As a reward for spending the winter repairing my hull, I bought myself a GPS, and am now frolicking in data.
I may even learn to sail.
Discovery 1: With a double-reefed main and full jib, sailing alone, I can point at about 60 degrees to the wind. Closer than that and the boat slowed way down. Lots of foam and dramatic heeling, but little speed. (Wind gauge battery was dead, but from forecast and water surface, It was probably about 14kt).
Discovery 2: Hull speed is not that big a deal. The boat usually sails at hull speed, given some wind the proper sail set up. (Theoretical hull speed estimated at 1.34kt x 4 = 5.34, with 4 being the square root of the approximate waterline length of 16'). Again, I was sailing with a drastically reduced rig in whitecapped but nonextreme conditions, and reached 5.4 kt. easily.
Discovery 3: Going faster than hull speed IS a big deal when you are beating into the wind. Fiddle all you want with sail trim, centerboard, and weight distribution. Sail right into a line squall so the wind is crying in the wires. You can't -- well, I couldn't--get above 5.6kt.
Discovery 4: Off the wind with the board up, theoretical hull speed is almost irrelevant. I could make my 5.4kt under jib alone, and reached 7.5kt with my double-reefed main. There is a thread on this forum about whether the DS can plane. My data says that off the wind, it almost always planes, at least if you define planing as getting high enough on the bow wave to exceed theoretical displacement speed. That happens long before the boat actually feels fast.
So what? Racers probably know all this by heart, but for a cruiser, it means you should plan on nothing faster than 5.34 kt into the wind, regardless of sails or conditions. And consider that if aren't pointing higher than 60-degrees, your distance over the water is 2x the distance to your destination. So yes, setting out for that campsite three miles upwind a half hour before dark will put you off shore a half hour after dark. This explains so much . . . .