Re: U.S.-Bahamas, Crossing the Stream
To the original question -
You have a couple issues here which I don't think have been adequately addressed yet. First, from Cape Hatteras in NC to Palm Beach in FL, the coast falls away to the west. That means that any Bahamas bound trip leaving south of Beaufort NC (but north of Palm Beach), will have to cover additional miles to the east.
Charleston might be the best example of a bad departure point. Yes, you are further south than Beaufort, but you are much further west. In addition, at WPB and at Beaufort, the GS is rather compact and close to shore. Compact means that you can get across it (and out of the associated dangers) quicker. Closer to shore means that when you set out you will have a better understanding of what the conditions in the GS will be when you get there. At Charleston the GS is far offshore and not at all compact (narrow). That means you are covering additional ground with a less foreseeable weather for the most volatile part of the trip and the duration of the time in the stream may be significantly longer. Those are some of the major offshore to the Bahamas points for consideration.
As you get further south and are considering an overnight jump to the Bahamas from Florida, the issues have been more clearly discussed already (the need to work against a fast moving portion of the GS). Hope that helps some. Do a search and find some of the GS charts online and you'll get an idea of where it runs (distance from shore) and how fast and how compact it is in various locations. Combine that with an understanding of the way the US east coast falls off and you'll have a better sense of the different routes and the conventional wisdom.
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