How much wind needed for 47 knots speed?

My friend Gestalt asked this question in another thread:

"hey sailquik, in your opinion, how windy would it need to be to do over 47knots gps?"

It was off topic in that thread so here is my answer in it's own thread.

It depends a lot of course on the sailor's size and the course. Generally, Larger sailors will go faster in a given amount of wind, all else being equal.

Assuming, the ideal angle to the wind (around 130-135 degrees off the wind) and flat water:

In the heyday of Sandy Point (up until about 2014) when the spit was very low and smooth and the wind was laminar right to the sand/water, there were plently of people who did 47+ Peaks in actually measured, 35 to 40 knots of wind. When Chris did the first 50 peak, (around 2008?) I would be very surprised if the squall he did it in was more than 40 knots. The winds in these squalls were fairly solid and consistent with not much more than 5 knots variation over the short term. Let me assure you that a solid 35 knots of wind right to the water surface has a lot of force with sand blasting and water spray. Here is a 30 knot day in 2008 where speeds were in the low to mid 40's:



Of course there were days with stronger winds, and we tried to go faster in those with limited success. Getting started and surviving on the run in is difficult. The most memorable of thse days was 27-09-09 durfing speed fortnight. On this day the wind was consistently over 40 knots and we saw prolonged squalls to 50 with gusts to 60 knots. This was more like survival than speed sailing, which anyone who was there will certainly confirm. The biggest guys, Tony and Spotty both did exceptionally well with the smallest sails they had ever used (4.4m and 5.0m respectively). Spotty a 50 peak and Tony a high 49. and they did mutiple runs at close to those speeds. Some of the rest of us got PB peaks just by surviving one or two runs. Of course, we were all looking for the lulls between the strongest squalls, then hunkering down in between.

There are plenty of pictures around of that day thanks to Jody of Whitecaps photography.

Spotty going for a 50 in a Lull:



Here is a very brief video taking in one of the squalls. (I think by Izaak Perkins?)

The caption is incorrect for this short segment, it should say gusting to 55 knots.

Luderitz is a very different situation as the wind there is a LOT more variable and turbulent, as it comes over an undulating rocky desert.
I tried to get my head around it with the help of Anemometers but it is very hard to quantify. The best I can do is to say when I did my 47 peak, Jacques his 49 and Tony has 50, the wind was mostly between 30 to 45, but with large variations over even a few seconds.

Here is one run from Tony with the wind gauge showing between 30-45 knots (The wind is even more variable and a bit lighter in the start area)



An another vid where I was using two anemometers:



There were definitely times on our trip when the wind was stronger, but on this day, too broad for us to safely run the course.



And we must remember that few sailors (notably Brad Anderson and Hamma) have done 47 peaks, or very close to it at Lake George. On those days I would be astounded if the wind was over 35 knots at any time, and was mostly in the low 30's max. (I was sailing pretty much to whole day when Brad did his 47). Much over 30kts of wind is a very rare thing at LG on a SE and I have yet to see it. If we ever get a day with the right water conditions and 35+ knots of SE wind there, I recon the record books will be obliterted.

And what board sail fin would one want to use.

^^ sboardcrazy. This thread we are reading. I called it an article coz it had good info n pictures n vids. Almost like a magazine article....

Im still a greenhorn, 2nd year back after 30yr break. But Windsurfing has always been about MAX SPEED for me... Im in awe of the Big names speeds. But even better is, GPSTC shows just how many great aussie sailors are RIGHT UP THERE with the Worlds best. Its great to be able to get tips on technique n tuning from guys who have done it. The more i learn the more im obsessed to go faster. MUST LEARN TO GO FASTER n FASTER.....

Kato, LG Primbee Sandy Pt etc . In the process of selling up my other toys to fund a trans OZ windsurf basecamp vehicle. Then go check it all out.