705 riders can do it
It is when a board reaches sufficient speed to travel on the minimal of wetted area or surface of water.
How do it
Planing is one of the windsurfing basics, which grants a remarkable feeling of lightness and flight. In order to begin planning, you need to know how to ride in a harness and control medium and large sails.
To start planning, you need to hang back on the harness and close the sail. To do this, begin to accelerate — shift from the center of the drag over the side of the board, pushing the board under the sail with your legs — and close the sail.
Step back away from the mast joint, so that your front foot is at broadside near the front strap, and your back foot is at shoulder width, between the front and rear straps.
Push the board downwind into the sail. Keep your body weight over your front foot and do not sit down on your back leg. Always look downwind and not where the board is headed. Try not to bear off.
You need to be entirely hanging on the harness, with your front foot under your front knee, with your hip, shoulder and head right over it. Do not in any circumstance lean back to the stern. Hand outside the board, keeping your feet on the board and pushing it out from under you.
Lean away from the harness and close the sail. Your board should get to maximum speed and begin planning. If you're going upwind hard, bring the sail back a bit, bring your body weight forward, push down with your back leg and look upwind. If you begin to bear up, i.e. turn upwind, then that means your overloading the stern — bring more weight onto your front foot and push the sail foward.