Axel Boldt wrote:
Thanks a lot for the illuminating answers. I read somewhere that the
"sail-as-airfoil" trick is a rather recent one, and that formerly
people would just let the wind push them around. Is that true, and if
yes, how recent is the invention?

Thanks,
Axel

umm... it's probably a "AD" date rather than a "BC" but there are
designs of sails which are pretty ancient that do run as proper
airfoils, not just a drag device. The Arab Lateen rigs are I think
pretty old, as an example.

Remember what Cook found in the south seas? The native canoes "went
about three miles to our two" - European rigs were not the hottest thing
at the time.

Andy.