I guess it depends on what shore they are sailing off of, but off the East and West coasts of Florida, there is the Gulf Stream and it is found at least several miles offshore. This moves the water faster than in shallower waters, which do move with it, but not as fast as actually in it. So I would say going up the East coast of Florida they were probably out 10 miles or more, so they could catch the current, plus it was safer and deeper. They would take this until Cape Canaveral then go offshore NE until Bermuda, then straight to Spain. Off the West coast maybe even farther out. I have seen the gulf stream with 3-4 mile an hour current. The galleons were slow, and mainly sailed with the wind(slowest point of sail), so a strong current would help them. They took currents and prevailing winds here and home.