Notebook

Internet at Sea – the W25

2009-10-26T00:14:27Z

A few friends have asked about the Wireless Broadband Internet and phone setup aboard Te Moana. Last year, we fitted an Ericsson W25 on our boat. Previously, we had USB modems (Maxon CDMA and later the Maxon Turbo modem) with Telstra mobile data plans. Today I still use the (orange) Maxon Modem while we're ashore (handy in the train or at a customer). But while on the boat I take the SIM card out of the modem and plug it into the Ericsson W25 which Andersen Marine installed on Te Moana last year.

Installation

As part of the installation, Marty Andersen installed a high gain antenna atop of Te Moana's mast with low loss (fat) cable down to the W25. We found a spot for the W25 at the base of the mast, minimizing the cable run and the power losses.
We bought a standard telephone at Dick Smith, which was installed at the Navigation table and wired to the W25 telephone connector.

Configuration
Our original modem was from Telstra Mobile (as opposed to from Telstra BigPond). This means that it has a telephone number. Using its SIM card with the W25 means it can operate as a standard (mobile) telephone.

Along the way I programmed that SIM to divert calls to my personal mobile when not answered. To program the SIM, put it into a normal mobile phone handset and set forwarding up.

Of course the really useful aspect of the W25 is its wireless router. My computer and mobile phone use the boat's wireless internet access automatically when on board.

Performance
We've experienced excellent coverage from this set-up over the past year with flawless reception all the way along the NSW coast. The only glitch was on a hot day last summer when the temperature on the boat was well into the forties. The W25's internet access dropped out and only came back when the temperature dropped. Overall, we've been very happy with it.

I'm aware that some yachties have installed Antenna booster on their phones/modems. Personally, I have not seen the need for one with the set up which we have in place. Beside the fact that it's illegal to own one.

By the way, I'm no particular fan of Telstra, but their Next G Mobile Phone network gives superb coverage along most of the coast of Australia. Don't use any other carrier.

Alternatives
Ericsson now have a newer, smaller unit on the market, a W35 with similar features and it is a few dollars cheaper.
Maxon just launched a similar unit, the Maxiport, which uses VOIP (Voice Over Internet Protocol) to deliver telephony services.
Netcomm is now distributing a Sierra Wireless unit, the PinPoint X , which doesn't have wireless support, but does have a built-GPS unit (which I would have some use for).

AIS Class B coverage limits

2009-08-01T06:27:53Z

I'm very interested in the use of AIS on yachts, and not just as an aid to navigation, but also as a way of tracking boats. There is now a proliferation of websites which "aggregate" AIS transmission from boats and plot their position on a map. Probably the most popular of these is MarineTraffic.com, which I have written about earlier. At first glance, that would make a terrific way of tracking cruising yachts along our coast. But is it?

Last weekend's Sydney to Gold Coast race provided an opportunity to see the difference between class A (commercial shipping) and class B (leisure vessels, work boats) versions of AIS as a couple of the boats in the race carried AIS transponders. Here is what I found....

Around mid morning, Joy and I took Te Moana to near the race's rhumb line, around 8 Miles off Barrenjoey. We enjoyed a quiet lunch on the glassy seas and the winter sun. Meanwhile, as participating yachts struggled to get out of Sydney Harbour in the light conditions, I was delighted to see two of the competitors, Scarlet Runner and Imagination using class B AIS responders. I monitored their progress on marinetraffic.com and was pleased that it did a good job putting them "on the map". Certainly, it provided a much more timely and accurate position for them, than the CYCA race tracker (which was no surprise).

I was less impressed with the effective range of their AIS transponders (mind you, I don't know the make or installation details of the units used by either boat). Here is the plot created by Imagination, showing it was out of range (the uninterrupted straight line) between Palm Beach and Port Stephens. Significantly, the repeater at Newcastle did not pick up either Scarlet Runner or Imagination, while ships with class A transponders were clearly present and visible in the same area. 15NM appears to be the limit for Class B AIS. Vessels carrying class A will have a larger range because of a better positioned, dedicated antenna and the higher power output of Class A devices.

Coverage of class B boats on sites like Marine traffic can be improved by having more shore based repeaters, but it is unlikely that boat signals will be reliably picked up when more than 15 mile offshore, no matter how many repeater stations are dotted along the coast.

The moral of the story then, is that AIS is a terrific on-board navigation resource, but it cannot provide the kind of yacht tracking which many of us would welcome, automatically keeping track of cruising boats along the East Coast of Australia for family and friends. And that's even before we look at spoofing and spamming, about which I'll write another time.

Google Latitude disappoints

2009-07-26T05:30:29Z

We went out on Te Moana yesterday to check out the Sydney to Gold Coast fleet as they passed Broken Bay. It was a gorgeous day apart from the fact that there was no wind. So we parked ourselves near the race rhumb line, killed the Volvos and just waited for the fleet to crawl towards us.

I kept myself entertained playing with various yacht tracking technologies. I'm eagerly awaiting the day when we can use 'off the shelf' economical systems to track yachts, rather than clunky, expensive satellite transponders or cheap but error prone manual systems.

Every since the 2nd generation iPhone was launched last year, users can determine their location through the built-in GPS (the blue dot marks our position off the coast on the Google Maps iPhone display),

Recently, Google has been promoting its "Latitude" service, where you can share your location with your friends. This works by allowing your phone to transmit its location to the Google service, but...

There are two ways to determine where a mobile phone (and its user) is located, either by determining which cell tower the mobile phone is using (and triangulating between them) or by using the phone's built-in GPS, if it has one.

Google announced the iPhone version of Latitude last week, so I was keen to try it out on the boat. Could we track boats by simply having an iPhone on board? The answer is no on two counts.

Firstly, positions are only taken while the Latitude page on the phone is open (it is not kept up to date when doing something else with the iPhone or it's asleep).

Even more challenging is that it doesn't seem to be using the built in GPS, but insists that we're on land near a cell tower..... Ahoy Google, Ahoy Apple, not good enough.

Tracking your boat just got even easier

2009-07-19T23:01:26Z

We've been tracking yachts on this site for almost 4 years. Over the coming year, we're expecting to introduce more ways to conveniently track your boat. Most of those features assume internet access while at sea. But we're not forgetting internet deprived boats. From today, we're starting a trial allowing users to submit position reports by mobile phone. You'll still have to register your boat as per usual (here's how), but to submit a position report, you can send us a SMS text message in the following format:

date time latitude longitude comment

for example:

D20090731 T1230 S33 39.387 E151 18.169 <Did our best to secure the boat with the onset of the seasonal Westerly winds>

Notes

Separate items with spaces no special characters other then the <> brackets around the comment text.
D(ate) in year month day format as one number
T(ime) in 4 digit 24 hour clock notation
S or N to denote latitude in degrees and decimal minutes (separated by a space)
E or W to denote longitude in degrees and decimal minutes (separated by a space)

To start the service, register as normal and email "skipper at skipr dot net" with the phone number you'll be using to submit reports.

Introduction to AIS

2009-07-18T01:50:27Z

AIS stands for Automatic Identification System, a marine system which identifies a ship to others in its immediate vicinity. It does that by continually transmitting a ship's position, course and call sign on dedicated VHF radio channels.

The information of adjacent ships is picked up by the receiver section of an AIS transponder (or dedicated AIS receiver) and can conveniently be displayed on a chart plotter or other display device. The system has been mandatory on commercial shipping (over 300 ton) since 2004. In recent years,a version (AIS class B) has become available for leisure craft and other non-SOLAS vessels.

When venturing into major shipping lanes or passing busy ports, it ranks as essential safety equipment for cruising boats. With lower cost class B equipment, it is now practical to equip cruising yachts and fishing boats with AIS transponders. That will be invaluable when visibility is poor and at night. And, as adoption increases, there is a real opportunity for wider applications such as keeping track of a cruising boat by family and friends through the use of repeater stations and tracking websites like Marine Traffic.

Rather than explain AIS in all its intricacies here are some links which describe most aspects of AIS.

This PDF by Digital Yacht has an excellent overview of AIS
The Wikipedia entry for AIS describes much of the detail, although it is a bit "light on" regarding Class B systems for recreational vessels.
The US Coast Guard has an excellent set of AIS pages explaining most aspects of the system.
Bosun's Mate provides a concise technical description.

Sailing with an iPhone

2009-06-12T04:38:04Z

Regulars will know that I'm a fan of the iPhone at sea. Even without specific iPhone apps, the ability to adequately browse standard websites make so much sailing related information available at sea and with the built-in GPS (and now a compass), the iPhone is a great backup to other systems on a boat. And it makes phone calls as well...

Panbo, "the Marine Electronics Weblog" (an excellent source of marine geek news) just published a survey of current iPhone apps which extends the functionality of an iPhone on board even more. But wait....can you get Australian mapping for all these nifty chart plotting apps? Not likely.

You see, there is no copyright on US charts, as the US statutes prevent their Government claiming copyright on works which were created by Government employees. That's why software makers can include (raster) charts at no charge.

I think you could make a good case for abolishing copyright on Australian Hydrographic charts. Having free raster charts available would encourage more boaters to have up to date charts and encourage the use of low end systems such as those in the survey above as standby systems and on small craft. How about it, Kevin?

And Caroline, next time you talk to Mike Prince at the Australian Hydrographic Office, ask them why they don't freely license Australian charts which we, in effect, have already paid for through our taxes.

Planet Skipr mailing list

2009-04-16T01:03:49Z

Just in case you were wondering where it was... The Planet Skipr mailing list had gone AWOL and it took a while to get it up and running again. It looks like it was associated with the recent addition of the mysailing.com site. I've taken mysailing.com off and subscribers saw a long email this morning with the news from the past week.

You don't know what I'm talking about? Planet Skipr is a once a day email with short news items of interest to the cruising community, gathered from a variety of sources. You can subscribe to the Planet Skipr mailing list or read more about it.

[Update - There is a continued issue with the Planet Software - sorry - we're working on it]

Keeping up to date

2009-03-13T02:29:17Z

I've been adding some items to the Skipr website and finding new ways for folks to be kept up to date.

Resource Pages
We recently added a page with cruising guides and one with useful links. They are primarily for those cruising North this winter, but should be useful for others as well. You'll find them in the right hand margin of this page, under "Ports & Anchorages".

New Mailing List for heading North
Apart from the TurnLeft mailing list which we just started, don't forget about the Planet Skipr mailing list. It collects stories from this site and adds them to headlines from sail-world.com. You receive everything that's happening in one email per day. Now that Cruising Helmsman is publishing some of their articles online (via My Sailing), I've added them to the system, so you'll see their headlines as well in the "Daily Planet". If you're not already getting them, subscribe here.

Twittering
You'll see increasing mention in the press about Twitter. While to the uninitiated, it might sound like yet another techie obsession, check it out. The idea is to write short entries about "what you 're doing now". Others can easily your activities and you can follow others, so it encourages social interaction. For example, I have a @skiprdotnet account on twitter where I write whenever I add something to this site. I also have an account for @TeMoana, where I write about what we're doing on the boat.

I'm working on an extension to the Skipr boat tracking service to (optionally) send a message to a twitter account whenever a position report is entered. It would allow anyone with their Twitter account.

Turn Left - a Cruising Mailing list

2009-02-13T22:19:36Z

We've set up a new mailing list to encourage "a conversation" between those of us hoping to sail North this winter, have done it or just dream about it.

To join, go to the registration page or simply send an email to "skipper at skipr dot net".

After you join, please send an introductory message to the list and make yourself at home. Blatant commercial messages are discouraged. We welcome any messages about your travels, experiences, problems and solutions, associated with sailing up and down the Australian coast line.

Maritime meeting notes and more

2009-02-13T21:02:28Z

Here is an interesting account of a meeting at the Balmain Sailing Club (website) attended by NSW Maritime. It covers the use of mooring, anchoring in the harbour and various contentious issues (such as whether you can pee overboard). An excellent account which will settle many a sundowner discussion. Download the Meeting Account here (PDF).

By the way, there is another interesting document on Radio Communications at the Balmain Club's website, written by Allan Adolphson for a cruise to Hobart in 2007. A very comprehensive guide, good to have on board. Download Allan's Guide (PDF).

Definitive listing of VMR stations

2009-02-09T19:28:11Z

Now that there is to be improved coordination between the Coastal Patrol and Coast Guard flavours of Volunteer Marine Rescue organisations, we now have a definitive list of VMR stations in NSW on the Coastal Patrol Website. Unfortunately, it appears only linked from inside "New Standard Operating Procedures for more effective NSW Offshore Vessel Tracking", rather than clearly linked from the site's menu.

Because of the way the Coastal patrol site was designed, you can't simply save the URL of a page. As of today (10 Feb 09), here is the link to the latest VMR list (including their email addresses - Whoopee!).

I hope Coastal Patrol doesn't change this URL every time the list gets updated. I'll try and keep the link up to date, please leave a comment if the link appears broken...

Disposing of Flares (Afloat)

2009-01-29T20:26:44Z

It's an old one but a goodie... How do you dispose of out-of-date distress flares? Robin Copeland in this month's (Feb 09) Afloat, has an editorial about disposal methods - finding no really practical options. Walking into a Police Station with wide eyes, saying "look what I just found" will probably work...

The best option I have found to dispose of flares is as part of a safety-at-sea course or exercise which are regularly held by sailing clubs like the RPAYC. It gets you experience in activating them, as well as giving an opportunity to dispose of unwanted flares.

By the way, great magazine, Afloat. Great price, Good value. Did you know that you can read it online? You can safely subscribe to their email - no spam - just a monthly email with a list of articles - recommended.

Marine Traffic website

2009-01-22T20:40:10Z

Marinetraffic.com falls in the category “why wasn’t I told about this before?”. It aims to plot all ships carrying AIS and uses volunteer ground stations. Stunningly simple concept (connect AIS receiver to a computer and upload AIS data to a central site)

Here is the state of shipping going to and from (and anchored at) Newcastle this morning:

Clicking on a vessel displays its details:

Wow…. Try it out.

Coverage is not complete (it needs a station in MacKay for example) and of course this is not a system on which yachties would want to rely on exclusively, but its yet another reason for having internet access on board. And a sensible resource for those as yet without our own AIS.

The shape of things to come.

Cruising the South Pacific with the Island Cruising Association

2009-01-13T23:09:37Z

by David McKay

Andrea and I sailed our 48 foot steel Van de Stadt yacht "Diomedea" amongst the islands of the South Pacific during the winter of 2008. After leaving Sydney to cross the Tasman Sea in April, Diomedea arrived in Opua, Bay of Islands where we met John and Lyn Martin, directors of the Island Cruising Association. We had joined the ICA so that we could participate in a rally from New Zealand to Tonga in May.

We were provided with a wealth of information and support prior to departure from Opua, including seminars on weather, safety, passage making, boat preparation and so forth. Membership of ICA also provided significant discounts on chandlery and other purchases. Our clearance out of NZ was made very easy and quick. Duty free food, alcohol and fuel purchases were facilitated.

We arrived in Tonga some 6 days later and anchored at the beautiful Pangaimotu island near the capital of Tonga. All clearing in procedures were done very speedily on the island as opposed to having to tie up to the filthy, rough and rat infested docks of the harbour. The ICA had organised for the officials to come to us. A series of social events allowed us to begin establishing friendships that would last for the next six months and some of them for much longer. We also soon learned of the skill base available in the fleet of 20 yachts, giving us a sense of security should things go pear shaped. Cruising through the archipelago of Tonga was done independently for all participants but the option of meeting up at various anchorages was always available if desired. There was no fixed agenda when "in country". Real insider advice pertaining to the islands was given during chart marking sessions

As we had to meet friends in Fiji, we left Tonga independently and what had now become the Pacific Circuit Rally followed us about a week later. In Savusavu, the rally organisers gave us a one hour practical on how to do "sevusevu" with local chiefs in the villages we were to visit. Highly entertaining and useful. We eventually regrouped with the rally at Musket Cove in western Fiji in July, in preparation for the passage to Vanuatu. Our week at Musket Cove was marvellous with organised and impromptu social events. Group activities such as scuba diving became easily achievable. Customs clearance was again smoothed with the ICA bringing out the relevant officials to the island, sparing us the considerable bother of having to sail back to the mainland. Diomedea sailed to the island of Tanna in Vanuatu. Here, entry was streamlined by officials coming to Port Resolution rather than us spending a ghastly day bouncing in the tray of a 4WD across the island. We then had a marvellous cruise the length of Vanuatu, sporadically meeting rally boats at delightful tradewind anchorages.

The jewel in the crown of ICA organisation was yet to reveal itself however. With the rally increased to 39 boats, we departed Port Vila for the island of Ouvea 180nm away in the French Loyalty group of New Caledonia. Ouvea is not a clearance port but for us it all happened and we could stay at this, the most beautiful of all South Pacific destinations. Normally cruisers have to go to the capital Noumea, 2-3 days away. Those wishing to cruise Ouvea and nearby islands then have to make the return trip. Alas, our stay in French waters was limited and time came for Diomedea to return to Australia. We said our farewells to our friends and had an easy five day passage from Noumea to Coffs Harbour, arriving in early October. Those that remained in New Caledonia cruised around the Grand Terre and then down to Ile de Pins before heading for either New Zealand or Australia. The leg to New Zealand was an "All Points" rally with cash/goods prizes at the end.

The mix of yachts in the rally was interesting. About half were NZ registered. Of these, most were just having six months off but some were using the rally as a springboard into their world circumnavigation. Of the other half, a few were from Australia. The rest were from all over the world, having arrived in NZ as part of their ongoing circumnavigation. Boats from the UK, Europe, US were well represented.

Whilst one could do this entire cruise independently, Andrea and I felt that the "cruise in company" method worked particularly well. At an organisational level, a great deal of time and angst was saved. Costs were reduced in many areas. Advice and support was readily available and made many things achievable for us, being relative novices to cruising in these waters. Personally I learned a great deal from John and Lyn as well as from other rally participants. The camaraderie was fantastic. One night, Diomedea came into Havannah harbour after a 75nm leg to windward in 25 knot winds. Rather to our surprise, a dinghy from one of the rally boats quickly appeared at our stern and we were whisked over for a BBQ that was already in progress. The perfect coda for a hard day's sailing. We partied until late before a good sleep.

Would I go with Island Cruising Association again in the future? Absolutely. Was it cost effective? Beyond doubt. Was it fun? You bet.

Details about ICA can be found at: http://www.islandcruising.co.nz

Their rally program is available for 2009.

See our blog for more pictures from our trip: http://www.sailblogs.com/member/diomedea/

David and Andrea McKay are medical practitioners based in Sydney. Diomedea is their second yacht and has previously done trips to Lord Howe island, Flinders island in Bass Strait, along the coast as far as the Whitsundays, as well as competing in the 2005 Sydney to Hobart race.

AIS with Crystal Blues

2008-11-01T04:14:16Z

The following is a description of the fitting of an Automatic Identification System (AIS) Transponder to SV Crystal Blues by Neil and Ley Langford. It originally appeared on their web site.

AIS Part 1 - A Primer

My father taught me to sail when I was about 8 years old - he's the worried one in the old photo at right (probably because my brother Peter is on mainsheet). With great and delightful understatement, he always said that "a collision at sea can ruin your whole day". He's absolutely right of course, though nowadays we can use AIS technology to help avoid those "ruined days". This is the first of three posts regarding the system, and basically describes the technology. Future posts will cover our installation experiences and the system in operation.

Some years ago the International Maritime Organisation (IMO) ratified a standard requiring all ships over 300 tons to carry an Automatic Identification System (AIS) transponder. This was a major step forward in collision avoidance for ships at sea. The system really works - AIS equipped ships constantly transmit information including name, MMSI number, position, speed, course, rate of turn, cargo carried etc etc. Commercial vessels within range receive that data, which is then displayed on dedicated screens or (in most cases) overlaid onto radar or chart plotting screens. The result is that AIS equipped vessels are readily identified, tracked and avoided.

This is a significant primary safety system, and many in the yachting community have taken advantage by purchasing low cost AIS receivers - these display ship locations on navigation chart plotters, or on suitably equiped navigation computers. Whilst an AIS receiver system is a good thing to have, I always believed that the best safety system required the big ships to see me as well - I wanted a transponder that would transmit and receive.

Nowadays we can all see and be seen, with low cost AIS transponders available to the cruising and pleasure craft community. The "big ship" Class A systems are expensive, so the IMO has also ratified a simpler version called AIS Class B, for pleasure vessels.

There are important differences between the two, however they are designed to work together. Class A systems use dedicated GPS receivers for position information and system timing. They then transmit a wide range of vessel data, and do so quite frequently, using coded data bursts on VHF channels 87 & 88. The system uses a protocol called SOTDMA to keep everything organised, with GPS derived time managing the broadcast slots. With 2250 time slots on each channel every second, the dual channel system provides up to 4500 time slots. Class A systems transmit at up to 12.5 watts. A ship travelling at more than 14 knots will transmit dynamic data every 6 seconds. A course change increases the burst rate to every 2 seconds.

Thats us in the chart plotter image at right, the black circle and arrows on the lower right, moving west. At left of the image are AIS equipped ships entering and exiting Singapore Straits, into the Sth. China Sea. Click the image to enlarge.

Class B systems also use a dedicated GPS receiver, but transmit a more restricted data set (no rate of turn, destination, ETA or cargo information) and do so less frequently, using less power (maximum 2 watts). The control protocol is CSTDMA (Carrier Sense Time Division Multiple Access). Basically the Class B systems listen for a gap in the Class A traffic, then transmit. There is no guarantee that any individual data burst will be successfull, however the system transmits a burst every 30 seconds when underway. Even in Singapore, with literally hundreds of ships transmitting close by, I've watched very solid returns from Class B equipped vessels in the Singapore Straits. The system can certainly process lots of traffic - our transponder identified over 1000 targets (!) in 48 hours on our recent passage from Singapore to Langkawi.

Most of the approved Class B systems use a common internal circuit board, made by Software Radio Technology (SRT) in the UK. SRT was part of the IMO advisory panel that set the standard, so its no surprise they have complying product on the market. Our Comar CSB200 AIS transponder (user manual here) uses the SRT circuit board.

AIS is already compulsory on pleasure craft in some parts of the world (eg South Korea), and I believe it will become mandatory in many countries. In Singapore, pleasure craft must carry either an AIS-B transponder or one of the local HARTS transponders that use cellphone technology as the data link to shore based monitoring stations (more info on HARTS is here - thanks to Terry Sargent on SV Valhalla for the document).

For more background information on the politics, technology and products behind AIS, I suggest you spend awhile reading the AIS links on the excellent PANBO blogsite here. A very good background story, published by Yachting World, is also available here. Our own installation experiences will be posted next.

AIS Part 2 - The Installation Experience

AIS stands for Automatic Identification System, an active primary safety system for vessels at sea. The black arrow in the photo at right, captured from our PC screen, is Crystal Blues. The red arrows (targets) are ships we want to avoid. Clicking on a target reveals the data box seen at bottom left - lots of information on the ship in question (click the image at right to enlarge).

I met a cruising sailor last night who said that my first AIS story (here) was very technical - oops, I guess it is a technical subject. Not sure that I can eliminate the technicalities, but I will try to explain them. First though, an essential technology primer .... I strongly recommend you spend time roaming the excellent PANBO website, specially the AIS pages. Also, here are links for two very informative and useful documents, covering co-axial connectors and co-axial cabling. OK, on with the story ....

We purchased our Class B AIS transponder from Oceantalk in Singapore - in fact we bought four of them, as several other boats wanted to install the system. The unit is a Comar CSB.200, manufactured in the United Kingdom. It was supplied by Oceantalk with a Shakespeare VHF whip antenna and a Sanav GPS antenna.

All Class B AIS transponders require a dedicated GPS receiver and a dedicated VHF antenna. No arguments please - if you want this powerful safety system, you have to install the extra antennae. No, you cannot share signals from existing systems, however the AIS derived GPS position information is available to you as a separate NMEA signal, for chart plotting purposes. You'd better plan carefully for antenna locations, bracket positions and cable runs.

The GPS antenna is a simple patch antenna with a low noise amplifier that sends the received signals (as RF) direct to the AIS system for timing analysis - in other words, the external receiver is just an amplified antenna, and all the complex decoding and mathematical computations to derive your vessel position occur inside the AIS transponder. This is a specific requirement of the IMO AIS regulatory framework - it basically ensures that no one can feed fake vessel positions into the system. That is good to know ...

On the VHF side, AIS Class B uses just 2 watts of radiated power to send its reports outwards (the big ships get 12 watts). It is easy to receive signals from big-ship class A systems, however you better pay attention when installing your VHF cables, connectors and antenna. You want to ensure that all of your 2 watts is actually radiated into the ether. Robin Kidd from Oceantalk stressed this point - make sure your VHF cabling and connection work is good. Installation requires the following :

- Physically mount the AIS box. A U-bracket is supplied, but we used industrial strength adhesive Velcro to mount it on a vertical bulkhead (see photo).
- Run the cables for VHF and GPS antennae
- Install and connect both antennae
- Run cable for DC power with a fuse in line
- Run the data cable to the chart plotter/display system
- Terminate everything and then commission the system

Of course your chart plotter must be compatible with AIS messages in NMEA format to display the targets and information. If it isn't, you can use this very neat AIS display from Vesper Marine, the AIS Watchmate, or a more serious display (with charts) made by Comar, the CSD.200.

Back to the installation. If you power the box from a shared DC circuit breaker (ours is on our navigation instruments circuit) you should include a 5amp fuse in the power feed. Be careful with the VHF antenna cabling - OK, its just RG.58, but you've only got 2 watts to radiate, so make sure you use high quality connectors and fittings.

The GPS receiver supplied by Oceantalk is the RV-76, made by San Hose Technology in Taiwan. It includes a nice 10 metre pre-terminated cable. Its very thin, and easy to run through the boat, but it turns out to be RG.174, which has very high losses (attenuation) at these frequencies (1.5ghz). If you use the supplied cable as-is, with its existing terminations, it will work just fine. However if you need to cut, join, extend or splice (as we did), then you'll have to use a more suitable cable (RG.223). After attempting to extend the supplied cable, and getting no satellite signal, we changed to a Bedea RG.223 with Telegartner crimp connectors - voila, tons of signal. We purchased the cable and connectors from Coastal Electronics in Singapore, though similar cable is made by Belden and others. Make sure you use the correct crimping tool (see photo).

On the VHF side, the Comar AIS box will actually measure and report the SWR (reflected energy ratio) on your VHF transmission line during commissioning - you'll soon know if your VHF cabling and connectors are good or not. Click on the photo below at right to see typical values.

With all that hard work done the rest was easy - plug the box into our PC using the supplied cable and configure the COM port on the PC (baud rate etc) . Then load the Comar software (supplied) and configure the unit. At this point you'll be asked to input your vessel identifier, which is the unique "MMSI number" issued by your National Marine Authority. If you don't have an MMSI number you'd better apply for one now, because you cannot transmit using AIS without one. A Comar Class B transponder will stay in "receive only" mode until you give it your MMSI number. The real trick is that this number can only be entered ONCE by the user - mess it up and you have to send the box back to the dealer for resetting.

I've just learned that Class B systems are FINALLY approved for use in the USA (story here), but that they are not allowing users to configure the MMSI identifiers. I bet that will be fun to administer.... seems the installers or retailers will have to configure the box before handover. The Comar configuration software is simple to use, neat and logical.

So, use only good cables and connectors, get yourself an MMSI number and enjoy the results. Our next story on AIS will conclude the series with our user experiences

AIS Part 3 - Safety At Sea, with AIS Onboard

AIS helps us avoid the cruising sailors greatest danger - a collision at sea. Of course the system isn't perfect, however it is a powerful ally in collision avoidance and I wouldn't want to be without it. Our previous two stories (read them here and here) introduced the system and discussed a typical cruising boat installation - in this story we share our operational experiences.

The Singapore Straits is the busiest shipping lane in the world, and the nearby Malacca Straits are not far behind in the traffic stakes. These two waterways provided a strenuous testing ground for our new Comar AIS installation. Our very first test was conducted on a three day passage from Sarawak (northern Borneo) to Singapore. Departing Kuching, capital of Sarawak, we tracked several ships on screen that were well over our visual (and radar) horizon. We also noted a fixed AIS base station on a mountain top near Kuching, reporting itself as being highly accurate in its position. As a newcomer to AIS this puzzled me, however we could see that base station for over 100 nautical miles into the Sth China Sea, so it was a welcome reference. You can see it in this image, the purple dot near the bottom, with its own MMSI number of course.

Travelling from Borneo to Singapore there are not a lot of ships - hence not a lot of AIS traffic and therefore a great signal to noise ratio. In that low noise / low traffic environment our system was receiving and plotting ship locations more than 120 nautical miles away. It was great to know well in advance the traffic that was likely to cross our path. We also noted that military support vessels don't have to run their transponder all the time - we passed within 1/4 mile of a small fleet oiler that didn't exist on AIS - though I'm pretty sure they knew where we were, and we had her on radar for hours. Whilst military vessels have a nominated identity in the AIS world, they don't always broadcast their location, for obvious reasons.

As we approached Singapore the traffic density (and target numbers) increased, and the maximum receiving range fell off. This is a logical consequence of the increased traffic levels, and illustrates how good the system really is - when traffic is dense the closer vessels dominate - which is exactly what we want for effective collision avoidance. In this image you can see vessels arriving and departing the Straits (red & green triangles) plus anchored vessels (purple triangles).

Departing Singapore for Langkawi, we cleared immigration at the Western Quarantine Anchorage. Already we had hundreds of vessels showing on our display, but the software handled things well and it was never confusing - at all times the closest and most threatening targets were clearly visible. In a dense traffic situation (harbour / river / channel) it pays to zoom in close on the chart plotter display screen, so that only local targets are visible - the ones that matter. One hour out we plotted a Class B transponder, the first we'd seen on screen, and watched this small motor vessel cross two shipping lanes and then run past our port side. Despite several hundred Class A transponders broadcasting close by, the Class B vessel was consistently visible. The 30 second reporting frequency of Class B systems was just evident - this was a quick motor boat, and the Class B position updates were just a little lumpy.

Moving into Malaysian waters we headed north west up the Malacca Straits, estimating three days for our passage to Langkawi. This was our sixth transit of the Malacca Straits, but our first with AIS, and what a great difference it makes. Every large commercial vessel showed up on our chart plotter, giving us very early warning of their speed and course. We habitually stick to the eastern edge of the main shipping channel in the straits, hoping to keep out of the ships way and also to avoid the fish nets and fish traps that pepper the inshore waters. Passing Port Klang has always been a challenge - it's a major shipping port and many ships turn into and out of the Straits channel, but this time it was easy. This image, zoomed out on the chart display, shows the traffic density - we're the black circle and arrow in the middle. Seriously, the traffic just parted for us - ships running up the straits turned early or late and always gave us plenty of sea room - it was very clear that our AIS transmissions were being watched. What a joy. We usually keep a dual lookout in that region, one of us on port and the other on starboard, however this time it simply wasn't necessary - I slept soundly for that part of the passage. Amazingly, in that three day transit the AIS system logged over 2000 targets. That's a lot of ships.

I've always found that most commercial mariners will try to be cooperative if they have the right information - AIS certainly gives them that. More importantly, on most large vessels the voyage data recorder (info here), like the one at left, will securely record your yacht's transmissions - no one can deny your existence. This has to encourage larger vessels to comply with SOLAS rules. The recording of AIS targets is very useful - should your tiny sailboat go missing one day, every big ship that you've passed will have a time and date stamped record of your past position to assist the search authorities. Furthermore, many shore based AIS stations (and there are thousands already in place) will see you as you pass within range and report your position - check it out here.

In my last story I mentioned that the AIS transponder provided a GPS position output in standard NMEA format. It is tempting to think of this as a useful backup to our primary GPS receivers, but think again. It seems that the AIS GPS positions are often fine tuned with differential information broadcast by local AIS base stations (hence that "high accuracy" base station we observed in Borneo). Also, AIS GPS hardware is built to far more stringent standards (IEC61108) than conventional receivers. This means that your AIS GPS system is most likely more accurate than your existing primary GPS in many coastal situations - so you should use the AIS position data as a first preference !

On Crystal Blues our AIS data is received and displayed by our PC based chart plotting software - Transas Navigator Pro. The software displays our vessel, plus all the AIS & MARPA radar targets, as live moving indicators overlaid onto the electronic chart. This is an incredibly powerful tool, derived from commercial shipping software.

AIS is in its infancy, but it clearly has a future on your boat. Thousands of aids to navigation already carry AIS transponders, so that you can see them even when the weather is thick. Some are suggesting that "virtual aids" will soon appear on your AIS display - electronic marker buoys that can be placed rapidly if a new wreck or other danger appears. These can be activated almost instantly by maritime authorities, well before a real buoy can be positioned. And in a distress situation, any commercial vessel can accurately locate Crystal Blues with ease, once within range.

This week I received an email from Jeff Robbins, developer of the highly rated Vesper Marine Watchmate AIS display. The Watchmate is a very simple (low power) LCD screen that interprets data from any AIS unit and displays it essentially the way you need it. To quote Jeff "Watchmate prioritises targets ... the most important collision risks appear first. It also filters the data to eliminate false alarms when operating in harbour or crowded situations. And it has a user selectable "profile", that allows the user to select with a single button their sailing situation (eg. anchored, harbour,coastal,offshore)..."

Phew - Jeff has done his homework, and his display screen seems probably the best way to handle AIS information if you don't already have a compatible chart plotting system, and a very smart way to go even if you do. Of course it works with transponders or simple receivers.

Whilst we don't have Jeff's screen we're pleased with the extra safety and navigational information we receive from our AIS sytem, and even more pleased that the big boats out there know exactly where we are, day and night - rain, hail or shine. AIS transponders are a great advance in safety for both coastal and ocean sailors. Cruising author and boat designer Steve Dashew says of AIS "I would put an AIS B way ahead of most other "necessities" for a cruising yacht, especially when cruising in areas with lots of rain".