Simple GPS Navigation for Cowes Week

I have used a Garmin GPS12XL for several years in the Solent and it will certainly be in my bag when I step aboard on Saturday to navigate the fifty-footer, United Airlines. The more recently-introduced Garmin 76 Marine Map looks even better and we hope to bring you a madforsailing test of this unit shortly.

What you need

In order to work effectively for racing you will need a GPS that can display:

Time to Waypoint (TTW)
Course Over Ground (COG)
Speed Over Ground (SOG)
Bearing to Waypoint (BTW)
Distance to Waypoint (DTW)
Time
Position (Latitude and Longitude)

A hand bearing compass

A steering compass

A square protractor (sometimes called a 'Douglas Protractor'). Mark a series of concentric circles on this at half-mile intervals scaled for the chart scale you are using.

Detailed charts of the racing area.

Set up your GPS

Make sure the time zone is set for the area where you are racing. Virtually every race committee in the world uses 'GPS Time' as the basis for their race signals. It always pays to check every time, but you can be reasonably sure that the Cowes Week starters will be banging their guns off just as the seconds hand on your GPS slips over to :00 seconds.

Getting the right chart datum is vital. All new Admiralty charts (including my recently-purchased Small Craft Series ‘Solent Approaches’) now use the universal global standard WGS84'. Some older British charts may use an old datum called OSGB36. Don't worry what the datum is; just make sure the GPS is set to the same datum as the charts. Read the instructions for your unit if you do not know how to do this. It is important otherwise the positions will not be accurate.

Load all the Waypoints in before the regatta.

There is no doubt about it, loading in waypoints is time-consuming and tedious. The pain can be eased by setting up all the required waypoints in the comfort of your own home before the regatta begins. In order to do this you will need to know the positions of the marks. Most sailing instructions now incorporate a list of marks that include latitude and longitude. Failing that the relevant nautical almanac for your area will have a list of the waypoints for the major navigational marks. If all else fails you will have to plot the positions from the chart.

Fortunately, all the marks and their waypoints for both Black and White groups in Cowes Week are available from the official Skandia Life Cowes Week website. The numbers designation for the Cowes Week marks are different than for the normal Solent Racing marks. You have been warned!

With nearly 100 marks and 13 digits of information to enter for each mark, loading the whole lot manually is quite a task. It can be done (and I have done it) but you need to allow three to four hours for the job.

A much better alternative is to use a connection cable between your PC and the GPS unit. Most modern Garmin units are supplied with the correct cable. Garmin sell cables for all currently compatible units with other manufacturers offering a similar service. In addition to the cable you will also need the appropriate software to run on your PC. For Garmin users, ‘Garmin Mapsource’ is the official product. Several other (cheaper) alternatives can be downloaded from the internet. (A search of ‘GPS’ on www.download.com reveals several solutions.)

Using the correct cable and appropriate software, it should be possible to set up the system and enter all the waypoints in under an hour. Using a proper keyboard is very much quicker than the tiny keys on the GPS. There is also a much-reduced risk of error in using a PC and a cable rather than entering the waypoints one at a time.

Whichever method you use it is vital to check that the information is entered correctly. Your crew will not thank you if you blithely head off in the wrong direction just ‘because the GPS says so’. The only effective way I have ever found to check the entered waypoints quickly is to sit and read them out loud while a fellow crew member (or partner) cross-checks the numbers against the printed information.

Finally, if you really cannot be bothered with it all, a number of electronic equipment distributors offer a service - usually for a hefty fee - to install all the information for you.

See page two for tips on how to use your GPS