GPS – A Navigation Game Changer


Back in 1965 in order for the sailor to know where they were when far from land they had to rely on a sextant, an accurate time instrument known as a marine chronometer, and tables to show the position of the sun and stars.

A sextant is like a big hand held protractor with a split screen.  To use it you had to stand up on a pitching and rolling deck then look into one end to find the horizon on one side of the split screen and at the same time, you had to find a known star or the sun in the other split screen.

sextant 1Then you had to line the two of them up and look at the “protractor” part of the sextant to read the angle between the them.  You also had to record the exact time that you did all this.  Then after all that, you had to go down below deck and look up in this big book of star and sun calculations to get the information you needed to compute your longitude and latitude.  Sometimes this took hours to complete and if you were off by one of the many variables your plot could be way off course.

Sailors have been using this method to figure their latitude and longitude since 1761. The British government offered a large prize of £20,000, equivalent to millions of pounds today, for anyone who could determine longitude accurately. The reward was claimed by a Yorkshire carpenter, John Harrison, who invented the first timepiece that didn’t need a pendulum to keep time (you can’t use a pendulum on a rocking ship).  Sextants had been around since the early 1700’s.

sputnikToday, thanks to 3 things; Sputnik, the cold war, and the Department of Defense all that has changed.

Sputnik was the first man-made satellite to circle the earth.  Launched by the Russians in 1957 it scared a proud nation into the fact that the Russians were ahead of us in the cold war.

So the Department of Defense asked our scientists to figure a way, using satellites, to pinpoint the position of our Navy subs that were lurking under the earth’s oceans carrying nuclear warheads aimed at Russian cities.  They figured that if a submarine captain knew where he was when he surfaced, and he knew the coordinates of Moscow, then the US could have a huge advantage over the Russians.

subThis was the beginning of what we now know as the Global Positioning System, or GPS.  GPS is still maintained by the US military, but is now its available for the public to use.  It consists of a series of 20 low orbit satellites circling the globe sending information about where they are and what time it is, to receivers on earth.

Whether you know it or not, all of us use GPS technology today in our cars and our phones.  When you ask Suri how to get home, it takes her just a fraction of a second to figure out where you are, where you want to go, and the best way to get there.

Out at sea we use GPS receivers plot our exact location on our electronic charts.  GPS is so common that just a few years ago mariners are no longer required to even have paper charts on their vessel to navigate with, let alone a sextant and chronometer.

golden gateOn July 11 Five of us will be racing in the Pacific Cup Yacht Race; 2,050 nautical miles from San Francisco to the finish line at Kaneohe Bay on the north shore of Oahu.  While at sea for the 13 or 14 days it will take us to get there, we’ll be relying on GPS for a number of things.

First, to show us where we are on our electronic chart and laptop and to show us where the finish line is.  But it will still be up to us to us to figure the fastest way to get there using our knowledge of the sea, weather, and sailing experience.

epirbIn case things go very wrong while we’re out at sea, GPS will also be there to help us out.  We’ll be carrying an EPIRB, an Emergency Position Indicating Radio Beacon, that will send our position to the coast guard if our ship goes down.

I’ll also be wearing a small personal GPS devise known as a MOB, short for Man Over Board.  If I accidentally get washed over the side, this devise will send an alert our boat, and the boats around me, of my position so they can come back to pick me up if they want to.

YB trackerFinally, every boat racing in this year’s Pacific Cup race will also be carrying a GPS devise called a “Yellow Brick” named for its distinct size and color.  The Yellow Brick will constantly send our location, speed and heading back to a website maintained by the race committee on shore so that they, and anyone wishing to follow our race progress, can do so from the website

Over the past 5 decades the world has seen tremendous advancements in so many aspects of our lives, the Global Positioning System is just one of them.  But regardless of technology, we will still have to rely a combination of good luck, fair winds, and our over 200 years of collective racing experience as we race across the Pacific.




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