The dream of sailing around the world has inspired countless generations of people. Some are older and already established in the world, and then there are others who, like Dwight Long, take their youthful enthusiasm and make a go of it.
Long was coming of age in the early 1930’s during the Great Depression. His family was middle class but from an early age Long developed the work ethic and began buying and fixing up small boats at age seven. He would buy old rowboats and other small craft, apply a coat a paint and maybe some varnish and turn around and resell the boat only to buy another. By the time he was 20 he had done this 14 times and was getting pretty good at understanding just what was good and bad in a boat. It was about this time that he read an article by the great French circumnavigator, Alain Gerbault and got into his head that he would like to sail around the world. His parents wanted him to go to college, so Long enrolled — all the while working in his own landscaping business so that he could save enough money for his boat. Business was bad everywhere in the U.S. and Long saw doctors and lawyers working as day laborers so he figured he’d be better off leaving college for a time and buying a boat. He traipsed up and down the West Coast for six months before he found what he was looking for.
Idle Hour, 11 years old at the time, was a gaff-rigged ketch. A little more than 30 feet long, the boat was heavily built with full-length 2-inch thick fir planking over oak ribs. By the time Long found the boat, Idle Hour had already spent a few harrowing years in the far north. Long paid the enormous sum of $1,600 to buy her.
He spent the first couple of years learning how to sail the boat close to home by chartering and learning celestial navigation. And by the fall of 1934 he was ready to begin his adventure. He was 21 years old.
He departed California with a paying passenger bound for Hawaii and a little more then two years later he was in Cowes writng a book called Seven Seas on a Shoestring. He finally got back to Seattle before the outbreak of WWII, with the honor of being the youngest person on the smallest yacht to have accomplished a circumnavigation.
Mastering his celestial skills all along the way, Long never had enough money so he couldn’t afford a chronometer. He navigated using a pocket watch, whose accuracy was highly dubious. How he ever managed to get his longitude accurately is a mystery.
Let’s join Idle Hour in the Pacific Ocean. It is October 12 and he is on his way from Hawaii to Tahiti. His DR is 15° 35’ S by 153° 20’ W. He is preparing to do a noon sight and for the sake of this problem we are using the 2008 Nautical Almanac. The height of eye is 10 feet and there is no sextant error. For this sight we are taking an upper limb of the sun. The Hs of the sun at the time of the sight is 82° 43.0’.
A. What is the time of LAN in GMT at the DR?
B. What is the Ho?
C. What is the latitude?
Extended solution by David Berson
Idle Hour is at DR 15° 35’ S by 153° 20’ W. The height of eye is 10 feet. We are solving an upper limb shot of the sun. The day in question is October 12, 2008. The Hs is 82° 43.0’. We are looking for the time of LAN in GMT, the Ho, and the resulting latitude.
Meridian Passage: 11hrs 46min.
153° west long: 10 hrs 12 min
20’ west long: 1min 20 sec
Time of LAN 21hrs 59min GMT
Hs 82° 43.0’
Ha 82° 39.9’
Alt. corr -16.3’
Ho 82° 23.6’
Declination at time of sight S7° 47.0’
d corr +0.9’
Dec. S 7° 47.9’
Latitude= 90°-Ho=ZD +/- Dec.
7° 36.4’ ZD
15° 24.3’ South latitude
Note: An incorrect entry in the printed problem included an incorrect declination of S 7° 48.8’. Please disregard. Thank you.