Category: Kitesurf Academy

So if you are anything like me, trimming the kite can sometimes be more than a little bit confusing, should you pull this or pull that, connect here or connect there? Conditions are different every day so just because you trimmed your kite one way today doesn’t mean you’ll have the same setup tomorrow.

Fear not…we’ve sweated this one out over the years and this article is the sum of our mistakes and insights, simplified to a level that actually makes sense (hopefully…if not let us know in the comments and we’ll clarify!).

The aim here is to give you the basic knowledge to start trimming your own kite effectively.

Not to delve deep into aerodynamic theory.

For that reason and for any aerospace engineers out there, we are at times over simplifying reality slightly…this is done intentionally to avoid having to go into too much complex theory and enable us to get across the basic concepts in a format that you guys can actually use and apply. So if, after reading this and doing some deeper research, you find that we have bended the truth a little, please understand that it is the concepts we are trying to get across, not Einsteins theorems.

Why Trim Your Kite?

The most basic reason we trim our kite is to change the power in the kite. To ensure that it is safe and flying efficiently for the weather conditions of that day. Our aim is to be able to handle the kite safely by trimming it to a level of power we can handle, thus ensuring the kite flies properly and doesn’t fall out of the sky at the first lull in the wind, or rip us off down the beach the second we put it up.

Obviously every kite handles differently and there are many different types and makes of kites that all require their own trimming techniques. But the science behind them all is the same.

Trimming Using The Trim Strap

The first method we will look at is trimming the kite using your trim strap. Trim straps can be located above or below the bar but all function in the same way. The trim strap can be adjusted to give more or less power and works by changing the length of your front (centre) lines.

By pulling the trim strap you are changing the angle of the kite relative to the wind. This is called the angle of attack (AOA).

Imagine the position of the kite above your head when it is at 12 o’clock. If you shorten the front lines you are effectively pulling the leading edge down towards you, lifting the trailing edge. This will (in optimal conditions) change the angle of attack of the kite meaning that the air flow over it is less efficient (more turbulent), thus decreasing the power.

So to power up the kite again, it is the opposite. We lengthen the trim tab which lifts the leading edge up away from us, lowering the trailing edge and ensuring that the kite is splitting the oncoming wind like a knife, giving us smooth (laminar) air flow over both exterior surfaces of the kite. Increasing the lift generated by the kite.

Image Courtesy of KiteboardingEvolution.com

I find the easiest way to think of this is in terms of the outside/back lines as we all know what effect they have on the kite. When you pull the bar in you know that you are powering the kite up (as long as you don’t over sheet in which case it stalls…more on that later) In terms of what you are doing with the lines, you are effectively shortening the outside lines, as they get shorter in comparison to the fixed centre lines.

So as we shorten the outside/back lines, at the same time we effectively lengthen the centre lines (in comparison with the back lines) which is the same effect as letting the trim strap out, which as we know, powers the kite up.

This is a real long winded way of explaining this but I find it the easiest way to consistently get a good understanding of trimming, but please, take a moment to visualize this and check you’ve got it.

Conversely as we let the bar out, we are lengthening the outside lines, which implies we are shortening the centre lines (or pulling the trim strap in) which has the effect of de-powering the kite.

This is how my poor brain keeps track of whether I should be pulling the trim strap towards me or letting it out, by comparing it to an effect I am sure of…that of pulling the bar in or letting it out.

Testing The Kite For Power

When we’re teaching, something we do every time before we let a student fly a kite, is launch the kite and fly it at the 12 o’clock position. From here we pull the bar all the way in and hold it there. In doing this we’re checking to see if the kite starts to stall. If the kite immediately starts to fall out of the sky, backwards, then the back lines are too short, i.e. the kite is over-sheeted, the angle of attack is too acute and the airflow over the kite is too turbulent to allow it to generate enough lift to stay in the sky. Think of a plane trying to fly directly upwards without enough power.

The kite should sit in the sky comfortably for a good few seconds, or preferably for ever, before it starts to stall if it is trimmed correctly. Note, when pulling the bar in, the kite will (most likely) shift back a little bit in the window, as long as it holds this position and doesn’t continue to fall, all is good.

Word to the Wise

On light wind days or when highly under powered a kite will stall even if well trimmed as it is impossible to trim a kite correctly outside of its wind range.

Trimming Using The Kite Lines

If once we have used the trim tab, the kite is still not correctly trimmed then we have to look at changing the points at which the outside/back lines attach to the kite. By attaching the lines either closer or further away from the kite we can set the kite for more or less power. The shorter we make the back lines, the more powerful we are making the kite (the same as pulling the bar in). Conversely the longer the back lines the less powerful the kite will be (letting the bar out). It works along the same principle as the trim tab, lengthening the back lines changes the angle of attack, decreasing the power in the kite.

Testing The Kite For Steering

When we test fly kites on the beach, we are also testing the steering. The back lines (outside lines) control this, as these are attached to the wing tips of the kite and effectively steer the kite.

With the bar at the sweet spot (the point where you can just feel resistance from the bar when using only the weight of your hands and arms to set the kite) the kite’s steering should be reactive. If the steering is too quick or too slow then the back lines will need adjusting. The longer we make the back lines the slower the steering will be. The shorter they are made, the quicker the kite will turn (up to a point, but I’ll leave you to play around with this one).

Ready to be really confused?

This is where things get a little crazy. We would think, given what we’ve just said that the answer to light wind days is simply to shorten the back lines to give us more power and away we go.

If only things were that simple.

By shortening the back lines in light winds we also make the kite that much more susceptible to back stall, which due to the lack of power from the wind will happen that much sooner in light winds anyway. Often this occurs to the point where if we shorten them too much, we can’t even launch the kite as it’s so over sheeted. As a result sometimes on light wind days we have to de-power the kite (i.e. lengthen the back lines/shorten the front lines) more than we would think to prevent over sheeting and allow the kite to fly.

Brain Fried?

This is very much an art not a science and the best way to get your head around it is to go out and play, just spend 2 mins every time you go out, playing with the trim strap until you get a good idea of what it is doing and how it effects the kite, by doing that and applying the logic in this article, you should get this nailed quick smart.

REMEMBER, if you have trimmed your kite and have completely powered up or de-powered depending on what the conditions are and it still isn’t enough: CHANGE KITES! Trimming is not a replacement for correct kite selection.

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One thing that will define the way you learn during the online lessons and will contribute to keeping you safe and giving you more practice of the fundamentals than would otherwise be possible is your use of short lines.

We recommend, actually I would insist however I realise that trying to insist on anything over the internet is futile…but if you actually want to crack this kitesurfing lark I would implore you listen to the advise I’m about to give and continue with this course on short lines.

Normally kites fly on lines of between 20 and 25 m. This length ensures the kite generates enough power whilst retaining enough responsiveness to be useful on the water in normal winds. As you should know by now kites generate power as they move across the wind window, due to the action of apparent/induced wind. By reducing the length of the lines we reduce the potential power the kite can generate as we reduce the distance it can travel (and thus the speed it can gain). A stationary 9m kite on 25 m lines will have the same power as a stationary 9m kite on 5m lines (unless you want to be picky and talk about gradient wind…which I don’t!) however the kite on 25m lines has the potential to generate a huge amount more force as it has the potential to move through a much larger plane. Someone cleverer than me could tell you exactly how much more power such a kite would generate…suffice to say it’s LOTS!

Thus by reducing the length of the lines we reduce the potential for you coming to harm by messing something up…which you will (everyone does). This means that you can practice which whatever kite you have and by performing a simple operation can turn it from an out of control power machine into a child’s toy. Considering we don’t actually need any of that power until we are actually up and riding on the board you can save yourself a lot of frustration (and pain) this way.

Added to this is the fact that short lines tend to tangle less, simply due to the fact that there is less line to get tangled. This alone can save you hours during your initial sessions and means that your time spent at the beach is much more profitable. At Tantrum Kitesurf we noted that by putting students on short lines we would increase the number of runs they had in a 5 hour session (sharing a kite) from 6-7 runs to something nearer the mark of 25 -35. Thats a lot more time spent practicing piloting the kite rather than untangling lines (which you’ll do plenty of over the course of your kitesurfing career anyway!).

Last but definitely not least a kite on short lines is a lot easier to relaunch than a kite on longer lines, This is because the relative angles of the lines to the kite is that much greater that every movement of the kite has much more effect on the steering of the kite. For this reason the kite will be a lot more responsive, which actually leads to a sensation whereby when you do move up to longer lines you actually find it easier as you have more time to think about everything that is happening as it seems to be happening in slow motion.

I would recommend that you visit your local kite shop and ask them to cut your lines in several places. This does no damage or has any effect on the actual flying of the kite (as long as it’s done right), and actually gives you a lot more options to change the configuration of your kite when you are up and riding. I would recommend you to go for at least 7m and 15m cuts, so you’ll be able to fly your kite on 7m lines, 15m lines or full length lines. If you want to go the whole hog I would suggest 5m, 10m and 15m. This will give you a great range to progress through and these are the sizes we’ve had the greatest success with in our physical kitesurf school. Every case if different and your exact needs may depend on what size/type of kite you have…the Viron for example comes with the ability to shorten the lines, because of this and due to the friendly characteristics of this kite you don’t need to cut the lines any more for this kite.

However you finally do it, you’ll be helping yourself out massively by performing this one simple task. It shouldn’t cost too much and can save you time, frustration and embarrassment down the beach.

Now that some of you will be moving onto Leading Edge inflatable (LEI) kites, we’d better take some time to explain how to set these baby’s up, as it’s very different to the kites we’ve been using so far.

By now you should be happy with the concept of upwind and downwind. An object upwind is nearer to the source of the wind than an object downwind. Thus if person A is upwind of person B and person has not washed in a long time, then person B will be able to smell person A as the wind is blowing off the upwind person A onto the downwind person B.

We will be setting up our kites with the kite upwind and the lines running downwind to the bar. The reason for this will become clear when we have set the kite up.

First take out the kite. The first thing to look for is to examine the first strut you can find. The strut is one of the the inflatable condoms running the width (not length) of the kite. Have a look at how you put air into the strut. If there is a tube leading from the leading edge to the strut and no way to inflate the strut directly you have what is called a one pump system on your kite. Otherwise you’ll find a valve on the strut itself allowing you to inflate the strut directly.

One Pump

The main advantage of a one pump system is that it’s much quicker to inflate…I love them because I’m lazy. On the down side they do weight a bit more and can be a nightmare if you get a puncture.

If you have a one pump system you can simply take the kite out of the bag and roll it out with the leading edge (the large condom running the length of the kite) facing into the direction of the wind, with the struts on top facing skyward. Check all the tubes connecting the leading edge to the struts, they may well have some sort of gate system on them, if they do set these to open, if they don’t go and find out why they don’t have them from who ever you bought the kite from!

From here attach the pump leash to the leash attachment point normally found in the centre of the leading edge. Now as long as you have hold of the pump you have hold of the kite so by simply placing your feet on the cunningly crafted foot panels on the pump you can keep the kite in place with no hands!

Have a look at the valves on the leading edge of the kite. Normally you will one large valve with no type of stopper system, this is the dump valve used to get the air out quickly at the end of a session (so you can get to the pub quicker). The other valve should be smaller and may or may not have a stopper system.

You need to close the dump valve before you start to inflate the kite. Make sure the valve itself is clean and sand free (as sand will destroy valves as well!) and then fully close the valve. You do not need to push the valve into the kite (like on a lilo) but the valve should stay sticking all the way out, pushing the valve in causes damage to the bladder.

Get Pumpin’

Now simply fasten the pump nozzle into the inflate valve and start pumping. You will find that as the kite starts to form into its characteristic bowed shape the wind gets under the kite and the kite actually starts flying harmlessly in the smiley position, (you did attach the pump leash didn’t you?).

If its the first time you’ve inflated it some of the struts may not inflate properly because of kinks in the tubes running from the leading edge to the strut, straighten out the kinks and you should be gold (also check the gates are set to open before you start smashing things up).

No One Pump?

If you don’t have a one pump system, then roll the kite out like a towel, with the wind flowing over the length of the kite. You can then take a bit of sand and use it to secure the upwind wing tip of the kite only. Do not put sand all over the kite as not only is it unnecessary but can actually cause problems as the wind can now get under the kite and actually form the material into a sail shape causing the kite to take off. By securing it only at the upwind point you are ensuring the kite is simply a flag, and while it can still take off if you don’t secure it properly, once fully secured it will sit quite happily.

From there pump the struts up one by one, in no particular order and then inflate the leading edge. Half way through inflating the leading edge you’ll need to spin the kite around into the “smiley” position to prevent it from making you look like an idiot as it attempts to take off sideways.

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Securing The Kite On The Beach

You want the kite to be as hard as you can effectively manage. Be more concerned about under inflating the kite than over inflating it, most bladders are built very well these days and it’s likely you’ll break the pump before you burst the bladder! The only exception to this is if you’re going to leave it sitting on a very hot beach for a long time (which I really wouldn’t recommend you do anyway) as the air will expand and could cause your kite to explode.

Some kites come with a recommended psi (for most it’s just damn hard!) and many pumps these days have a air pressure gauge so you do this with a high (ish) level of precision. If not drum skin tension is what your aiming for (probably harder than you think!).

Simply remove the pump leash from the kite (keeping hold of the kite whilst you do) and now holding the kite by the leading edge in the centre flip the kite over and lay it on the beach leading edge down with the wind flowing over the centre strut (or panel) of the kite so forcing the kite down onto the ground.

Take some sand and place it on the centre panel(s) of the kite. The windier it is the more sand you’ll need but as my CO used to say…’there’s no such thing as overkill’ put a tonne on and it’ll save you from potential embarrassment later as you’re picking your tattered kite out of that barbed wire fence or tree that looks so far away right now!

The Bridle

Now that the kite is sorted come round the back of the kite and take a look at the bridle. The bridle consists of the lines that run off the kite in triangle formations, where the lines from the bar will attach.

These should be free of knots and any pulleys should be clear of sand and free to run up and down the line. While you are there check the lines these pulleys run over that they are not worn, as soon as these start to show signs of wear and tear they should be replaced as they are one of the major fail points of any modern kite.

Once your happy with the bridle you’re ready to…

Sort the Bar Out

Now roll the bar and lines out downwind. We do this downwind so that once everything is set up we can easily look up our lines and check everything is attached to the right bit with no tangles and in case we haven’t put enough sand on our kite we will get another chance to rescue it from the barbed wire fence as we are in the way!

Once your lines are laid out seperate them and simply match the lines up with the corresponding pigtails on the kite. Note most bars are colour coded to ensure you get things the right way round. These are often coded using the nautical system of Port or left being red…”There’s no RED port LEFT in the bottle.”

Now because at this point we are effectively setting up our kite backwards (the kite will always fly downwind of you) the rule reverses, so when setting up the kite this way we ensure that the red side of the bar is on the right hand side.

Often the pigtails on the kite will be colour coded to match the bar so ensure you are attaching red pigtail to red pigtail and all should be cool!

Something you will definitely become an expert on if you live in a place affected by tides is how the sun and moon affect the tide and how the tide actually works. This is absolutely vital to understand if you are to keep yourself safe but also get the most out of your sessions. Timing a session right as regards the movement of the tide can be the difference between an epic session and a session spent sunbathing.

What is Tidal Range?

Tidal range is defined as the difference (in meters) between the low tide mark and the high tide mark. Thus if you have a low, low tide and a high, high tide, the tidal range will be great, conversely, if you have a high, low tide and a corresponding low, high tide, the tidal range will be small.

Tidal range is controlled by the alignment of the sun and the moon. When the sun and moon come into alignment as happens twice a month then all the gravitation pull aligns in the same direction. This has the effect of sucking all the water on earth into the middle of the globe. As water cannot sit only on one side of the earth it is balanced on the other side of the world.

High, High Tides

As the earth rotates this bulge of water moves around the earth creating high, high tides as land masses encounter the ‘bulge’ and low – low tides when the bulge moves on. This alignment happens when ever there is a full or a new moon as at these times the sun and moon are aligned. It doesn’t matter if the sun and moon are on the same side of the earth or on opposite sides because the water has to be balanced on both sides of the earth the gravitation fields still align.

Low, Low Tides

Conversely when the sun and moon are out of alignment the tides will be significantly less as the water of the earths oceans will be distributed around the earth in a more even manner. This is seen most when the sun and moon are completely out of alignment or at right angles to each other, ie when we have a half moon, at this point the gravitation fields are pulling at right angles to each other so the earths water is distributed more evenly over the surface and we get correspondingly little tidal range, with high, low tides and low, high tides.

Spring & Neap Tides

These 2 events are referred to as Spring and Neap tides. Spring tides occurring at Full and New moons and causing high tidal ranges, and Neap tides occurring at Half moons and causing small tidal ranges. Because of the momentum like effect of gravity there is a slight delay of around 2 – 3 days between the moon state and the corresponding effect. Ie you will get a Spring tide roughly 2 -3 days after a Full or New moon.

Using this information you can accurately predict how high a tide is going to be on a particular day. In places with little tidal effect this may not be so important in other places (estuaries for example) this may be of huge importance and mean a difference of miles between high or low tide water marks.

The Rule Of 12ths

The rule of 12ths tells us (roughly) the amount of water that will be moving, either in our out, at any stage in the tidal cycle of a semi diurnal (twice daily) tide.

Starting at Low tide and moving towards High tide:

In the 1st hour after a low tide we experience what is called slack water. This is Where the tide isn’t really moving and thus not much water is flowing. A small amount of water will however be pushing up the beach. In this hour 1/12th of the total volume of water that is going to move as the tide comes in will move.

In the 2nd hour the flow of water will increase and speed up, during this hour 2/12ths of the total volume of water that will move with the incoming tide will move.

In the 3rd and 4th hours the tide really picks up speed and a huge volume of water will move. During each of these hours 3/12th of the total volume will move. So thats half the total volume of water in these 2 hours.

In the 5th hour the flow of water will start to slow again as the tide gets nearer to its highest mark, In this hour 2/ths of the total volume of water will flow.

In the 6th and final hour of the tide, the tide has more or less reached high tide and has entered the phase known as slack water again. In this hour only 1/12 th of the total volume will flow.

From here on the tide follows the same pattern but this time the water is flowing out.

The Time To Care

This information can again be critical in certain locations. The 3rd and 4th hour should be treated with a little respect anywhere where there is significant tide as a huge amount of water is flowing and it is flowing fast. This can have a huge effect on your safety, your ability to practice and the distance you have to walk to get back to the car.

It is beyond the scope of what I’m covering today to go into specifics of conditions that can be found at every single spot. That said you need to know if there are any particular hazards you should be looking out for, check with someone who knows about these things, kitesurfers, windsurfers, surfers, fishermen will all have a good idea of what you need to look out for.

Remember the sea is a big old girl and needs to be treated with respect.