Thanks for the replies. Really good stuff here.
My reason for asking is as I'm thinking about running down the ICW, I wonder how feasible it is to make day jumps on the outside -- giving more opportunity to sail than motor along. Looking at charts, there is a good number of inlets along the way -- if they are usable...
I'm doing the same thing in the opposite direction: going up the ICW and ducking outside when conditions allow. Going outside is faster than the ICW iff you can do 50 or 60 miles. Otherwise, the time needed to get out of the inlet and back in to find an anchorage can really eat up you time.
I can only sail for about 24 hours at a stretch, so the inlets not only need to be passable, but close enough together so I can get back in before I fall asleep!
My small boat has done 100 miles in 24 hours with perfect conditions, but I use 60 miles as a safer limit. I prefer to head out late in the afternoon, sail all night so I can stay awake, and then sail into the inlet during daylight the next day. I've scared myself twice trying to run dodgy inlets at night. Never again!
I'm also very careful to check the wind forecast before heading off shore. I am looking for fair winds in a reasonable range... say 10 - 20 knots. If there's no wind, it's much faster to motor in the ICW. If there's a storm coming, I'd rather not be in it.
Again, if the wind is against me, I find it's faster to motor in the ICW than to beat into the wind all day. This can be a problem when the wind turns against you for 2 weeks at a time, as it does sometimes.
Whenever I stop for fuel or ice, I always ask the dock master about conditions ahead. They hear lots of stories and are usually familiar with conditions 20 miles or so in either direction.
If I want to run a questionable inlet, I position myself near the inlet and wait for a big sailboat to head out. Then I follow in her wake! It hasn't happened yet, but I'm ready to turn around if the big boat runs aground.