Wether you’re new to kite surfing or a seasoned long term kiter there may still be a few things to learn.
If you just stepped into kiting without doing any prior ‘wind based’ activity you may not be familiar with the term apparent wind or you may have heard of the term but don’t fully understand it. That’s ok, we’re here to lay it out in simple terms to help you get to grips with the basics.
the wind as it is experienced on board a moving sailing vessel, as a result of the combined effects of the true wind and the boat’s speed.
So, what does it mean? OK, imagine you are in the car, you are stopped and the window is open. There is wind blowing directly onto the front of the car at 20kph. You hold your face out the window and you can feel 20kph of wind on it. Easy. Now you start driving into it, your speedo says 40kph, your head is still hanging out the window are you feeling 40kph of wind on your face? Nope, you are feeling 60kph, your car is pushing through 20kph of wind to do 40kph over the land so the airflow is 60kph. Easy eh.. Well hold on! We are sailing (kiting) we can’t go directly into the wind! so whats going on there?
OK, lets get on the water, I know for a fact that cruising about we do about 20-30kph at speed so we’ll say 20. The wind is blowing at 40kph (so about 21knots – nice and breezy) BUT we can’t go directly into that wind, so we tack at angles slightly higher into the wind than away from it hence we get up wind eventually. BUT have you ever noticed that sometimes you’ve got a good lick of speed on but for some reason you don’t seem to be able to make as much upwind ground as the guy who’s going a bit slower? What’s going on?
Right, for the example we’re doing 20kph forwards, the wind is coming from out left at 40kph. When I’m stopped I’ve got 40kph blowing from my side and i kite forward at 20kph. This affect alone of me travelling at 20kph is generating my own wind (via speed) BUT it’s not coming from my right (where the wind is coming from) its in front of me, that means the direction of the wind affecting my kite has shifted more in front of me. OK, but doesn’t that affect my kites wind window? Good question (I hope you asked that question – if you did can you see where I’m going?)
If you haven’t worked it out already, the wind effectively moves around more in front of you, this in turn has the effect of making the kite move further back in the real wind window – to the front of the apparent wind window – effectively meaning you can’t go upwind into the true wind angle as if you were stopped.
Thats great! But what does it mean??
This means that whilst it feels awesome to splat about flat chat at mach 10, IF you really want to get back up wind and you are struggling, S L O W D O W N! Edge harder with your board and keep the speed down. If there is good wind and you are powered up then you can crawl along quite slowly and get great gains up wind quickly, or you can use this to your advantage when trying to hold position in the surf by almost stopping and holding ground in a small area. You may also have noticed this when shooting down the front of a wave and you get overpowered and the kite starts to pull you backwards, this is the apparent wind shifting so far forward you are now dragging your kite into the wind and you end up heading a lot more downwind and overpowered.
So, next time your smashing about on the water give it a think and see if you can work out whats going on. This is just a simple overview into the affects of apparent wind going upwind, there is a lot to cover here with kites as they are so dynamic in the sky unlike a windsurfer or a sailing boat. We can generate our own apparent wind by flying the kite about in the sky. It’s what makes us go up and will always always be the reason why we will always come down!
Interested in knowing more? Have a google around, there are some good images, all the math and some great reading.