Water start on a directional without straps: gear, kite size, spot choice and the danger from your own board. With prerequisites and milestones.
The honest answer first: the strapless water start gets you onto a surfboard with foot pressure and kite pull, on a board that is not attached to your feet. You lose the firm hold of straps, but you gain the feel of a wave rider. The IKO handbook puts it soberly: a strapless directional makes it a bit more complicated but, once mastered, gives the feeling of a surfer catching a wave [1].
Why I approach this topic carefully: without straps the board slips away more easily, and a moving board can hit you. IKO explicitly warns that waves can push a board towards you and hit you in the back [1]. And the data show that kitesurfers with loop bindings generated lower forces on landing than with fixed boot bindings [2]. Strapless is different again.
This guide explains prerequisites and build-up and does not replace a coach.
Choose the kite so you can still depower in gusts. Too much power and a floating surfboard do not go together [1]. Milestone: you explain why your kite is right for this wind.
Before the kite pulls, lie on the board, feel its volume and practise placing your feet. Without straps your foot position is the only connection (practice). Milestone: you stand stably on the board in shallow water without the kite pulling.
The kite sits low in the window and pulls evenly so you are not surprised (practice). Milestone: the kite pulls evenly and you relax your arms.
The kite produces pull in the direction of travel, the board starts gliding, you stand up (practice). If the board slips away, let it go. Milestone: you stand and glide a few metres.
With the rear edge you steer direction and height. What you learned about edge pressure helps here. Milestone: you ride one lane and hold height.
What matters is what you do when you fall: kite at the zenith, board in sight, no grabbing for the board in the waves. IKO advises keeping the board in view [1]. Milestone: you fall in control and pull the board to you without getting tangled.
The biggest risk is not the start but what follows when you fall in waves. IKO names two typical situations: the kite can front stall and fall into the water, and the board can hit you from behind [1]. In addition, if you cannot relaunch quickly, trigger the quick release so waves do not rip the kite apart or drag you under [1].
Mind right of way on waves: IKO states as a rule that the first rider on the wave has priority and a kiter on starboard tack outside the wave gives way [1]. Many riders do not know the rule, so always keep your distance. This guide does not replace supervised training.
Make your first strapless day without waves and without ambition: just a water start and one lane. When that works, the wave comes. Strapless riding rewards patience, not speed. Set yourself a single goal per session, such as five clean starts per side, and end the session when you reach it. (practical experience)
IKO generally recommends a directional but also says every board has advantages. A twin tip is more comfortable, a strapless directional more demanding [1].
That cannot be derived from the studies. Measurements show loop bindings produce lower forces on landing than fixed boot bindings [2]; I lack data on strapless.
For jumping IKO calls it taboo [3]. For waves your school decides. Note that the board leash was linked to injury rate [4].
No period is documented. It depends on water start, board and wind.
IKO advises a kite with good power and depower reserve that never overpowers you, because every wave adds apparent wind [1]. A smaller kite also reacts faster to direction changes and loops, which happen often in waves [1]. The exact size depends on weight and wind, ask your school.
Directional Jibe With Footswap: Changing Direction on the Surfboard