[Sherman Logan]

I sailed a hundred leghe (miles)

A league is not a mile. It's 3 miles. So depending on which mile was used, 100 leagues would to 240 to 460 miles.

[SunkenCiv]

http://ro.wikipedia.org/wiki/Leghe_(unitate)

[scrabblehack]

I get 482 miles to the 73rd parallel on the east coast of Greenland. It’s not that far west.

240 miles as the shortest route to Greenland - this would be about the 68th parallel.

600 miles to the east coast at the 63rd parallel.

Greenland’s much larger than England though....maybe one of the islands of the Canadian Archipelago?

But that’s more like 1400 miles at the 73rd parallel.
1250 at the 63rd parallel.

Hmm....maybe oceans were deeper then??