Monday, November 22, 2010

Updated Windsurf Calculator Online

Note: the Kiteboard Calculator can be found here.

When I realized I could embed an Excel file on my blog I decided to do it with the latest version of my Automatic Windsurfing Equipment Calculator. Heh heh heh. Some changes from the old version of the calculator are: 1) Fixed the lbs / kgs typo, 2) Added a decimal place to the wind strengths table, 3) Simplified the fin size calculator, 4) Added several more categories of board to the board size calculator. Let me know what you think.

Calculator embedded below, or download the file here.


Boris Terzic said...

Hmmm not working for me on my laptop... Will try the PC when I get the chance.

Johnny Douglass said...

Not working for me either now but it was working for me this morning. Just see blank white holes.

M said...

Thank you. It worked for me in Open Office. As a neophyte windsurfer the previous version has helped me avoid some poor choices.

Michael S.

James Douglass said...

Boris and Johnny- Well, dang. I hope it starts working. I guess I'm not surprised that the online functionality provided by Microsoft is quirky.

M- Glad to hear it opens in Open Office. :)

CdnGuy said...
This comment has been removed by the author.
CdnGuy said...

I see the spreadsheet, but get an "Excel error, your session has exceeded its limits and has been closed error." in google chrome once I enter my considerable weight.

James Douglass said...

CdnGuy- I've been getting the same message lately. Probably best to just download the file.

shawntkeating said...

James please make an updated version for kiteboarding! Or tell me how!

Colum Horgan said...

Many thanks for this
I have a quick (possibly stupid) question. I'm confused about what is and isn't considered a short board, especially as many beginner boards are short and wide now.

So for a 145l Starboard Carve should I be looking on the Shortboard curve?. FYI, I'm 75kg and planing reasonably comfortably.

Many thanks,


James Douglass said...

Hi Colum,

That's actually a good question. A shortboard is any board that lacks a daggerboard and is designed primarily for planing. Based on those criteria your Carve 145 is definitely a shortboard. Even a big formula board is considered a shortboard.


Valkyrja AEvi said...

mmm....does the fact of being a girl change anything?
I would never go out with a 7 for a sail, fine up to 6.5 but then my arms would drop for the fatigue XD

James Douglass said...

Hi Val,

For better or worse, it's all about weight. Girls usually don't need as big sails as boys, but that's only because girls are usually lighter. If a girl and a guy weighed the same, they would need the same size sails to plane.

The calculator shows that pretty well. A 6.5 to a 132 pound person has the same power as a 9.8 to a 200 pound person- both would get their riders going in about 12 knots.


Kevin Do said...

I currently have a 150L hi fly free 279. Love it but wondering at 140lbs it might not be the best option anymore for me?

Just got a 130L fanatic shark and loving and might even buy a 105L tabou rocket. Should I keep the HiFly?


James Douglass said...

Hi Kevin,

If the Fanatic works well with your biggest sails then there's probably no need to hang on to the Hifly. You'll have a blast on the Rocket 105 when it's windy, and the sailing style for a Rocket is relatively similar to the freeride boards you're used to so it won't be a huge transition. At some point, though you might want to think about what style of highwind windsurfing you want to do. If you want to blast around and occasionally catch air, then the Rocket is good. If you want to play around with carving and jumping in the waves and chop then a freestyle wave board would be better.


Kevin Do said...

Decided to keep the hifly. Shark was easy to ride but the hifly felt exciting. Both great boards! Saving shark for choppy days. Appreciate it!

I see you're a marine bio professor. Trying to become a teacher in the marine science area. Still trying to finish ,y studies at uci in SoCal.

Marta Sánchez said...

I really think this is a very good work!...thanks a lot!...

ElTurco said...

What reference did you use to get the physics right? Very good and useful work indeed.

James Douglass said...

Hi ElTurco- Thanks! The formulas aren't based on rigorous physics. They're just equations to fit a trend curve to the empirical data. I got the original sail size formula off the Starboard Windsurfing forums, and adapted it from there. The fin size and board size equations I came up with myself.

Bryn Kaufman said...

I wonder if this needs an update for the new WindSUP Boards. I am getting a Exocet WindSUP 10' tomorrow and I am hoping to plane with my 7.5 sail in 12mph average wind. I am 155lbs.

I am pretty close to planing with my BIC WindSUP 10'6" but the BIC is not known as a good planing board so I am hoping the foot straps and the step tail and the shape give me that extra speed.

Also with the WindSUP boards it is not easy to tell when you are planing or fast gliding in my opinion. With my shorter board I am either in the foot straps and going fast on a plane or I am slogging and not able to step into the foot straps. The WindSUP has a pleasant fast glide which is kind of like planing, but not as fast I suppose.

James Douglass said...

Hi Bryn,

I don't think it's going to be much different for WindSUPs, i.e., I don't think 12 mph will be enough for you to fully plane with a 7.5, but let me know how it goes.

Good luck!

Chris said...

Hi James

I'm not sure if maybe my wind meter is out, but I find I am getting more realistic answers when I input my weight as 70 Kg, whereas I am actually 92 Kg! I do have (for the bigger sail sizes, which is where my interest is concentrating) a 2014 Fanatic Gecko 120 (77 wide) which planes unbelievably early, is that perhaps skewing things?



James Douglass said...

Hi Chris- An efficient board and good skills will definitely help. You probably have both of those things. Also, keep in mind that the calculator isn't designed to tell you the bare minimum necessary to plane. The number the calculator spits out is what's *ideal*; what will get you comfortably planing with some power to spare. So your absolute limit planing threshold might be around 2 knots lower than what the calculator spits out. Also, the wind is often less on the shore where you use your wind meter than out in the open water where you're sailing.