Andy Howard wrote:

>> As for sails, maybe the rigid aerofoil type sails that are fitted to some
>> big freighters and tankers might be a good idea, they're more steerable and
>> more weather resistant than fabric types.
>

Now here may be the best propulsion method of all. Sail the PIC
into a local harbor. Lower the sail, and stick the bottle to a
freighter's hull using a little solar powered electromagnet.
Course, you would need a little web device inside the bottle
to check sailing schedules.

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