Physics question

[Aramike]

Originally Posted by August

A buddy of mine claims that two ships located in sight of each other on a becalmed sea will always slowly drift towards each other until they collide.

Is this true or is he telling me a sea story?

I'll go with sea story, because physically it makes no sense. If the sea were completely calm with no forces interacting with the vessels other than flotation, than the vessels would actually move only in accordance to the rotation of the earth. Clearly seas can never be completely calm and therefore there are always forces. Instead he must be suggesting that all forces would cause vessels, independant of said forces, to intersect, but that makes no sense because they could not move independant of said forces.

Finally, he would have to be implying that all the forces involved by themselves must intersect, and they would be completely impossible in all circumstances, because should all forces intersect at all places they must be completely equal and would therefore cancel one another out.

PS: By forces I mean, currents, wind, etc.