Racing home with Sir FrancisJul 26, 2007
On November, 24 sailors from six countries began the fourth running of the Vendee Globe Race - a non-stop, singlehanded slog around the world. The first to finish is expected back after more than three months; the existing record is 105 days. This race evolved from an event that took place in 1966, when a singlehanded sailor raced against the clock, circumnavigating with only one stop.
Sir Francis Chichester was the first to race around the world alone with only one port of call. Before him circumnavigators had stopped in various places en route, but Chichester was very competitive. He had won the first singlehanded transatlantic race in 1960, and he wanted to beat the old clipper ship records for sailing around the world - an awful lot to ask for a 64-year-old man on a 54-foot boat - yet he succeeded and for years held the record for the fastest passage from east to west, rounding all the major capes in a monohull. He was at sea a total of 226 days and averaged 5.71 knots.
Chichester departed England on August 27, 1966, and arrived back on May 28 of the following year. The non-stop passage that Gipsy Moth IV made between Plymouth and Sydney, a total of 15,500 miles, was the longest non-stop passage made by a sailing yacht. Chichester was out at sea for 107 days averaging 6.03 knots. Chichester ushered in the era of around-the-world racing because he was the first to be commercially sponsored, carrying the "wool mark" on his bows. This commercial sponsorship set a precedent for the financing of future races. Upon completion of his voyage Chichester was knighted, and Gipsy Moth IV was permanently bedded in concrete alongside Cutty Sark in Greenwich.
Let us join Chichester after he rounded Cape Horn and on his homeward passage. It is March 23, and Chichester is plotting his passage through the South Atlantic. "The weather," he wrote, "cleared up during the morning and I had all plain sail set again, for the first time, for ages. The wind had become a gentle breeze of about 14 knots, the sun shone, the sea was blue, and the barometer began to rise ... that day ended with a lovely starry night, a nearly full moon and not a cloud in the sky."
For this month's problem we have Sir Francis using Vol. 1 of H.O. 249 to shoot his stars. To use this volume one needs to calculate time of twilight and then to convert that into the local hour angle of Aires. The entering arguments are LHA Aires and latitude to the nearest number of whole degrees. For this example of a three-star fix we will be using the 2000 edition of the Nautical Almanac and the 2000 Epoch of Vol. 1. Chichester calculated that his height of eye was 10 feet and that the sextant had an index error of 2 minutes on the arc.
At the time of his evening star sights Chichester had a DR position of 53 - 02' S by 60- 18' W.
A. In order to calculate for evening star sights does Chichester calculate for civil or nautical twilight?
B. According to the DR longitude, what is the time of GMT for his twilight calculations?
C. What are the 7 selected stars visible?
D. What three stars will give the best fix?
E. At 22:38:15 Chichester shot Suhail: Hs was 64- 53.8'. What was his LHA Aires? What was his intercept?
F. At 22:40:10, he shot Peacock: Hs was 21- 35.6'. What was LHA Aires and what was the intercept?
G. At 22:42:15 Chichester shot Rigel: Hs was 41- 35.6'. What was LHA Aires and what was the intercept?
H. What is the fix position from the three stars?