What Phil said.
The “I-65 Route
- 1,100 miles Miami-to-the-Virgins
number one, in the Gulf Stream, is to avoid “Northers”; the cold fronts that come blasting down the Florida peninsula every so often, usually beginning in November and becoming more frequent and more powerful as the season progresses.
A bit further on, these wind shifts will become your ally, but when strong northerly winds blow against the northbound current
of the Gulf Stream, big, steep, breaking waves build rapidly, making for a rough passage
Once across the Gulf Stream, you’re hoping for a Norther. Those same cold fronts that you were avoiding just a couple of days ago, in the Gulf Stream, can now be a real asset.
The prevailing winds here are from the East and Southeast—exactly where you want to go (naturally), but as a Norther approaches, it sets up a veering wind pattern. First, the wind shifts to the South, then Southwest.
Just ahead of the front it may die in the West.
Then the leading edge of the front comes with a cold rush out of the Northwest, usually accompanied by blustery winds, clouds and rainsqualls.
Then, as the sky clears, the wind clocks around to the North and Northeast before settling back into the prevailing Easterly again.
skippers, setting sail as soon as the wind goes South, use these favorable wind directions to make a few hundred miles of “free easting” into the Atlantic.
Around 70 degrees West, start putting a bit of Southing in your course, so that you cross the 24th parallel around the 67th meridian.
Then head roughly Southeast by a point south toward a waypoint of 22 degrees North and 65 degrees West. This meridian, often called “I-65”, marks the last leg to the Virgin Islands
and the best part of the trip. From here you sail due South, soon picking up the Northeast Trades if you haven’t already.
This is why you "head east just before a “Norther” and then head south."