When I got into sailing, the energy collected by the sails drove the hull into the water and the shape of that hull determined how quickly it came out of the water and in what direction.
Push a cork into the water with a finger tip and let go. It will pop up, wherever. Now shape that cork and it will come out of the water similarly each time. Keep refining your cork hull and you continue to improve performance.
Now they want me to believe that you actually get a difference in wind speed on a piece of cloth a fraction of an inch thick. Never mind that airplane wings are feet thick and that the lower curve is not in any way similar to the upper one as they are in a sail.
And the "slots" are the magic potion of sailing?
Let's get a grip here folks; clipper ships have sailed themselves under, never to be seen again. Without Mylar sails? Yep. Reed sails got men across oceans on balsa rafts. Hemp was used to make fine sails, not smoked.
I knew "sail makers" who leathered the chafe points, did extra stitching where needed (included in cost because it had their name on it and that was the "right" way to make a sail) and produced cruising sails that held their shape through years of reefing, running and beating through gales.
Now, with computer design and mass manufacturing, I doubt that there are quality cruising sails available at any cost, let alone for a cruiser's budget.
Like so many boat builders of today, the sail makers are no longer in the business to create something fantastic, they just want to make as much money for as little effort as possible.
My mainsail is falling apart after maybe (liberally) 200 sails and when I contacted the sailmaker for ideas on how to stop the deterioration, I was told it was time to give it a "decent burial". 200 sails max! Stored and folded in a climate controlled sail loft each winter, stowed in a hood stow-away mast when aboard in the summers! It is a beautiful sail, maybe the nicest setting sail I've ever seen, but what good is that if it is falling apart? A sad state of affairs.
So y'all just keep thinking of sails as aero-foils and I'll get by on my old, outdated misconceptions, somehow getting my 53' heavy displacement ketch up to 10.3 knots, hard to weather in 25 to 30 knots of wind with only a VERY deeply reefed main and the Yankee jib in 8 to 14 foot seas? It's a mystery.
