^ Fascinating, yes.. they are almost flying, only tied to the water by fins and to have a resistance for cutting across. You have to stem your boat against the wind pressure, to be able to sail against the wind. Those new catamarans are indeed skimmers or surfers, not classic displacement boats like with the America's cup started initially.
Personally i do not like those catamarans, built for one race and then wrecked, all carbon fibre and as thin as possible, barely being able to survive one race. A lot of those crash, because they are built to the limit of what the material can take before breaking, and carbon also suffers from material fatigue after having taken a certain amount of beating.
I prefer displacement boats, slower but also (even much more) graceful.
The crew changes position to adjust weight and keep the "boat" from capsizing, also the more upright the hull is the faster it is in the water, theoretically (based on purpose and design of course).
Winches are used for trimming all kind of ropes to give the sail the best form for the existing wind, to be as fast as possible. It also depends on the course; while a sailing boat can of course run with the wind and at half wind, it can not directly sail against it, only crosswise.
Then the mast can be adjusted bending it forward or back via the main stays, the sails can be reefed, lowered or set, all needing winch action at some time.
A course of say 40 degrees against the wind is already considered as very good achievement, it all depends on the hull/fin/sail form, and stiffness of the materials used.
If your course is going directly against the wind which e.g. comes at you from 000 (North), you have to sail up some meters 40 degrees e.g. left/port at a course of 320 degrees, then tack ("go through the wind") and fall over to the other right/starboard side and sail on a new course of 040 degrees for a time. So in this case you are zig-zagging around your intended course line, to reach your destination.
The course against, with or whatever with the wind is not the real (compass) course, of course. (Are we on course? Off course, we are..
)
The windex at the mast top and also at half mast height with racing boats, tell you where the apparent wind is currently coming from, and the helmsman shouts his orders to the winchcrew, to adjust the sail. He sees how fast the boat is and feels the rudder's resistance, as the hull action.
So turning the winches is done to adjust to changing wind conditions, slightly changing course or harder turns, then tack and jibe.. On a race, this of course looks hectic.