28 Marine Electronics Journal September/October 2018
tem. BoatUS reports that nearly half of fires
on boats are due to electrical system fail-
ures—corrosion in wiring splices and con-
nections, switches, fuse blocks, terminal
A basic wiring circuit for one bilge pump
contains several components: the battery, a
fuse block, terminal strip and the pump plus
connections, most of which are exposed to
the salt-laden environment. Every one is a
potential failure point. Multiply that by the
total number of onboard circuits—VHF,
brings the simplified sophistication of one-
touch control to vessels of all sizes.
Reducing failures at sea
Beyond all of those benefits, DSS offers
another huge advantage: fewer onboard fail-
ures of electrical components. The major
causes of boat breakdowns at sea are engine
failure and electrical system faults. Of those
breakdowns caused by engine problems, a
significant portion is due to the failure of elec-
trical components in the engine electrical sys-
fishfinder, AIS, and radar, to name a few—
and we’re talking about a lot of switches,
fuses, connection/splices and wire and deteri-
oration caused by corrosion in the marine
environment. DSS eliminates many of these
Big differences between systems
In contrast to traditional, or analog, electrical distribution systems, DSS systems do
not use electromechanical switches such as
those in toggles and circuit breakers. This
eliminates excess voltage drops, intermittent
connections and overheating due to corrosion, arcing, and loose and faulty connections, all the result of vibration, wear and tear
and salty air ingress. The principal differences
between the two systems are actually few, but
of considerable significance.
First, in the traditional system, the main
source of power is a short length of heavy
gauge copper bus bar, tapped and threaded
for contact screws, and located in the electrical distribution panel, centrally placed in the
boat. Power for each of the boat’s motors,
pumps, and electronics is run via heavy-gauge, high-conductance copper wire from
the panel to the individual devices. In a DSS,
the primary source of DC power is via a single
high-conductance bus, or “backbone,” such
as that used in a CAN or NMEA 2000 network, that runs the length of the boat. Connections to devices require only short cable
“drops.” Failure-prone components such as
electrical distribution panel, switches, and
fuses and/or electromechanical circuit breakers are eliminated.
Second, connection, protection and control of electrical and electronic equipment
are done by a circuit control module (CCM).
It is the interface device between the brains
of the system and the device being controlled. Different manufacturers refer to this
device by a variety of names—output interface (OI), power distribution unit (PDU) or
DC module (DCM)—but we’ll use the term
CCM to avoid confusion. The CCM is
located close to the device it’s controlling, in
Blink Marine’s Keybox circuit control module is a CAN bus relay module for electrical loads. Once
connected to various devices such as electric motors, bilge pumps and hydraulic actuator solenoids,
you can activate/deactivate them via a keypad.
*Jon Payne Ocean Aire Marine Electronics Santa Barbara, CA
How long have you worked with digital selective switching?
About a year, starting with a Moody 54 project. We dabbled with it servicing a few transient boats but the Moody was the first total project we did. We worked with Airmar
and Gemeco and got inside a CZone system—changed out some signal interfaces, repro-grammed modes and worked through firmware issues.
What did you like about DSS?
From the servicing and installation standpoints we see it as a real boon---it simplifies the
map. The distributed systems whereby we’re running trunk lines through the boat and
then the individual loads are distributed locally, as we start dealing with larger boats it
really cuts down on troubleshooting time. if you can follow the flow into that particular
zone and it’s there but not getting to the load, you don’t have to chase through the
More importantly, from the point of view of my customers when they come aboard,
all they do is choose the mode and everything in that mode is activated. it gives them
confidence and enjoyment because they can operate everything at a touch. it simplifies
running of the boat.
Not really. Rather it’s a great opportunity for the technically minded to step in and learn
how to modify these systems. All boat builders are going to get on board with this—it’s
coming. it saves them time and money. The programming is a little clunky. At the factory level people are a little gun shy to change modes. Boat builders don’t seem able to
augment the programming of CZone.
What’s the most complex DSS install you’ve done?
our experience is minimal at best—nothing complicated. And from the customer’s
perspective, it’s the simplicity of pushing one button and having everything they want
turn on, including a camera mounted 100 feet up the mast that has a view out to the