fin calculator

hi there. I'm going to prepare the on-line system(website) that would help to choose beginners the right fin, depended from sail size, board type, sailor weight and conditions. But I've got quite big problem how to connect all variables thogeter to get the right fin size. can any one give me some clue ??

ps.there is such calculator on boards website http://www.boards.co.uk/kit/finsize/index.asp but I can't figure out how it works because i'm not good java script, my script going to be made in php.

bOGO,

Why rewrite the wheel? Can't you just link to the Boards site?

They appear to use this formula:

finvalue = (vSailsize*5) + boardbias + wfactor + abfactor + confactor;

wfactor appears to be sailor weight - 4, but sailor weight is a range of kg, so it's not '90 - 4' but some predetermined setting, like '2 - 4 or 6 - 4'.

boardbias appears to be based on board type... smaller boards have smaller factors (0) bigger boards have bigger factors (1, 2, 3, 4, etc).

abfactor is 'sailor ability', subtracted from two where the better the sailor, the higher the abfactor (a 4 would subtract from 2 to get -2 so it looks like better sailors get a cm or two less fin).

confactor is similar ('conditions'. The bigger the wind, the more powered or overpowered, the less fin. Also subtracted from 2.

There is a copyright, but it's for the Javascript. Still, you should give them credit on your web site, I have found and still find their calculator to be useful.
http://www.boards.co.uk/kit/finsize/mainpage.asp

I don't see the need for a new fin calculator, though, since I used sail size * 5 as the base to get me close, or if I'm near a computer, use the Boards' Fin Calculator. Experience is taking over for me now, too, as I'm getting more familiar with what I need to use based on feel, not numbers.

You can see our chart at www.gsport.com Bill Kline Gorge Sport USA Curtis Performance Fins, Orca Fins, Orca Kite Fins Hood River, OR USA

ph/541 387 2649 fax/541 386 1715

Very good, grasshopper (insert sound of one hand clapping)...science stops at the water's edge...let the dance take over...

WARDOG

that is not the point - rewriting. allthought the system should choose the right fin size it's going to choose right fin from the offer of one fin designing company. so there is no way to put the link to some other site.

believe me if I'll use their algorithm I'll put some link or something..

ps.thanx 4 all explanation of this java. I'll post the link if I'll make it.

Let me suggest one criterion: don't get too technical about it. Decimal points are unnecessary. As long as a beginner's fin is anywhere close to acceptable, it should work fine. A beginner isn't likely to push a fin as hard as an advanced sailor will, nor at the speeds nor in as much chop as an advanced sailor. So as long as it's big enough to let him push against it when trying to plane and small enough that it doesn't rail up a soon as he's planing, I'd think it would work pretty well. Maybe you could provide a range of acceptable sizes for people who just want to go sailing, and add some technical fine-tuning advice for the beginners who need or prefer to wallow in details. Just tell readers with a smiley face that the technical section is not critical until they start racing, that it's for those who actually WANT that stuff, so the zen types can just go have fun.

Mike m/

I agree.

What surprises me is that the fin's area is often forgoten!!!

That's astounding, considering it may be THE most significant number in how much fin is required to offset all the other parameters. Isn't specifying only length akin to saying the best motor vehicle for a 6-foot black bilingual woman school teacher is a Buick ... without knowing whether her objective is hauling cattle or winning a top fueler drag race? Mike m/

Surprise, surprise... How about foil and flex? They are even more forgotten... Fins are fairly simple, 3-dimensional objects, that operate in a multiphase environment...I love looking at marine mammalian fins... such refinement.

WARDOG

But I believe area of fin compariason to be completely irrelevent until one person is willing to take the job of placing every fin on the market on a grid and then counting one cm by one cm squares.

Unless the method is the same for all fins made by all... all conclusions are suspect and thereby the results are statistically irrelevent.

Do anything less and submit it as a seventh grade science project, your teacher will flunk you. Bill Kline Gorge Sport USA Curtis Performance Fins, Orca Fins, Orca Kite Fins Hood River, OR USA

ph/541 387 2649 fax/541 386 1715

Flex seems to be the last defining characteristic when selecting fins. It takes a lot of testing and know-how to get it right, but that seems the way things now go at the 70cm limit in formula. Getting flex right is all about feel, but when it feels right it feels REALLY GOOD.