Spinnaker Area Measurement

[AmusingOutrigger]

From my search for a bigger spinnaker over the winter, I put together a little tool to calculate the area of a cherub spinnaker from the leach, luff, foot and mid width. I thought I would share this everyone, in case anyone is interested in an easy way to calculate the size of your spinnaker without all the complicated maths.

This is the link for the page hosted on my website:

http://carwynowen.com/Home/Demo

[kerrgreg]

Thanks dude will give this a good when I have a spare minute got a couple kites I can try and I think they have both been measured with the class formula so should be able to compare

[pratn0]

what formula did you use for this?

there is a specfic fomula in the class rules that we should use.

putting some of the number from the class measurment sheet into it produces sizes ranging from 0.3m2 for a old A+E kite to 2.5m2 for an big I14 kite -  smaller than what the class measurement excel calculates.

Nice easy tool though and if we get the fomular right it will be usefull for the class members.

[AmusingOutrigger]

Hi, I used the formula from the 05 rules pdfs. But not knowing what size my spinnaker is I couldn't check I had got it exactly right. I will post the code for the formula so someone with more kite measuring experience can check it.  Could I see what the excel formula is then I can get it write from that?

[AmusingOutrigger]

Having looked at the 05 and 11 rules there is some different around calculating the F + G values, the 05 rules uses difference in leach / luff and 11 uses difference in leach and foot? Which of these is correct? Turns out my formula follows the 11 rules formula. For those who don't mind badly written javascript see below:

var lMean = (+leach + +luff) / 2;
var footPower = Math.pow(foot, 2);
var llPower = Math.pow((leach - foot), 2);

var f = Math.sqrt(footPower - llPower);
var g = Math.sqrt(Math.pow(mid, 2) - Math.pow((leach - foot) / 2, 2));

var lMeanF = lMean * f;
var a = (lMeanF / 6) + ((2 * lMean * g) / 3);