I’m on a Boat

Today I’m on a boat (viewer discretion advised). It’s pretty cool, but I have been having the hardest time for the past few months figuring out how ships sail upwind. My difficulty stems from my strong understanding of the physics of wheeled things. If you take a little Brio train or matchbox car, set it on the floor, and push it at a diagonal angle backwards, it will go backwards. If you orient a sailboat so that the wind is hitting it from a similar angle, it will go forward somehow. Today I hope to receive a full hands-on education in the matter from the crew of the Mystic Whaler, but here‘s what the internet has to say:

First of all, you can’t sail straight into the wind. You sail at an angle, and tack back and forth across the wind in a zig-zag to go in the direction you want to. But how do you go upwind at all? It’s because of the sail. The third link sailing link I give above gives cool physics force diagrams and compares the phenomenon to the example of holding your hand out the window of a moving vehicle. The wind is coming straight at you from ahead, and if you hold your hand flat and almost horizontal with the front tipped up slightly, you feel the wind deflected down off the bottom of your hand and the resultant lift force pushing your hand up. With a boat, that force pushes the boat sideways and slightly upwind. The keel keeps the boat from moving sideways, so the boat goes upwind.

That’s basically how it works, but I’m still not 100% clear on it. As I said, doubtless I will be fully educated today and in the next two days, but this is my starting point.

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