I.
Index
II.
Project
Overview
III.
Objectives
IV.
The
Process
A.
Organization
of the Test
B.
A
typical AIS Event
V. Lessons
Learned
A.
Transponder
Inter-Operability.
B.
Sensor
Input to Transponders.
C.
Integration
of AIS into Bridge Systems.
D.
Broadcast
of Environmental Conditions.
E.
Summary
of Lessons Learned by Bridge Teams.
VI.
Summary
VII.
Recommendations
A.
Non-SOLAS
Ship Carriage of AIS
B.
Re-broadcast
ARPA Targets.
C.
Make
AIS part of the Integrated Bridge System.
D.
AIS
effect on VHF Communications.
E.
Transit
Schedule.
F.
AIS
and Navigation Aids.
G.
Environmental
Conditions.
H.
Messaging.
I.
Verification
of own ship transmissions.
J.
Display
Preference Profiles.
K.
Target
Display.
L.
Target
Table.
M.
Target
Information Display.
N.
Target’s
ROT display.
O.
Entering
Static & Voyage Information.
VIII.
Acknowledgements
Appendix A..
In this project the Bridge Teams of 3 modern cruise ships
evaluated the current implementation of AIS during the summer of 2002 while
cruising British Columbian and S. E. Alaskan waters. Their evaluation resulted
in findings and recommendations aimed at improving its value as a navigation
aid.
Bridge Teams formulated their recommendations so
specifically that, in the process, they defined the meaning of ‘AIS-Aided
Navigation’. They developed detailed specifications of how AIS should aide
navigation and what changes should be made both to the system and its
environment to attain true ‘AIS-aided navigation’ as a state of the art in
all of its aspects and dimensions.
AIS was found to be a potentially very powerful tool
that, if implemented correctly, will reduce the number of near-misses and
collisions because it will significantly improve the OOW’s ability to
anticipate and avoid potential collisions. Anticipation will be
improved primarily by AIS’ extended range, its capability to see around a
point and by improving target’s path predictions. Avoidance will be improved
by clearly identifying targets for hailing purposes via VHF.
The
original main objective of the test was to verify that AIS allows a ship's
Bridge Team to become aware of nearby vessel traffic that cannot either be
seen visually, or acquired by ARPA due to topographical features, even if
other ships carry transponders from other vendors.
The
second objective was to determine to best way to integrate AIS into the
electronic chart or radar display. This objective was broadened during the
test to include development of specific recommendations to improve the value
of AIS as an aid to navigation.
Due
to various technical difficulties three other objectives could not be attained
during the test:
·
Test
Inter-operability between AIS and Non-AIS transponders through a gateway on
Bowen Island
·
Assess the
effect of AIS on VTS communications
·
Assess the
value of broadcasting real-time environmental conditions via AIS
To
ensure that Bridge Teams’ recommendations lead to actual AIS improvements,
this report will be distributed to all who are in a position to act on them.
This includes:
·
All relevant
committees and work groups of IMO, IALA, IEC, ITU
·
Coastal
Authorities and VTS Operators
·
AIS
Information Display Vendors
·
SOLAS Ship
Operators
The
recommendations, along with this report, will be published on www.bcmarine.org/wmc,
were briefly discussed at an AIS Seminar in Vancouver on September 30th,
2002 and will be discussed at an AIS Conference to be held in Seattle on
November 19th, 2002.
Readers are encouraged to comment on the recommendations
by responding to:
Rick
Bryant
Secretary
Western Marine Community Coalition
100 - 1111 West Hastings Street
Vancouver, British Columbia
V6E 2J3 Canada
bryant@bcmarine.org
www.bcmarine.org/wmc
This project was an initiative of the Western Marine
Community (WMC), an association of shipping interests based in Vancouver, BC.
WMC received funding from the Canadian Coast Guard, Transport Canada and the
North West Cruise-ship Association. Holland America Line-Westours, Inc, Royal
Caribbean Cruises, Tideland Signal Corporation, Transas Marine and Radio
Holland (Canada) provided in-kind funding for the project. WMC awarded the
contract to manage the project to Marine Management Consulting.
Invitations to participate in the test were extended to
cruise lines in January 2002. Celebrity Cruises, Holland America Line-Westours,
Inc. and Royal Caribbean Cruise
Lines accepted the invitations but, eventually, Celebrity Cruises had to
withdraw from participating in the test due to technical reasons.
The Bridge Teams of 3 cruise ships conducted the test of
AIS in British Columbia and S. E. Alaska.
The
ships involved in the test were
- VOLENDAM
- ZAANDAM
- VISION
OF THE SEAS.
Holland America Line-Westours, Inc.’s VOLENDAM and
ZAANDAM are sisterships:
Length
238 m
Beam
32 m
GRT
63,000
Speed
23 Knots
Passenger
Capacity 1440
VOLENDAM
entered service in 1999 and ZAANDAM in 2000.
VOLENDAM
They are equipped with SAAB TransponderTech transponders
that are connected to a Leica Display. They are also connected to a NaviSailor
3000 ECDIS Version 2 and to sensors for Heading and ROT. The ECDIS receives
ARPA target information from the NACOS Integrated Bridge System (IBS), which
is manufactured by STN Atlas Marine Electronics, GmbH.
VISION OF THE SEAS
Length
279 m
Beam
32 m
GRT
78,491
Speed 22 Knots
Passenger
Capacity 2,200
VISION OF THE SEAS entered operation in 1998. For
purposes of the test she was equipped with a Tideland Signal/MDS transponder
that was connected to a NaviSailor 3000 ECDIS Version 2. The ECDIS was
installed on a laptop computer that was acquired for purposes of the test of
AIS. The transponder was not connected to either the heading or the ROT sensor
and the ECDIS did not receive ARPA targets, COG or SOG from the IBS (‘Voyage
Management System‘). Sperry Marine manufactures this system.
Once the transponders were installed each Bridge Team
received a pre-test briefing during which they were asked to evaluate AIS and
to present their findings and recommendations during a debriefing session at
the end of the test, two month later. The Bridge Teams were provided with a
set of criteria to use for the evaluation in a letter (See Appendix A).
The Pre-test Bridge Team Briefings were conducted July
13, 14 and 15. The debriefings were conducted September 9, 15 and 28. This
gave the Bridge Teams about two months to evaluate AIS.
During this period all three ships mostly made weekly
roundtrip cruises through S. E. Alaska from Vancouver, BC.
Also participating were 3 ferries from the British
Columbia Ferry System:
- SPIRIT
OF VANCOUVER ISLAND
- SPIRIT
OF BRITISH COLUMBIA
- QUEEN
OF NANAIMO
They were equipped with a Tideland Signal/MDS
transponders that was connected to a NaviSailor 2500 ECS.
These ferries operate between Tsawassan and Vancouver
Island/Gulf Islands or well South of the routes of the cruise ships.
All participating ships and ferries operated their
transponders on AIS1 (VHF Channel 87B) and AIS2 (VHF Channel 88B).
AIS Base stations on Bowen Island and at Delta Port
operated on AIS2 and on VHF Channel 88A. For this reason communication between
the base stations and participating ships was intermittent.
The Delta Port Base Station was set up to transmit
real-time observations of winds, currents and tides.
Other ships that were acquired on AIS in the course of
the test were a SeaSpan tug, DAWN PRINCESS, AMSTERDAM and RADIANCE OF THE
SEAS.
During the test there were about 40 ‘AIS Events’
where participating ships passed. Following is a description of a typical
event.
Here you can see the track of VOLENDAM from Juneau to
Skagway. The arrows show VOLENDAM’s Heading and COG. The AIS target for
VISION OF THE SEAS has just been acquired. It is labeled with VISION’s MMSI
Number (636010801) because static and voyage data have yet to be received that
would allow translation of the MMSI number into the ship’s name. VISION’s
AIS target was acquired at a range of 30 NM, which is typical. TCPA is 62
minutes.
It takes 27 minutes before the MMSI number is translated
into the ship’s name. The range is now 17 NM and the TCPA 35 minutes.
VISION’s ARPA target is acquired at a range of 9.5 NM
and a TCPA of 19 minutes.
Zooming in on the VISION shows minor differences between
its ARPA target (A6) properties and its AIS target (636010801) properties. The
differences are small enough for these targets to qualify for consolidation
into a single one.
Note that the VISION icon has been replaced by an outline
of the ship that is aligned with the COG and shows the position of the
transponder’s GPS antenna.
VISION is making a course change. Both its ARPA and its
AIS target leave a ‘breadcrumb’ trail (green dots). The COG of the AIS
target has changed well before the COG of the ARPA target, indicating that the
COG value that is received from VISION’s GPS is more up to date than
ARPA’s derivation of COG from consecutive radar sweeps.
VISION is now directly behind VOLENDAM and in its Radar
Blind Sector. VISION’s ARPA target (A6) is wandering over Lincoln Island
while the AIS target inspires confidence.
Transponders from different vendors were found to
inter-operate. Specifically the TransponderTech and MDS transponders did
exchange AIS information and there was some evidence toward the end of the
test that both types of transponders also received AIS information from the
Seatex transponder on RADIANCE OF THE SEAS.
The only caveat was that messages that originated from
the Leica Display were received only on the Leica display of the receiving
ship. Similarly messages that originated on the NaviSailor were received only
on the NaviSailor of the receiving ship. The root of this problem may be that
the Leica and NaviSailor use different message types.
VOLENDAM
Bridge Team
Several
times during the test ZAANDAM and VOLENDAM exchanged messages via AIS. ZAANDAM
and VOLENDAM, unlike VISION OF THE SEAS, share the same AIS set-up. Messages
originating from the messaging feature of a ship's NaviSailor were received
only on the NaviSailor of the receiving ship. Similarly, messages originating
from the messaging feature of a ship's Leica were received only on the Leica
display of the receiving ship.
IMO regulations state that own ship Heading and ROT
sensor information should be broadcast. During the installation of
transponders on participating ships a clarification of this regulation was
received from the USCG. It stated that the USCG intends to make broadcast of
this information mandatory if such sensors are already installed on the ship.
Integration of AIS in the Bridge Systems of the
participating ships was not achieved. The hurdles were too high. The STN Atlas
Bridge Systems on VOLENDAM, ZAANDAM, INFINITY and SUMMIT and the Sperry Marine
‘Voyage Management Systems’ (VMS) on VISION OF THE SEAS and RADIANCE OF
THE SEAS were simply not ready to accept AIS information and display it on the
Bridge System’s Radar and ECDIS. Standalone NaviSailor ECDIS was used
instead of Bridge Systems’s radar and ECDIS to display AIS information on
participating ships.
RADIANCE OF THE SEAS could not participate in the test of
AIS for this reason.
Another lesson learned is that Bridge System Manufactures
would rather sell their transponders rather than connect their Bridge
System with a third party transponder. Some manufacturers will set up
insurmountable hurdles for this connection even though it is the subject of an
internationally agreed standard for all seven layers of communication. These
IEC standards prescribe the communication all the way from the bottom-layer
physical definition to the top-layer application protocol and message content.
This was the reason why SUMMIT and INFINITY did not
participate in the test of AIS.
At the start of the test it was noted that the NaviSailor
was receiving many unintelligible messages. Receipt of each of those was
accompanied by an alarm, which made it difficult to work with the ECDIS
system.
The source of the messages was traced to the
environmental data that were being transmitted by a transponder at the Delta
Port terminal. It sent out updates for wind, current and tide every 10
seconds. The NaviSailor processed these binary messages as regular text
messages resulting in the false alarms for receipt of an incoming message.
Transmission of the environmental conditions at Delta
Port was stopped until a new build (#5740) of NaviSailor 3000 software that
ignores the messages could be developed and installed on participating ships.
There are no internationally accepted standards for
messages describing environmental conditions. This poses a problem for AIS
Information Display Vendors, as they have to write separate interpreters for
every region in the world that defines its own message structure and protocol
for environmental conditions.
1.
Overall Impression
VISION
OF THE SEAS Bridge Team
Pros
The
benefits of displaying AIS targets on Chart or Radar are clear.
-
It
can lead to safer navigation if used in the appropriate manner.
-
It
will ease identifying SOLAS ship traffic in order to make appropriate
passing arrangements.
-
It
can be used as a secondary source of information along with the ARPA for
collision avoidance
Cons
ZAANDAM
Bridge Team
AIS
Pro’s:
-
Will lead to safer navigation if used in the appropriate manner.
-
Gives a lot of information needed to make proper collision avoidance
decisions.
AIS
Con’s:
-
Too much information can lead to confusion.
-
System on the ZAANDAM proved to be inconsistent.
2.
Timeliness and Quality of AIS versus ARPA Information
VOLENDAM
Bridge Team
AIS
targets were acknowledged to react much quicker to a change in course for
instance that ARPA targets. Also AIS targets don't 'swap' or disappear in
shore radar echoes.
ZAANDAM
Bridge Team
In
Glacier Bay we measured the distance between the ARPA and the AIS target icon
both of the DAWN PRINCESS. It was about 3 cables, which the Bridge Team found
unacceptable. The AIS target was correct, the ARPA was not.
3.
AIS Reliability
VOLENDAM
Bridge Team
AIS
was found to be quite reliable and especially useful to identify targets in
radar blind spots. When DAWN PRINCESS followed VOLENDAM through Seymour
Narrows, she was in VOLENDAM's Radar blind sector, however, DAWN's AIS target
presented itself on screen consistently and reliably.
a)
Range inconsistent
VISION
OF THE SEAS Ron Holmes
Sometimes
when rounding Rocky Point North bound we can see the Zaandam south bound in
Lynn Canal on the AIS before it becomes visible. This is handy. At other
times, we are around the point and in plain sight of the Zaandam at 15 miles
or so and the AIS sees nothing until 12-13 miles out. It is inconsistent in
range abilities so does not become a reliable tool, just a handy one when it
is functioning correctly.
VISION
OF THE SEAS Andres Holmgren
We
have had a very different range spectrum than Volendam experienced. From 30 NM
to just a few miles. The times we had good reception it was a good tool for
all of us.
b)
Connection with ECDIS inconsistent
ZAANDAM experienced intermittent problem with the
connection between the transponder and the NaviSailor ECDIS.
These problems continued at least through October 20th after
it’s dry-docking
Bridge Team recommendations for improvement of AIS can be
summarized as follows:
Following are the recommendations that, if adopted, would
make AIS a valuable aid to navigation. Excerpts from the debriefing minutes
that relate to the topic follow each recommendation.
1.
Require Boats to carry AIS
Regulators
and Coastal Authorities should require boats that are longer than 20m to carry
AIS.
2.
Reduce cost of Class ‘B’ transponders
Regulators
should minimize the barriers that prevent Non-SOLAS ships from carrying a
transponder. Specifically, regulators should simplify the technical
requirements for Class ‘B’ transponders, for instance by eliminating the
requirement that they operate on VHF Channel 70 and by limiting frequency
agility to only the higher frequencies close to AIS1 and AIS2. This will
significantly reduce the component and production costs of Class ‘B’
transponders.
3.
Rebroadcast ARPA Targets
Coastal Authorities should broadcast ARPA targets
of ships and boats that don’t carry AIS and are longer than 20 m LoA. Such
‘virtual’ AIS targets should at least include the name and callsign.
VISION
OF THE SEAS Bridge Team
All
vessels need to have transponders. They possibly should be segregated into two
or three groups:
This
would give the operator a clearer picture of any development of close quarter
situations and it will enable more rapid identification and communication with
conflicting traffic.
Pilot
reaction has been mixed but mostly very positive. The Pilots agreed
overwhelmingly that all vessels, especially fishing vessels, should be
required through regulation to carry transponders.
VISION
OF THE SEAS Ron Holmes
All
in all in is a nice system with many good uses. However, it would be 1000%
more useful if the vessels not participating in traffic schemes were required
to have transponders. This would include but not be limited to Fishing vessels
and Small commercial Vessels such as day trip pax vessels and towboats. I have
only used this in Alaskan and B.C. waters and in these areas we have had
Pilots on and/or were participating in a traffic management scheme. Therefore,
we knew the large vessels in the area and did not need to ID them. It is the
small vessels, especially the commercial Fishing Vessels that interfere in the
safe navigation of the vessel. It would be a wonderful deterrent if they were
easily identifiable by name. This would cut down on dangerous crossing
situations and make calling the correct vessel when needed while sailing in an
area of several Fish boats much easier.
VISION
OF THE SEAS Andres Holmgren
My
personal opinion is that the AIS-system has to be implemented on all size
vessels until it can be really useful for merchant marine vessels. Until then
it can only be used as an extra help in navigation and not as equipment that
you should trust fully upon.
VISION
OF THE SEAS Gustav Andersson
Usually
it has been with the “small boats” that we have the problem. The big ships
are carrying pilots, we all know in advance what ship will come around the
corner and we have the VTS to report to. The smaller crafts are not
participating in any system and therefore a hazard us. On the other hand, what
info can they transmit, what equipment do they have. GPS to send Pos, COG and
SOG, but nothing else.
ZAANDAM
Bridge Team
Problem
ships in Alaska are the small vessels and those ships are ones who do not have
AIS. Rules of the road should be followed at all times. Fishing boats should
have AIS too.
This
recommendation was given in point A.3 above. It is repeated here for a
different reason. If APRA targets are re-broadcast then it will allow the OOW
to unambiguously associate ship names mentioned in VTS traffic advisories with
targets, thus improving situation awareness. The same is true for other vessel
traffic related VHF communications, either between VTS and a ship or between
ships.
VOLENDAM
Bridge Team
The
Bridge Team would prefer if VTS rebroadcasts ARPA targets of ships over 20 m
LoA that do not carry a working AIS transponder. Such re-broadcasts should not
only include ARPA information about Position, COG and SOG but also and most
importantly the name of the vessel. Doing so will improve the OOW's
situational awareness not in the least because VHF traffic can be associated
with the target of the ship that is transmitting.
Terry
Sampson (Canadian Coast Guard, VTS Vancouver) commented that identification of
ARPA targets by VTS operators is not fool proof and that sometimes ARPA
targets' labels are swapped.
VISION
OF THE SEAS Gustav Andersson
It
would be a tool, but again it’s not the VTS liability to ensure that the
info is received correct.
ZAANDAM
Bridge Team
Also,
VTS should transmit its ARPA targets of ships > 20m that do not carry an
AIS transponder.
Bridge Teams feel that AIS information should be part of
the Integrated Bridge System (IBS) because it is unsafe to require the OOW to
watch a separate AIS screen as well as the (multiple) Radar and ECDIS screens.
Too much of the OOW’s time would be required to interpret and assimilate AIS
target information presented on the AIS screen and then associate it with
visually observed targets and with ARPA target information presented on other
screens. This is too distracting and could make AIS a deterrent rather than an
aid to navigation.
A three line ‘Minimum Keyboard Display’ of AIS
information was felt to be unacceptable.
The resulting recommendation for Manufacturers of
Integrated Bridge Systems is to allow a Ship Operator to upgrade the software
of an existing Bridge System at a reasonable cost so that it will display AIS
information on the systems’ Radar and ECDIS screens.
The resulting recommendation for Regulators and Competent
Authorities is to require SOLAS ships to integrate AIS information in existing
navigation screens and disallow setting up AIS as a separate stand-alone
(black) box with a 3-line display.
VISION
OF THE SEAS Andres Holmgren
There
was no integration between the two systems (AIS on ECDIS and the Integrated
Bridge System) on Vision. One good thing would be if the AIS targets could be
fed into our VMS (Integrated Bridge System).
VOLENDAM
Bridge Team
The
Bridge Team appreciated that AIS information was integrated in ECDIS but would
very much prefer to have the option to, also, show AIS targets on the active
Radar. The Leica GPS/AIS display although useful for a listing of AIS targets
wasn't felt to be useful in assessing the traffic situation mostly because it
doesn't relate AIS targets with Radar targets. Simon (Navigator, VOLENDAM)
indicated that for situational awareness purposes the ECDIS rather than
the Radar is used because it not only shows nearby traffic it also shows it in
the context of the relevant navigation chart.
ZAANDAM
Bridge Team
The
Bridge Team on the ZAANDAM wondered if there is an option to show the
AIS-targets on the radar screen, with an option to select which information to
show. STN-Atlas has this option. Why is it not available? AIS information
should be displayed both on radar and on ECDIS. Close-quarters navigation is
done with the radar. AIS needed on radar to show ship names.
1.
With VTS
Bridge Teams feel that it is desirable to minimize VHF
traffic because it reduces the number of things the OOW has to focus on. Thus
an AIS-equipped ship should not be required to report its particulars, nature
of its cargo, destination, position, etc. because AIS was designed to do this
without Bridge Team involvement. Bridge Teams, however, recommend that VTS
personnel continue to provide traffic advisories. These advisories are needed
by ships that do not carry AIS as well as by those that are, to improve
situation awareness.
To further reduce VHF traffic it may be desirable for VTS
to replace traffic advisories that are currently communicated to each
individual ship with generalized traffic advisories, especially if VTS
re-transmits ARPA targets via AIS. Such traffic advisories for AIS equipped
ships should to focus on the intentions of nearby traffic.
It may be desirable to also ‘publish’ a ‘Traffic
Control List’ of nearby traffic including each ship’s name and intentions
and use AIS to continuously update this list, much like the lock-through
schedules published by the St Lawrence Seaway VTS.
The resulting recommendation to Coastal Authorities is to
eliminate call-in points after an initial VHF communication to verify and
confirm that AIS information received by VTS is correct and up to date.
Another recommendation for Coastal Authorities,
Regulators and manufacturers of AIS display systems (IBS, Radar, ECDIS) is to
allow Bridge Teams to evaluate the merits of a ‘Traffic Control List’
(continually updated list of nearby traffic).
VISION
OF THE SEAS Bridge Team
During
the test Vancouver VTS (MCTS) operators we not able to see AIS targets. The
Team doesn't think it will affect VHF traffic with VTS because it will still
need confirmation of nearby traffic.
VISION
OF THE SEAS Gustav Andersson
It
is not the VTS responsibility nor liability to make sure that ships make
arrangement to clear each other and what confirmation does the VTS have that
the OOW has received the advise?
VOLENDAM
Bridge Team
He
(Simon Westall, Navigator, VOLENDAM) does expect that VHF traffic with VTS
operators will be eliminated because all information that is currently relayed
via VHF to VTS operators is being by transmitted via AIS. Even advisories from
VTS operators should be transmitted as (addressed or broadcast) AIS messages.
This reduction in VHF volume is expected to enhance safe navigation because it
reduces the number things the OOW has to focus on.
ZAANDAM
Bridge Team
Ship
to VTS reporting should be eliminated, however VTS operators still will need
to provide traffic advisories
2.
With other Ships
Bridge Teams expect a significant rise in ship-to-ship
VHF traffic because AIS will make it possible to address a target by its name.
The resulting recommendation is for Marine Training
Institutions, Regulators and Coastal Authorities to emphasize the importance
of adherence to COLREGS and the need for the OOW to focus on watch standing
rather than answering superfluous VHF calls from other ships and boats.
Also, Regulators should prohibit and Coastal Authorities
should enforce a prohibition for small boats to contact a SOLAS ship via VHF
in congested areas when there is no safety reason to initiate the contact.
VISION
OF THE SEAS Bridge Team
Inter-ship
VHF traffic volume is expected to rise significantly.
VOLENDAM
Bridge Team
Simon
(Navigator, VOLENDAM) expects that AIS will cause inter-ship VHF traffic
volume to rise rapidly with the introduction of AIS just because AIS makes it
possible to hail a target by name. He expects that VHF traffic volume will
subside after everyone has gotten used to AIS.
VISION
OF THE SEAS Gustav Andersson
Do
not agree…. The chat on the VHF will not stop, because instead of using the
Colregs vessels will talk to each other that they will use the colregs,
“just to be sure”
ZAANDAM
Bridge Team
The
bridge team believes that VHF traffic will increase. Knowing the name of a
ship will make it easier to call and therefore we do have to be cautious not
to use the radio too often.
Bridge Teams feel that having a ‘Transit Schedule’
for a Gateways such as a narrow channel, a lock entrance, a bridges or a cape,
will allow them to anticipate traffic rather than having to react to it, thus
improving safety.
Such a ‘Transit Schedule’ should be a list of ship
names in sequence of their assigned or estimated transit sequence. This list
should be continuously kept up to date through AIS.
1.
Published by VTS
The transit sequence should be assigned by VTS who should
also communicate the list via VHF to ships that do not carry AIS. Gateway
Icons should be clearly displayed and positioned at the ‘Gate’. Selecting
this icon should open the transit sequence schedule.
VISION
OF THE SEAS Bridge Team
The
team felt that it would be useful to have lock through schedules and transits
through narrow passages and around capes available upon selection of a base
station, but only if a (shore-based) authority controls the sequence of
transits.
VOLENDAM
Bridge Team
Waterway
Condition messages about traffic should list the ships transiting through the
'Gateway' (Narrow Channel, Lock Entrance, Bridge or around a Cape) sorted by
their Gateway Transit Time and listing their name range and bearing.
This
information should be maintained and updated regularly. It should originate
from the local VTS or, in the absence of a VTS, from ships that are
approaching a Gateway.
To
make the latter possible it would be very helpful if an (un-manned) AIS relay
station was set up near each Gateway to increase the range and thus the period
during which transit sequence arrangements can be negotiated between ships,
published on the 'bulletin board type' list and acted on by adjusting
speed/Gateway ETA. This 'do-it-yourself' approach to VTS is expected to become
a major benefit of AIS. Currently, for Seymour Narrows for instance, such
Gateway transit sequence arrangements are made by the pilots using the cruise
ship schedules that are published months in advance. These arrangements, by
necessity, exclude transit sequence arrangements with other ships passing
though Seymour Narrows.
ZAANDAM
Bridge Team
A
continuously updated transit schedule, for example through Seymour Narrows,
will be very useful as a submenu option.
2.
Using ETA’s
If no VTS is available, Bridge Teams felt it to be
unrealistic to expect ships to negotiate transit sequences between themselves.
Thus, if no VTS is available, the transit sequence should be based on each
ship’s automatically calculated ETA at the ‘Gate’ using current VMG
(Velocity Made Good towards the Gate) and remaining distance. The position of
the Gate should be selectable by the OOW. The Transit Schedule should include
ETA’s of ships that are not equipped with AIS. The latter’s ETA’s should
be based on their (ARPA target’s) VMG and remaining distance.
3.
Extend AIS range through Relay Stations
Bridge Teams felt that they could better anticipate
traffic if AIS range were to be extended by Relay Stations especially near
Gateways. Such stations would ensure that Radar blind spots near Gateways
would be filled in with AIS targets.
If Relay Stations were also equipped with Radar then they
could also be used to transmit the ‘Gate’ Icon and publish the
automatically updated Transit Schedule of all traffic via AIS.
Bridge Teams feel that AIS information received directly
from a target should supersede AIS information received through a Relay
Station.
In light of the above Bridge Teams recommend that:
