View past issues of
the Reference Point
• online at
15
T
he idea for converting to electric
propulsion started when we
read an article by Nigel Calder.
Friends thought it was crazy to convert
a bluewater cruising sailboat to electric
propulsion. Others, like us, were
intrigued and urged us to proceed. The
following, taken from a longer article
about the entire conversion and 2,500
miles of sailing, is a section detailing the
configuration of the electric propulsion
system in our Hylas 44, “Marama.”
THE THREE MAJOR COMPONENTS TO
AN ELECTRIC PROPULSION SYSTEM ARE:
1. MOTOR, CONTROLLER, THROTTLE
& BATTERY MONITOR
2. BATTERIES
3. CHARGING SOURCES
After researching for several years, we
chose the Clean eMarine (formerly
ASMO Marine), Thoosa 12000 system.
The Thoosa 12000 is a 12kW, 72volt
DC system rated for boats 33-45 feet in
length. We wanted a reliable motor with
a proven quality history and a complete
system that we could install ourselves.
From our research, we knew to expect a
shorter duration at the top-end speeds
than we got from our diesel. The style
of sailing we try to do - day sails or
long range cruising (but with no time
constraints) - works with the trade-off
for continuous top end boat speeds. We
chose to implement a “hybrid-electric”
approach, using our existing 5.5 kW
NextGen Generator.
Before converting, our boat had a single
30amp shore power inlet and the genset
was wired for 120v AC output. During
the conversion, we added a second
30amp shore power inlet and rewired
the genset to 240v AC output. This
shore power configuration allows us to
use one shore power line to supply our
house bank charger, water heater, and
AC outlets. The second shore power line
supplies our Sterling 24v30 charger and
other AC loads. The 240v AC genset
configuration allows us to utilize the
two-line configuration we use when
on shore power, but more importantly,
the configuration supplies 240v AC
to the Zivan charger, which sends 72v
DC through the batteries to the electric
motor. The Zivan charger never runs off
shore power to avoid the potential for
By Bill McManus, Customer of ABYC Member Annapolis Hybrid Marine
THE BATTERY BANK IS
CONFIGURED INTO THREE 24V DC
BANKS THAT ARE COMBINED TO
MAKE A SINGLE 72V DC BATTERY
BANK USING CONTACTORS. IN
ADDITION TO STAYING WITHIN
ABYC STANDARDS, THIS
CONFIGURATION ALLOWS US
TO CHARGE THE BATTERIES IN
SMALLER BANKS.
PROPULSION SYSTEM
IN A
HYLAS 44
CONFIGURING
AN
ELECTRIC
