May I ask as start to learn speedsailing - for wind speeds of 18 - 30 kts, what gps speeds should I be aiming to reach as respectable ? Is there a typical ratio discount, like achieving 23 knts in a 25 knts gust ? No one else around me speedsails so I dont have a sparring partner to compare.

There is a wide variety of variables that drastically alter the idea of what is respectable. eg: water state, wind speed, equipment, your weight etc.

the only useful intel that I have garnered from a brief amount of time trying to go fast/er is try to go faster than everyone else




bit daunting when you've got Slowboat hammering down the sandbank at 40+knots regularly at your local, but you've got to have something to aim for, right?

To be a little more serious, I started out by aiming to hit 30knots on the flat water, so maybe that's a start?

It's a sliding scale if you have the right gear for the conditions, you can do double the wind speed. eg at 12 kts you can do 24.
But at 20kts you can't do much more than 30. it takes about 30kts to do 40 and about 50kts to do 50.
As said this varies with conditions and rider.
There is slow water and fast water, the numbers above are what I can do in very good conditions. and I'm somewhere around average.
apart from the 50 in 50. I haven't come across those conditions, and I'm now too old to think about it. also 24 in 12, I don't have suitable light wind gear.

So in 18 to 30kts you should be getting close to 30 at 18 and close to 40 at 30.
23kts is not speed sailing.

In smooth water, I reckon 36 knots in 18 is good going.

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remery said..
In smooth water, I reckon 36 knots in 18 is good going.

Slowy may be able to do that, but nowhere near it for me.

checked all my 36 runs and wind was more around 25 , with 5.2 or 5.8 sails

Yep, that's me 25kts to do 35

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decrepit said..>>>>
23kts is not speed sailing.

If we're talking about 2s average, that most of us are.
However if you're talking about an hr average 23kts isn't too bad.
Likewise an alpha.

I was thinking of 2sec speed on those days where the forecast was 12-18.

The sliding scale is correct. A summary of 4 days results from this year's trip to Lake George follow:
Date, Board, Sail, 2 Sec, Max Wind, Multiplier
3 Feb: Falcon 115, 7.7, 29 kts, 14 kts, 2.1
2 Feb, Falcon 97, 7.0, 34 kts, 20 kts, 1.7
4 Feb, Falcon 97, 6.2, 38 kts, 25 kts, 1.5
5 Feb, JP 80, 5.7, 40 kts, 30 kts, 1.3

Thank you John340, that sets out very clearly an approx range of speed goalposts for me plus the outline kit selection. Gunna nail it to my garage door. Ive got a long way to go.

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Jasonwave said..
Thank you John340, that sets out very clearly an approx range of speed goalposts for me plus the outline kit selection. Gunna nail it to my garage door. Ive got a long way to go.

Yeah , and it's ace fun. Cracking 30 is a milestone. After that your chasing super flat water , which you need to safely go faster.

Jason, you say there aren't speed sailors where you sail.
Speed sailors will usually travel to good speed sailing spots, (like wave sailors are attracted to good waves). This could be you don't have good speed sailing conditions. If that's so, you may not have as far to go as you think.

Lake George can have mirror flat water at 15kts, and no whitecaps at 30kts.
So if you don't have good conditions you won't be going as fast.

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decrepit said..

Slowy may be able to do that, but nowhere near it for me.

I might have been embellishing (again). I was thinking of 14 Jan this year when I did a little over 34, when BoM measured 3:00pm wind at 12 knots. I got in a gust that was probably way more than that, but the water was shallow and smooth. I guessed that 18 and 36 was doable.

I got very close to a 32, so it was probably a good 20kts.
The Mandurah anemometer is in wind shadow with a SW, so it under reports windspeed big time.

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Jasonwave said..
Thank you John340, that sets out very clearly an approx range of speed goalposts for me plus the outline kit selection. Gunna nail it to my garage door. Ive got a long way to go.

I weigh 87 kg. If you are lighter or heavier, you'll have to adjust gear accordingly for wind speed.

Flat water and sailing at approx 130 degrees to the wind are essential for max speed.

Do you have access to flat water? Do you understand the concept of bearing off the wind?

There as a few good Youtubers out there who can provide good tips, eg Nils Bach

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John340 said..
The sliding scale is correct. A summary of 4 days results from this year's trip to Lake George follow:
Date, Board, Sail, 2 Sec, Max Wind, Multiplier
3 Feb: Falcon 115, 7.7, 29 kts, 14 kts, 2.1
2 Feb, Falcon 97, 7.0, 34 kts, 20 kts, 1.7
4 Feb, Falcon 97, 6.2, 38 kts, 25 kts, 1.5
5 Feb, JP 80, 5.7, 40 kts, 30 kts, 1.3

Very approximately - take the square root of 55 * wind speed

It's interesting that it's reasonably close over a 2:1 range in wind speed. Wind power force increases with the square of wind speed. Drag is a combination of square terms and semi-linear terms (skin drag, planing hull drag)

Although we all have experienced this, it feels mathematically counter-intuitive that the bigger gear, with more skin drag and lighter winds is more efficient.

I suspect the factor I've always overlooked is that the hydrodynamic drag terms are scaled to the board speed, while the aerodynamic drag terms are scaled to the apparent speed, not measured wind speed! As the wind picks up and overall velocity increases, the aerodynamic drag forces increase significantly more than the hydrodynamic drag forces. This will be especially true for upwind courses vs. downwind courses.

I was chatting to Boz about this and he reckoned about 12-13 above wind speed as a general indication. Since then I've taken notice of this and agree. Also Alpha and HR results seem to be similar and a reasonable alpha is about six knots below the 5X10 average speed.

Got it, thanks. In short :

Target 1 : break 30 knots in whatever wind. That will have me singing in the shower

Target 2 : break 30 knots in 20 knots of wind. You will all hear me singing in the shower

I have flat water so no excuses.

big respect to you lot that have it nailed down.

Take it as a learning experience without thinking too much about the numbers, the journey often is better than the destination. You need a small slalom board, slalom or freerace sails and some good fins for improving. Then spend time to tune the lot so it is balanced.
Get a gps device and analyze your track in GPS Speed Reader. The actual speed run is the easiest part, you just sit on your gear , bear off and enjoy !

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ozzimark said..

Although we all have experienced this, it feels mathematically counter-intuitive that the bigger gear, with more skin drag and lighter winds is more efficient.

All your points are valid, but I think there's another that you've overlooked. The ratio of sailor area to sail area.
light winds big gear the sail area is high, strong winds smaller gear ratio is lower.
And theoretically power is constant, it's directly related to sailor weight.
Whereas drag increases with speed.

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Jasonwave said..>>> I have flat water so no excuses.

So out with it!
Where are you, tell us and you may get some company.
Flat water is in short supply this time of year.

Am in southern Portugal, waiting for the summer breezes to come thru. You are welcome to come join, mostly wingfoilers around me. A couple of slalom lads pop up when conditions are perfect, then I have to pull rank as the strip is narrow.

I have been to Portugal, and would love to sail there. But i'm wondering if your idea of flat water is the same as mine. I think of flat water as chop less that 10 cms. Speed is easy in that kind of water;

Thanks all. 25 knts in around 20 knts gusts. 7m, 100L Futura for my 78 kg. Standard 32 cm fin. Comfortable to hold once going, slingshot part a bit bumpy in 20-30cm tight knit ripples with 4knt tide into wind. Couldn't get the railing going to hop over them.

I thought the 2 local speed lads were just lazy as they were out only 30 mins either side of high tide. Turns out, that unlike me the rookie, they have an affection for their fins, board nose, ribs and battens. I now know where the sandbanks are hiding. Gunna keep the local repair man busy.

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Jasonwave said..
Thank you John340, that sets out very clearly an approx range of speed goalposts for me plus the outline kit selection. Gunna nail it to my garage door. Ive got a long way to go.

That's assuming good flat water.If you're sailing out in chop it will be a lot less.

21/12/24 Albany

25-26 knots in 12-14 knots of breeze

You've started a Liptons longing here.

Water that flat is unfair.