This morning I spoke with a mate from Australia ( I love thse Aussies) and during the phone conversation he ask me how I knew when the boat was right when sailing upwind. Without thinking I said I can "feel " it. He asked me to be more specific and I really had to think about it before I could answer him. I told him I can "feel" it in my hands and feet. What I look for is that both the main and jib are balanced with a little bit of weather helm and I can feel that balance in my hands and if I let the wheel go it would want to start a slow tack. Getting the sails balanced while sailing upwind depends on the wind and sea condition, both of which dictate how much power you have to generate from your sails. After doing it a while and concentrating on your senses you can "feel" if you boat is overpowered, underpowered or just right. If it does not "feel" right, you have to make a sail trim adjustment. For example, in very light to light conditions you have to use a lot of finesse and in those conditions, getting the "feel" is a little more difficult. In medium wind (5 to 12 Knots) you really have to work the boat. For you as skipper in medium conditions, the "feel" comes much quicker and you have to react quicker to the "feel" you are receiving from your feet and hands. Next time your out sailing and you have your boat set up as best as you can, take a second and think about what you are "feeling" from your feet and hands. After you know what it feels like, it becomes easier to duplicate.