It’s a completely different story if you are riding with a foil board. With the foil, it’s more about the fact you need the initial hook of power to get you up and onto the foil. Once you are on the foil, the size of the kite doesn’t matter anymore as you are able to generate so much apparent wind. With foiling in the lightest conditions, the size of your board will make a difference in the kite size needed. The more volume the easier it will be to get up and onto the foil. Once you’re up and going, the 13 for example will generate the same amount of apparent wind as the 15, so it’s all down to how much initial pull you need to get you up and going. If you are used to riding smaller kites and you think you have the skill level then you could size down to a 13, if you are a larger rider and need the extra power, take the 17.