We've towed 4 sailboats from 30 to 50'. One of them for more than 100 miles. Also towed a 26' power boat (under sail) for about 30 miles. The weather was never more than 15 knots with seas no more than 4 feet but a 200 foot line worked very well. Only problem we had was chafe at our stern and had to pull in 10 feet and recleat. Steve on Brendon made a beautiful line splice to repair it that I always admired.

A really long line works fine in most conditions.