Canadian Yachting December 2017 - 36
MARINE ELECTRONICS
Peering Atop Islands
and Around Bends
The latest in AIS technology, regulations
and market offerings across North America
By David Schmidt
A thin breeze skittered across the Gulf of Maine, and a low cloud
ceiling stamped-out any moonlight, making for a dark night
aboard my dad's J/44, Southern Cross. My wife and I were standing watch with nothing to look at, save a few distant lights. While
my wife enjoys excellent vision, I suffer from severe red-green
color blindness that makes it hard to determine if I'm looking at
bow and stern lights, discreet vessels, or both. Given that in
August of 2006 Automatic Identification System (AIS) wasn't yet
widespread amongst recreational craft, we spent the next few
minutes trying to discern the nature of the scene before consulting the radar, getting on the VHF, and waking our captain.
We eventually determined that these lights belonged to two
moderate-sized commercial fishing vessels that were anchored
close together, somewhere off of Gloucester, Massachusetts,
and that passing well astern would be simple. While this situation illustrates how confusing nighttime navigation can be, AIS
technology has since removed the (ugly) word "assumption"
from most crossing situations, while also providing significantly
better situational awareness. This piece looks at AIS technology,
the latest CCG and USCG regulatory requirements, future AIS
applications, and the latest AIS offerings.
While AIS technology is capable of disseminating a wide range
of information, its most common use is to allow mariners to "see"
other nearby traffic to avoid vessel-to-vessel collisions. The basic
concept is fairly simple. An onboard AIS transponder broadcasts
a vessel's speed, course and location information from its GPS-
along with the vessel's unique, nine-digit Maritime Mobile
Service Identity (MMSI) number, which is assigned by Industry
Canada - part of Innovation, Science and Economic
Development Canada-over VHF channels, while also listening
for other vessels' incoming signals. Critically, properly programmed MMSI numbers allow a mariner to directly call another
vessel (think of a cell-phone number), rather than relying on easily
missed VHF broadcasts. Equipment depending, AIS information
can be overlaid onto an electronic nautical chart (or radar display),
giving navigators a tremendous level of big-picture awareness,
especially when paired with radar imagery.
There are two types of AIS available to mariners, namely Class
A and Class B devices. Class A AIS is typically used by commercial traffic (or for fast-moving recreational traffic) and features 212.5 Watts of transmitting power. Class A transponders have a
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Canadian Yachting
variable reporting rate that ranges from once every two to ten seconds, depending on the vessel's speed (this rate drops to once
every three minutes if the vessel is traveling at less than three
knots, and once every six minutes when the vessel is anchored).
Class A units are required to have a dedicated Multiple Keyboard
Display (MKD), and contemporary Class A units are designed to
display both Class A and Class B AIS target information.
Critically, Class A units broadcast their transmissions using the
Self-Organizing Time-Division Multiple Access (SOTDMA)
scheme, which is an automated method that allows different
users to efficiently share finite channel access.
Class B AIS is primarily aimed at the recreational marine
market (although it has some commercial applications) and will
eventually be available in two varieties, AIS Class B/SO, which
uses the same self-organizing SOTDMA scheme as Class A
units, and AIS Class B/CS, which uses a Carrier Sense Time
Division Multiple Access (CSTDMA) scheme to share channel
access. Unlike the SOTDMA scheme, which pre-announces
the time slots when it will be transmitting, AIS Class B/CS units
continually monitor the frequencies and select unused slots.
Moreover AIS Class B/SO units feature two to five Watts of
transmitting power and a reporting rate that ranges between
once every five to 30 seconds, depending on vessel speed. AIS
Class B/CS units feature two Watts of transmitting power and a
static reporting rate of once every 30 seconds. Both units reduce
their reporting rate to once every three minutes for vessels traveling at less than two knots, and once every six minutes for static
data. Given that most cruising yachts travel at speeds well-below
20 knots (the speed at which reporting rates become germane,
as fast boats can outpace their reporting rates when using AIS
Class B/CS), most cruisers can safely spec an AIS Class B/CS
transponder, provided that they do not require the extra range
afforded by a Class A or Class B/SO unit's additional power.
[N.B., while the United States Coast Guard (USCG) has
approved AIS Class B/SO units-as of this writing-they are
not yet commercially available.]
While Class B/SO units are required to have a dedicated
MKD, displays are optional for Class B/CS units. Because of
this, many AIS manufacturers build black-box Class B/CS units,
which are networked with the vessel's multi-function display
(MFD) in order to graphically present its target list atop cartography. Equipment depending, Class B units are compatible with
DECEMBER 2017
Table of Contents for the Digital Edition of Canadian Yachting December 2017
Vantage Point: Little Boat, Big Boat – Where Did You Start?
Club Profile: Gimli Yacht Club
Galley Guys: The Galley Guys Travel to Newfoundland
Travel Destinations: The Middens of Galiano Island
Profile of a Cruising Family: Redefining the Face of Yachting in Canada
Marine Electronics: Special Feature – A Guide to Maritime VHF Radio for Pleasure Craft
Marine Electronics: Special Feature – AIS - Peering Atop Islands and Around Bends
The Port Hole
Marine Electronics: Special Feature – WiFi Boosters
Sail Review: Dehler 38
Power Review: Cruisers Yachts Cantius 50
Power Review: Jeanneau NC 895
Summer Event Coverage: Poker Run 101
Crossing the Line: Flying Dutchman
Canadian Yachting December 2017 - Cover1
Canadian Yachting December 2017 - Cover2
Canadian Yachting December 2017 - 3
Canadian Yachting December 2017 - Vantage Point: Little Boat, Big Boat – Where Did You Start?
Canadian Yachting December 2017 - 5
Canadian Yachting December 2017 - Club Profile: Gimli Yacht Club
Canadian Yachting December 2017 - 7
Canadian Yachting December 2017 - 8
Canadian Yachting December 2017 - 9
Canadian Yachting December 2017 - 10
Canadian Yachting December 2017 - 11
Canadian Yachting December 2017 - Galley Guys: The Galley Guys Travel to Newfoundland
Canadian Yachting December 2017 - 13
Canadian Yachting December 2017 - 14
Canadian Yachting December 2017 - 15
Canadian Yachting December 2017 - Travel Destinations: The Middens of Galiano Island
Canadian Yachting December 2017 - 17
Canadian Yachting December 2017 - 18
Canadian Yachting December 2017 - 19
Canadian Yachting December 2017 - 20
Canadian Yachting December 2017 - 21
Canadian Yachting December 2017 - 22
Canadian Yachting December 2017 - 23
Canadian Yachting December 2017 - Profile of a Cruising Family: Redefining the Face of Yachting in Canada
Canadian Yachting December 2017 - 25
Canadian Yachting December 2017 - 26
Canadian Yachting December 2017 - 27
Canadian Yachting December 2017 - Marine Electronics: Special Feature – A Guide to Maritime VHF Radio for Pleasure Craft
Canadian Yachting December 2017 - 29
Canadian Yachting December 2017 - 30
Canadian Yachting December 2017 - 31
Canadian Yachting December 2017 - 32
Canadian Yachting December 2017 - 33
Canadian Yachting December 2017 - 34
Canadian Yachting December 2017 - 35
Canadian Yachting December 2017 - Marine Electronics: Special Feature – AIS - Peering Atop Islands and Around Bends
Canadian Yachting December 2017 - 37
Canadian Yachting December 2017 - 38
Canadian Yachting December 2017 - The Port Hole
Canadian Yachting December 2017 - 40
Canadian Yachting December 2017 - 41
Canadian Yachting December 2017 - 42
Canadian Yachting December 2017 - 43
Canadian Yachting December 2017 - 44
Canadian Yachting December 2017 - 45
Canadian Yachting December 2017 - 46
Canadian Yachting December 2017 - 47
Canadian Yachting December 2017 - 48
Canadian Yachting December 2017 - 49
Canadian Yachting December 2017 - 50
Canadian Yachting December 2017 - 51
Canadian Yachting December 2017 - Marine Electronics: Special Feature – WiFi Boosters
Canadian Yachting December 2017 - 53
Canadian Yachting December 2017 - 54
Canadian Yachting December 2017 - 55
Canadian Yachting December 2017 - Sail Review: Dehler 38
Canadian Yachting December 2017 - 57
Canadian Yachting December 2017 - 58
Canadian Yachting December 2017 - 59
Canadian Yachting December 2017 - Power Review: Cruisers Yachts Cantius 50
Canadian Yachting December 2017 - 61
Canadian Yachting December 2017 - 62
Canadian Yachting December 2017 - 63
Canadian Yachting December 2017 - 64
Canadian Yachting December 2017 - 65
Canadian Yachting December 2017 - Power Review: Jeanneau NC 895
Canadian Yachting December 2017 - 67
Canadian Yachting December 2017 - 68
Canadian Yachting December 2017 - 69
Canadian Yachting December 2017 - 70
Canadian Yachting December 2017 - 71
Canadian Yachting December 2017 - Summer Event Coverage: Poker Run 101
Canadian Yachting December 2017 - 73
Canadian Yachting December 2017 - 74
Canadian Yachting December 2017 - 75
Canadian Yachting December 2017 - 76
Canadian Yachting December 2017 - 77
Canadian Yachting December 2017 - 78
Canadian Yachting December 2017 - 79
Canadian Yachting December 2017 - 80
Canadian Yachting December 2017 - 81
Canadian Yachting December 2017 - 82
Canadian Yachting December 2017 - 83
Canadian Yachting December 2017 - 84
Canadian Yachting December 2017 - 85
Canadian Yachting December 2017 - Crossing the Line: Flying Dutchman
Canadian Yachting December 2017 - Cover3
Canadian Yachting December 2017 - Cover4
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