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a small electric thruster, which the team
had to remove to comply with the R2AK’s
rules, but which will be aboard any ASVs
deployed for scientifi c research.
Power is a precious commodity on any
boat, and Nav2 runs on two lithium iron
phosphate batteries that provide 40 amp-
hours, as well as on four deck-mounted
solar panels (rated to 35 watts in full sun)
that trickle-charge the house batteries.
Arutunian says Nav2 uses just half an
amp-hour per hour to operate under nor-
mal conditions, giving it an 80-hour range
without any topping of ; this range can
be increased by decreasing sample and
reporting rates.
Nav2 is governed by a series of algo-
rithms that allow the boat to navigate.
It’s important to remember that just
like an autopilot, Nav2 can’t anticipate
oncoming puf s or wave sets, but instead
reacts to changes in conditions. The algo-
rithms rely on a series of performance
notches that trigger the vessel to adjust
trim. For example, if the apparent-wind
angle is 120 degrees, Nav2’s program tells
it to pay out a set amount of sheet; if the
angle decreases to 90 degrees, Arutunian’s
code automatically instructs the winch to
pull in the sails by a designated amount.
“It will trim to every sail angle,” says
Arutunian, “and it has the smarts to know
when to tack upwind.”
Nav2 is also capable of navigating shal-
low waters — a challenge for the larger,
more complex ASVs and underwater
drones currently used to gather data. To
meet the team’s scientifi c goals, Nav2 is
designed to carry 25 pounds of scientifi c
instruments, with bursts of up to 50 watts
of onboard power available. Nav2 fea-
tures transducer housings for an acoustic
Doppler current profi ler, which allows sci-
entists to quantify how quickly water is
moving across a given water column; a con-
ductivity and temperature sensor, which is
used to study physical properties of ocean
water, including water salinity and heat;
and a fl uorometer, which is used to mea-
sure the intensity of fl uorescence (i.e., the
emission of light from algae or other ocean
fl ora). Additionally, Nav2 can deploy towed
sensors, and it can be fi tted with bespoke
instrumentation and sensors.
Not surprisingly, Nav2 carries a sophis-
ticated communications system, which
it uses to upload data, receive navigation
instructions (such as new waypoints or
data-sampling patterns), and report on
any AIS crossing situations. Arutunian
points to this communication system —
which consists of Wi-Fi, a cellular modem
and an Iridium modem — as the project’s
most time-consuming work. Because
Nav2 will upload data via an expensive
Iridium connection when it’s of shore,part of Arutunian’s challenge was to min-
imize the volume of data that needs to
be transmitted. He achieved this by add-
ing data compression to the system. As a
result, each of Nav2’s reports contains a
mere 150 bytes of burst data.
Shoreside, Nav2 is controlled by
Arutunian’s custom app, which allows
users to set new waypoints, manually
trim the sails, and monitor Nav2’s vari-
ous navigation and scientifi c instruments.
While almost all of the vessel’s operations
are autonomous, the ASV is designed to
alert the Navocean team of any threaten-
ing AIS crossing situations via email and
SMS text message; these are manuallynegotiated — via the app — to ensure that
humans are highly involved with Nav2’s
collision-avoidance scheme.
Unfortunately, despite plenty of
eyes being fi xated on Nav2 during her
R2AK attempt, the strong southerly
breeze died before the ASV reached the
Strait of Juan de Fuca. When a power-
ful 10-hour fl ood tide began pressing
her back toward Port Townsend, the
Navocean team made the call to aban-
don racing, as mathematically there was
no way that Nav2 could reach Victoria
within the mandated 36 -hour window.
While the Navocean team wasn’t
thrilled with this tidal setback, the success
of an identical ASV, currently searching
for harmful algae blooms of the Florida
coast, more than satisfi ed their proof-of-
concept testing. The team plans to market
their autonomous vehicles to universities,
scientists and research groups at a price
point between $70,000 and $100,000
(depending on instrumentation). Here
the Navocean team believes they have
another advantage, as many other ASVs
on the market can cost north of $250,000.
To further lower the barrier to entry, they
are also considering rental schemes to
make the technology available to students
and researchers who have more modest
funding. “These things have the potential
to change the whole research-gathering
world,” says Arutunian.
Additionally, the Navocean team fore-
sees possible government and military
interest in tiny, near-silent ASVs that can
patrol otherwise desolate waters for up to
six months at a time without maintenance.
“One of the potential uses of these drones
is that we can gather AIS data from places
that no one is getting it right now,” says
Stuart Lochner, who joined the Navocean
team in 2015 to help with sales and mis-
sion support. “All that data is being sent to
us; we could then provide it to servers like
MarineTrai c. So this is potentially a data
portal, or a water-based repeater, for places
where they don’t get AIS trai c right now.
The military and U.S. Coast Guard are the
kind of people who like to know what kind
of trai c is out there.”
So while Nav2 may never win an of -
shore sailboat race, there’s little question
that this multipurpose ASV represents a
huge advancement. With Nav2’s ability to
autonomously sail from one area of study
to the next, negotiate shallow depths, and
transmit highly compressed data with its
(relatively) moderate price tag, odds are
good that a project that began with a bot-
tle of wine, a simple model sailboat, and a
dream could have far-reaching impacts on
the scientifi c community.David Schmidt is CW’s electronics editor.DESIGN
CONSIDERATIONS
Scott Duncan says the team’s
fi rst-generation MiniNav fea-
tured a double-ended canoe
design. Nav2 maintains this
shape in her bow sections,
which Duncan says o ers a
good balance between reserve
buoyancy and the ability to
negotiate seas, but the team’s
most recent ASV features a tra-
ditional transom and sheer line,
with a length of 6.5 feet and a
narrow-beam hull (20 inches
at the widest point). A deep-
draft keel (2.5 feet) provides
stability and righting moment,
while a relatively short rudder
(roughly 8 inches deep) pro-
vides steerage.
Duncan constructed the
hull’s topsides and under-
carriage using S-fi berglass and
epoxy, which he hand-laid over
impact-absorbing foam, leav-
ing epoxy-coated foam for her
watertight interior. The deck
is also built using a foam core
sandwiched between layers of
S-glass, and carbon-fi ber rein-
forcements are used throughout
the vessel. All up, including its
navigational electronics and
instrumentation, Nav2 weighs
just 85 pounds and can carry an
additional 25 pounds.
“She is a displacement-hull
vessel, designed to perform
well at low speed,” says Duncan,
who explains that faster speeds
introduce unwanted “noise” to
the vessel’s scientifi c instrumen-
tation. While some noise can be
fi ltered out (such as the sound
of the rudder’s actuator), sim-
ply operating at slower speeds
makes the platform more viable
for scientifi c research. But to be
successful in its research goals,
the vessel has to be seaworthy.
“The vehicle must be able to
navigate a broad range of con-
ditions,” says Duncan. “If we’re
not collecting data, we’re not
doing much.”