I grew up and learned to windsurf in El Médano. Here we have waves nearly every day and the stronger the wind, the bigger the waves. In other words, for me it came naturally to pick up speed and at some point hit the wave right to tale off into the air.
Most people who pick up confidence to windsurf at speed here end up doing a windsurfing jump sooner or later, mostly by accident. Let’s look at how to make a controlled jump so you can enjoy some air time without risking a crash.

Speed

In the same way that when we are skateboarding, skiing, cycling, etc. towards a ramp, the first requirement to take off into the air is that we hit the ramp at speed. The faster we go the higher the jump.

Course

You an pretty much jump off on any course except the running course. The run up however I recommend to be a broad reach in order to have as much speed as possible and the option to luff up a bit for a sudden increase in wind-power availability by luffing up. To start off, the best angle at which to jump off at is 90 to the wave so the your board lays flat on the water surface and doesn’t dig in on one rail when going up it. Later, as you get better, you can change the course at which you take off.
Jumping off at a closed reach will usually result in slowing down in the air and landing vertically, meaning that you will have to start sailing again from a standstill.
Jumping off at a beam reach is good to maintain speed. This course is best for long horizontal jumps to keep planing after you land.
Jumping off at a broad reach is best for tricks in the air although your option for a long horizontal jump remains. However, controlling the landing at this course might be tricky if you are unexperienced.

Sheet in at the last moment

In order to get a little boost in speed we want to sheet in in a powerful manner just as we go up the wave. The boost is necessary to compensate for the slight loss in speed due to the sharp incline of the wave face.
Body tension
When in the air we have no water resistance to limit our movement in the air. This means that in the same way that we had to adapt our way of controlling the gear when going from the beachstart (with contact to the ground) to the waterstart (only contact to the water), we have to learn how to control the gear when jumping (only contact to the air/wind). The idea is the same as for the waterstart (leaning sail forwards or backwards/ pushing on the mastfoot of pushing on the board) only that in this instance we need to keep more body tension as now the board is not limited in the vertical axis by water.
Basically what happens when we do not stiffen our body in the jump, the feet will drop, taking the board with them, our body will be stretched and we have no real control of what the gear is doing. Keep the knees tucked in close to your chest and maintain some power in the sail.

Landing

Depending on how steep the wave is at the time of take-off we will do one of two types of jumps:

Flat horizontal jump

This is the jump you will be looking for with freeride and slalom equipment as it aims to maintain the speed all the way through the jump and landing without losing the plane.
When the wave is rather flat when we hit the lip (or the wave is pretty small) we will do a long distance jump where the landing will be at speed. Here it is important that we land with the board nearly horizontal. It is especially in these kinds of jumps that it is important to keep our body tense as if we don’t do this we will have less control over the kit, our feet that drop will make the board nose turn into the sky and when we land with the aft end first and the board pointing upward we will make a sudden halt due to the water resistance. The result can very likely be a catapult.
I insist, make sure you keep your body stiff and the equipment steady in the air and you will get more comfortable with each jump.

Steep vertical jump

These are the impressive kinds of jumps. We aim to hit the wave so that we leave the top of the lip just before it breaks (or when it is at a 90º incline). Again, as we start to go up the wave we must sheet in the sail to compensate for going up the incline.
As we go up, we want to keep the body tension that I don’t get sick of mentioning. If we are able to keep a stiff body we will be able to go higher. Make sure that you keep having power in the sail as in the jump it will act like an actual wing lifting you upward. Once you have reached the top, keep the position of the gear so that you land with the fin first. Landing on the water with the board horizontal will damage the board as the sudden impact will cause the board to delaminate and go soft. This is only the case for the vertical landings, for horizontal landings the consequences are not so great.
Another alternative is the nose dive which is pretty complicated and pretty dangerous if you are not experienced in jumping. The idea is to turn your board from having the nose pointing upwards at the top of the jump, to have it pointing down by the time we reach the water to land with the bow first. If we get the angle wrong we either land with the board flat (delaminating the board over time) or diving in too vertically (and risking a catapult, potentially onto the board).

Equipment not Suited for a Windsurfing Jump

Beginners kit: although I have done so many times during my lessons because the waves in El Médano are big, I don’t advise anyone to try it, especially not if you’re only just starting. The board is so big that the wind will blow it out of control.
Formula gear: For the same reason as above, the board has so much surface that you lose control in the air. Also, the boards are usually very flat, with not scoop or rocker, meaning that the boards nose will more likely dive into the wave rather than over it. Additionally, since the boards tend to be very light (for their size) the control that we have over them in the air is even less.