A sailor wishes to maintain a course round a great circle of the Earth, not straying from that circle and stopping as soon as he reaches dry land again. Which start and end points would allow the longest such journey?

Arpeggionist

Start at Japan, head down past Australia, across the Indian ocean to Madagascar, round the Cape of Good Hope, on to Argentina and the Magellan Straits, once past that it's clear sailing back to Japan. The trip will be about 25,000 miles. Jan 24 06, 1:04 AM

SOTHC

Start anywhere just north of Latitude 60 degrees South and go due east or west will mean he will go on for ever without hitting dry land. He may bump into the occasional iceberg though Jan 24 06, 1:36 AM

gmackematix

Now where did I put my globe? I can tell you instantly that SM's answer is wrong as it doesn't follow a great circle but is interesting anyeway. Jan 24 06, 12:49 PM

gmackematix

I worry that Arpy is trying to run the poor sailor aground somewhere in either the Philippine or Indonesian islands. I think if you head the other way from Japan and find a circle that misses all those Pacific archipelagoes and still gets you through Drake's passage you can get as far as Africa, after going about 2/3 of the way around the circumference. Incidentally, SM had better be careful as those latitudes are covered in pack ice for at least half the year. Then there are the Falkland Islands, South Georgia, the Sandwich Islands, the South Orkneys and, strangely, the Elephant Islands to negotiate... Jan 24 06, 1:17 PM

Arpeggionist

I just took Magellan's route (and started at the other end). If you don't make Magellan's mistake of stopping in Southeast Asia you don't really have much of a problem with the locals there. Jan 24 06, 11:44 PM