photo contest - Yacht Essentials

PHOTO BY GLENN HAYES
How to supply the electrical power required
by yachts traveling to foreign ports can be a
challenging problem. There are many issues
to contend with, and a practical solution for
ample and reliable electricity is more important than
ever these days when one considers the array of new
megayacht marinas opening the world over.
Before plugging into shore power at a foreign port, there
are several factors to consider. First are the voltage of the
shore power and the line frequency. In the US, voltage
is usually 120/240V AC with higher voltage available in
some marinas for larger yachts. Voltage in other parts of
the world may fall between 115V DC and 415V DC. The
line frequency is the number of times the voltage alternates
in a second and is measured in Hertz (Hz). In the
US, this is 60Hz (or 60 cycles per second). In Europe and
many other places overseas, it is 50Hz.
Apart from the differences in voltage and line frequency,
there’s also the issue of voltage fluctuations caused by
the utility provider, by wiring and grounding issues, or by
heavy load from other users along the dock. The other
problem is how to connect to the shore power and what
adapters are needed. There are many different connec-
72 YACHT ESSENTIALS
A PRACTICAL
POWER SOLUTION
Engineer’s Corner
BY GLENN HAYES
tors, and the well-prepared vessel will have a supply of
various adapters on hand.
One method to tame shore power issues is using onboard
generators to supply voltage, and while this does solve the
shore power issue, it has its drawbacks. There’s the cost of
fuel and maintenance of running the generators. Wear and
tear of the generator should be considered and is amplified
if the generator is run at low output levels over extended
periods. Generator noise is another issue at marinas and
will not make your visit to the dock a popular one with vessels
nearby. Many ports worldwide are in the process of requiring
vessels to plug into shore power at berth to reduce
emissions and comply with new, “greener” mandates, effectively
banning generator use in port.
Running on inverters with battery chargers re-supplying
the energy is another option. This works fine if the energy
draw isn’t too large and the chargers have enough
capacity to recharge the batteries in off hours, but this is
not always possible. If you use this option, it must also
be understood that at 12 volts you will need between
12 and 15 more amps for each amp of 120V AC used. If
you have a 24V DC system, the amps required from an
inverter would be about half of the 12V system. Larger