High Speed Sailing Safety
As your speeds increase, there are several things to keep in mind. Safety is first; make sure you have a sailing area of sufficient size to allow safe turning and stopping.
Sailing and turning at higher speeds require slightly different technique than slower speeds. Always be ready to sheet out to reduce speed or hiking. Make sure your lines are not wrapped around anything that would keep you from sheeting out.
When sailing at faster speeds and in higher winds, you will find it necessary to sheet in very tightly to keep the sail from luffing or flapping. The apparent wind will also feel almost like a headwind at those speeds. The goal is to flatten the sail as much as possible to reduce aerodynamic drag. Think of the difference in airfoil shapes on a slow speed plane and a high performance jet. The wing profile on the slow plane is thick, with a deep curve at the leading edge while the jet has much less curve. You have the ability to alter the shape of the sail somewhat by bending the mast through sheeting. When sheeted in tightly, the boom is pulled down and back, bending the mast and flattening the sail. Watch the luff pocket just aft of the mast for wrinkles. If there are wrinkles and you are fully sheeted in, try pulling down on the front of the boom to stretch the sail vertically. As usual, always be prepared to sheet out if necessary.
When turning into the wind (tacking)at high speeds, it is sometimes necessary to shift your body weight forward to give the front wheel additional traction. This is a result of the aerodynamic drag on the sail, which causes the front wheel to unweight. You will also need to sheet in as you pass through the turn to keep the sail from flapping as it goes from one side to the other. Be ready to sheet out as you turn back across the wind.
If you have enough room you may want to attempt a jibe, which is turning off the wind. Executed well jibing is fast, fun and exhilarating. Done badly it's dangerous and possibly painful. So with that in mind, here are the parameters for a successful jibe. A steady wind speed and direction, so that you don't get suddenly overpowered in the middle of the turn. You should be sailing at the speed of the wind or faster. You should be able to sail with the sail fully sheeted in, not overpowered with too large of sail. Sufficient room; I cannot stress this enough. Once you commit to a jibe there is no turning back.
To perform a jibe, head across the wind, sailing at or above wind speed, fully sheeted in. Turn downwind, keeping the sail sheeted tightly. The sailer will accelerate into the turn. As you go through the turn the sail will cross from one side to the other, and if you are not fully sheeted in you will be immediately overpowered when the sail crosses over, possibly flipping you. When you are in the portion of the turn headed directly downwind, there will be very little force on the sail. You are basically coasting with the wind at your back. As you come out of the jibe you will power up, accelerating out of the turn. Resist the impulse to sheet out before you are headed across the wind, since the sail will actually power up. When you are headed back across the wind, adjust the sheet as needed.
Have Fun and be safe!