Melbourne University Mathematics and Statistics Society

Solution for 2.5 Ship's Time (Answer = USS HOUSATONIC)

This puzzle consists of a series of clock faces, each with a pair of decimal numbers underneath. Some of the clocks are marked with the letter "S" but most have underscores. The first thing you might notice is that analogue clocks have been chosen which means that we don't know if the time is AM or PM and suggests that the position of the hands might be important.

The first hint "Me old pirate friend has left his logbook behind. I wonder where the salty dog could have been?" suggests that the clocks need to be connected to places, which can be done through the pairs of numbers that are in fact GPS coordinates. The second hint "That's a mighty strange list of places! Changing time zones like that must mess with your head. I wonder if the ones with S actually show the letter S in old London town?" tells us why the places are important as they let us associate a time zone with each clock. The reference to London tells us that the times should be converted to GMT time (ignoring daylight savings for the two relevant locations St John's and Tehran). If we do this we should see that those marked with "S" now all show approximately the same time.

The last step is to work out how the time is linked to the letter. We started with analogue times so perhaps that is important. By drawing the GMT times as clock faces the hands can be used as the flags in flag semaphore, allowing each time to give a letter. This process was described in the final hint "Convert each local time (using the coordinates given) to GMT, ignoring daylight savings time. Read the resulting clock hands using flag semaphore." and the results given in the following table:

CoordinatesLocal TimeLocationTime ZoneDiffGMT TimeSemaphore
(-23.69, 133.88)3:44Alice SpringsACST (GMT+9:30)9.56:14F
(-25.27, -57.58)6:34AsuncionPYT (GMT-4)-410:34I
(-6.16, 35.75)12:14DodomaEAT (GMT+3)39:14R
(-27.15, -109.43)4:21Hanga RoaEASST (GMT-5)-59:21S
(70.49, -21.96)10:00IttoqqortoormiitEGST (GMT-1)-111:00T
(27.71, 85.32)3:07KathmanduNPT (GMT+5:45)5.759:22S
(-29.36, 27.51)12:08MaseruSAST (GMT+2)210:08U
(33.44, -112.07)12:21PhoenixMST (GMT-7)-77:21N
(-20.16, 57.5)11:00Port LouisMUT (GMT+4)47:00K
(37.39, -5.98)10:28SevilleCEST (GMT+1)19:28B
(47.55, -52.71)6:46St John'sNDT (GMT-3:30)-3.510:16Y
(35.69, 51.38)12:51TehranIRDT (GMT+3:30)3.59:21S
(43.17, 132)8:06VladivostokVLAT (GMT+10)1010:06U
(-43.95, -176.56)10:12Waitangi BayCHAST(GMT+12:45)12.759:27B

Reading the letters in order gives the clue "FIRST SUNK BY SUB" with the answer being the USS HOUSATONIC, the first ship ever sunk by a submarine, the Confederate H.L. Hunley during the American civil war.