I agree ... this simulation defies "sailor's intuition" and the explanation you reference doesn't help at all - it doesn't feel anything like sailing a real boa

I agree ... this simulation defies "sailor's intuition" and the explanation you reference doesn't help at all - it doesn't feel anything like sailing a real boat. I've got a small yacht and while I can easily sail into the wind with a full main sail and small jib, there's no way in your simulation to change the angle of the jib (in front of the mast) in relation to the mainsail. The physics are wrong to since the position of the keel is purposely centered behind the sails' COE (otherwise it would be easier to sail backwards than forwards). I think you need a rudder to counteract the force of the sail swinging the boat around the keel and you need to consider that a full sail (purposely) becomes "wing-shaped" as noted above. EDITS: 1) I should also note that it's possible in some small boats to sail almost directly into the wind ... I've managed about 15 degrees off the wind in a very lightly loaded Hobie Cat (without a jib). 2) Turbulence is an undesirable effect ... many sails have "tells" sewn into them that show you how the air is moving over the sail. You never want the tell to be wildly gyrating.