After trying to take a nap, unsuccessfully I might add, due to thinking about this problem, I thought about an ice boat, and figured out that a sailboat that is sailing on a beam reach with the apparent wind at a right angle to the boat would actually be sailing downwind and the more efficient that a boat is, the more downwind it will be heading.
Thus to me it would now seem ridiculous to define a beam reach as 90 degrees to the apparent wind, it must be true wind. An ice boat might be able to sail on a beam reach at a speed that is close to the wind speed so it might be heading 45 degrees or more down wind. See vector diagram. So beam reach must be to true wind, which would make it extremely difficult to be precise since it is very difficult to know the true wind while sailing and the wind would be somewhat forward of the beam. I would expect that most sailors would sail with the apparent wind at 90 and call it a beam reach. I would have before this.
Now an interesting story about an ice boat, or an attempt at an ice boat. Tuttle Creek, the reservoir that I live on in Kansas and where I learned to sail, froze one year hard enough to walk on with no snow, smooth like glass, with an occasional expansion pressure crack. I've never skated on such a large surface, a couple miles wide by 40 miles long. I spent the evenings that week building a sort of ice boat, imagine a 2x4 triangular frame with a cut up bicycle fork bolted up front with a 2x4 in place of the wheel
, and a push pull stick for a rudder
. Two 2x4 runners at the back of the triangle, then sharpened steel
T iron screwed on the bottom of each of the runners and an attached lateen mast
, boom and sail rig from a 13 foot sailboat. I took this out on Saturday and I discovered a major mistake in my engineering, and knew it immediately, it would not move on inch. I had sharpened the runners to knife edges, and I knew full well that ice skates are hollow ground on the bottom to trap a layer of liquid water
melted by the extreme pressure. So I put on my ice skates grabbed the 2 booms of the latteen sail off I went, traveling at extreme speeds, probably 35 or 40 mph in the 15 knot
winds. To tack I just flip the sail over from one side of my body to the other, I was great fun, until I had the nose of the sail to far up and immediately became a hang glider, probably 5 feet off the ice. Crashing down to the ice in a surprised mass of body and sail. I decided that was too dangerous for me, the ice wasn't that thick. The next night it snowed, ruining the ice and the lake has never frozen like that again and I have never been able to attempt ice boating