GPS or Global Positioning System, was developed in the 1970's by the US Department of Defense along with Ivan Getting at a cost of about 12 billon dollars. The system consist of 24 satellites that orbit the earth about 12,500 miles above and are spaced so that no less then six are in view to users worldwide at any given time. GPS units down on earth then use these satellites as reference points to calculate positions accurate to within several meters on most units and can be as accurate to less then a centimeter on some of the higher end models. A real plus for this system is that it can be used in all weather conditions. Prior to May 1, 2000; the Department of Defense was using what is called "Selective Availability". To keep it simple, the Department of Defense intentionally made the GPS system inaccurate for civilian use. On May 1, 2000 President Bill Clinton ordered "Selective Availability' discontinued, making civilian use more accurate. Today, most of the GPS units sold over the counter are as accurate as the ones being used used by the military. This has made the use of GPS the top navigation tool not only for boaters, but for anyone that needs to know how to get to where they are going.
When it comes to touring along the coast it is essential to bring along good maps, a compass and a dependable GPS unit. The Maine coast is dotted with thousands of islands and not paying attention to where you are and where you need to go can lead to confusion and wasted time. Learning how to navigate is something that is both learned and is something that comes natural to some of us. learning to use a compass, maps and GPS units will take time and practice. I personally use a Garmin 76CS marine GPS unit, which comes standard with the Americas base map and a marine points database. You can purchase separate mapping programs, like the MapSource United States Topo, which provides enough off shore information for the average kayaker to get around on. Many models of the Garmin GPS units also support Blue Chart, which is a more detailed nautical mapping program. The use of a GPS is invaluable when it comes to planning both day trips and long tours.
Most units that are available today come with a pre-loaded regional or world base maps and their level detail will vary with each model. Many units can be connected to a home PC, which will allow for more detailed maps to be downloaded into them. Garmin now offers a model that will receive XM Weather Satellite. Model 376C measures 5.7" w x 3.2" h x 1.9" d., and was designed to be mounted, however it can be used as a hand held, You may find the price to be a little bit too much though, it retails for around $1000 and the subscription to the XM Weather service will cost you up to $50 a month. Shop around when purchasing your first GPS. Make sure that you choose a unit that will not only meet your needs today, but one that will meet your needs down the road. If you are already serious about touring or feel that this is a sport that you will get serious about, it will pay to invest in a high end unit. Just like the features, the cost will vary with each unit. Prices range from $125 to about $650 for a top end hand held unit. Choosing a GPS unit is like choosing your kayak, don't think of it as a short term use purchase, think of it as a long term investment.
Two other essential items to bring along on your trip are maps. nautical charts and a good compass. Don't rely on your GPS alone IF you plan on purchasing a GPS take a look at the optional mapping software that is available; most will allow you print maps directly from the program. There are four options available for keeping those maps dry. First there is a sealant that is applied directly to the map surface. This available from most of the specialty sporting goods stores. The second option is a special, waterproof paper, designed for printing maps on. The third option is a waterproof, plastic case; similar to a dry bag. The last option, which is what I use, are laminate sheets. These are available at most office supply stores. A good resource for up to date nautical maps can be found on NOAA's (National Oceanic & Atmospheric Administration) website. As for compasses, Suunto offers one that attaches across the deck of your kayak using 17" elastic shock cord. It can be purchased at most boating and sporting goods stores and retails for about $40. There are also several other compass manufacturers that similar units in about the same price range.