How long would it take to sail from Baltimore MD to Jacksonville FL in a 43 foot ketch?

Insufficient data is available for a decent guess. Given a competent crew and a skilled Captain, top of the line Navigational equipment, a clean bottom, better than average sails and rigging, the correct season, good winds and weather somewhere around 40 plus hours should do it. If you are in a hurry leave your ketch at home and take your Lear and you can be there in two hours. It is a twelve hour drive in your stretch limousine so that would be a good alternative mode of travel.