
