The Upwind 360 step by step: oversheet, push the rig into the wind, control the backwind and close the circle to windward – light-wind freestyle.
What is an Upwind 360? A full 360-degree circle sailed to windward through the wind: board and sail rotate once around their own axis and you continue in the starting direction. The sail is not switched but pushed against the wind, that is backwind [2].
The honest answer on difficulty: the direction is easy, the feeling unfamiliar. Dailydose calls the move a light-wind freestyle entry and rates it level 3 of 6 [2]. Royn Bartholdi, freestyle coach, still describes it: the body feels strange at first because you stand far over the nose [1]. And backwind is the hurdle: if you push against it, the sail knocks you back [3].
If you can do the heli tack securely, you only lack the second third of the circle.
Where the skill sits in your learning chain: the Upwind 360 is the double heli tack movement: you do not just turn through the wind, you do the whole circle. It is therefore an excellent test of your backwind feel and builds on the heli tack, Sail 360 and clew-first sailing. If you master it, you have the basics for almost all moves in which the sail is held against the wind.
It is also a move that proves itself in light wind: when there is little wind you can take your time to sail each phase of the circle consciously. And you learn how much force there is in a backwinded sail without it throwing you off balance immediately.
Split the circle into three quarter phases: heading up and oversheeting, steering the backwind, turning through and bringing it up. First practise the first two phases without closing the circle. When the sail is open and the board is in the wind, you stop and sail back. That builds trust in the backwinded sail without landing in the water immediately. Only then do you close the circle. Sail it on your strong side first, then switch.
Sail slightly off the wind (soft beam reach) to gain speed [1]. Check upwind: you travel farther upwind than you think and nobody should hit you as a gybing sailor [1].
Milestone: you sail a beam reach calmly for 20 seconds, ready to start the circle.
Oversheet the sail, i.e. push the rig towards the tail so the gap between tail and clew becomes smaller, and keep pulling with the clew hand. Keep the front arm extended across your chest, eyes forward into the wind. The board heads up [1].
The board slows down and stalls. Now push the rig forward, the mast towards the wind, by lifting with the clew hand and extending the front arm ("bow and arrow"). The nose points into the wind [1].
Keep your body over the centreline, extend the front arm and lean forward in a controlled way. This feels unnatural at first [1]. The nose swings to the new side because the sail pressure sits in front of the mast foot [1]. Now the clew hand controls the power: push away or pull to your body (more collapsing, because you are backwinded) [1]. As in all backwind phases: do not push against it, keep the sail open and guide it towards the tail [3].
Aha line: the tail is your pivot, visualise it as the pivot point [1].
While the board keeps swinging you slowly shift your weight back so you keep balance with the changing forces. Then you push the clew through the wind, pull a little with the front arm so the mast becomes upright, and the sail builds pressure again with your back to the wind [1]. Trim, sail away.
Milestone: one clean circle, then two in a row, each on both sides.
Try the move as a mini version drifting on a longboard: there it shows whether you really keep the sail open in backwind. Royn names backwind sailing as the foundation of this move [1]; the more securely you master it, the less you fight in the circle.
A 360-degree circle to windward: board and sail rotate, the sail is not switched but pushed against the wind [2].
Dailydose rates it level 3 of 6 and calls it a good light-wind move to learn basic freestyle technique [2].
Backwind sailing and the heli tack. Both train the feel for the sail against the wind [1].
A bigger board until you understand the mechanics [1].
The Duck Tack in Windsurfing: Tacking by Ducking the Sail