ON 26JUN17 , EAGLE was sailing , enroute to Prince Edward Island in the Cabot Straight , to the northeast of Cape Breton Island , Canada . Winds were light and variable and we were proceeding slowly to the west . At 0804 ( UTC ) I observed the sun rising with the upper limb approximately 1 / 3 of a finger ’ s width above the horizon . At 2400 ( UTC ), I observed the sun setting with the upper limb approximately 1 / 3 of a finger ’ s width above the horizon . Adding the times of sunrise and sunset , and dividing by 2 , yielded a time of 1602 – the “ observed ” time of LAN . As per the Nautical Almanac ( or the mnemonics above ), the equation of time yielded a predicted time for LAN of 1203 . Converting time to arc ( 1 hour of time equals 15 o of longitude and 1 minute of time equals 15 minutes of longitude ) yields an offset of 60 o 15 ’ from the Greenwich Meridian – i . e ., a longitude of 060 o – 15 ’ West . I also observed Polaris shortly after sunset . Using my hand , and multiple observations , I measured it to be approximately 4 vertical fists (@ 10 o ) + 3 finger widths (@ 2 o ) = 46 o above the horizon ( i . e ., Latitude of 46 o N ). Thus , my manually calculated position was 46 o -00’ N 060 o -15’ W at sunset . The actual position , as per GPS , was 47 o -07.1’ N 060 o -51.9’ W . My calculated Latitude was off by approximately 1 degree 7 minutes and my calculated longitude was off by approximately 37 minutes . Plotting these positions revealed that my manual determination was accurate to within approximately 74 miles - very reassuring . Note that the imprecision described above was also impacted by the fact that EAGLE was moving ( albeit not particularly fast ). In particular , from the time that I observed sunrise , to the time that I observed Polaris , EAGLE had sailed approximately 69 miles to the west ( for an average speed of approximately 4 kts ). If EAGLE had not been moving , or moving only very slowly ( similar to a life raft ), then the error in our observed position would have been a bit lower or a bit higher ( depending upon the exact speed ). Of note , I was able to achieve similar results on other days and on other passages . The bottom line is that these techniques work .