Something I've been wondering about. How much wind over the minimum to get planing across the wind do you think is needed to carve gybe. ie To come out of the gybe still planing, not ploughing, however briefly.
You lose a bit of speed through the turn due to extra drag and depowering the sail. That means that if you exit planing in the opposite (+/- 45?) direction you had more than minimum power to start with.
Flat water, no using a bit of a wave to help. What is your opinion? 3kts? 5kts? more?

Select to expand quote

Mr Milk said..
Something I've been wondering about. How much wind over the minimum to get planing across the wind do you think is needed to carve gybe. ie To come out of the gybe still planing, not ploughing, however briefly.
You lose a bit of speed through the turn due to extra drag and depowering the sail. That means that if you exit planing in the opposite (+/- 45?) direction you had more than minimum power to start with.
Flat water, no using a bit of a wave to help. What is your opinion? 3kts? 5kts? more?

Interesting question.

I guess we could measure this accurately with GPS, but really the answer is that it depends on your ability and your gybing technique.

Most people do lose speed when they go into a turn but if you pump the sail as you bear away and then flip the rig at the key moment then it is possible to come out of the gybe with much the same speed you went in.

In light winds, the apparent wind changes during the turn will have a bigger effect in slowing the board, so a full speed gybe is easier with rigs under 6m in size. Note that when turning a freestyle board it's possible not to lose speed but to gain speed - with the help of kinetic energy.


I've answered this off the top of my head, but I'm sure others will have something to add I've not thought of.

As said, how long is a piece of string? If you have a wide floaty board, it doesn't bog down if you loose too much speed, if you're on a small sinker, there's much less margin for error. My best alpha has an entry speed of 33kts and an exit of 15, on a semi sinker. I can still plan out of a gybe on it as long as min speed doesn't go below 10kts. On this board I need about 15kts wind to plane but 20kts + to get a 33kt gybe entry.
I can still plane out of a gybe with entry speed around 27kts, so that would need maybe 18kts?

So I'd say on that semi sinker +3kts more. And that's with a fairly tight depowered gybe, on a wider board with a powered gybe it's going to be less, but I have no data on that. I don't try for alphas in those conditions.

Select to expand quote

Note that when turning a freestyle board it's possible not to lose speed but to gain speed - with the help of kinetic energy.

Could you explain this a little more. I use a freestyle board but will lose stacks of speed through the gybe. Sometimes this is because my weight is too far back or my timing is way out. I would like to know how to maintain speeds in gusty conditions so that I come out the other side with some decent speed.

That's an interesting question. My gybes are ok because I spent many years in waves. But my alphas on a speed board in flat water are crap, I can barely get over 23 knot alpha with an entry of about 33. I reckon my footwork is the problem plus I could never judge the proximity. Where I sail mostly these days is shallow and weedy, so any tiny mistake and I start to drop off the plane, the weed drags me down. So, a couple of months back the wind was crap (12-18 knots max) and I was the only one going out, so I dragged out the old Magic Ride 104 to see if the wider tail and more floatation plus DIY-GPS helped with alphas. I had a bunch over 20 and a best of 22.2 with an entry of 25, turn at 12, exit at 20. I reckon if I had persevered I might have got a PB alpha, which is a bit embarrassing given the board and conditions.

Select to expand quote

MarkSSC said..

Note that when turning a freestyle board it's possible not to lose speed but to gain speed - with the help of kinetic energy.

Could you explain this a little more. I use a freestyle board but will lose stacks of speed through the gybe. Sometimes this is because my weight is too far back or my timing is way out. I would like to know how to maintain speeds in gusty conditions so that I come out the other side with some decent speed.

Well, firstly let's assume you are sailing a board that floats you easily, and is not a sinker. Having at least 20litres of positive float over your body weight in kilos is a very good idea for this.


Then, when you do a standard gybe on flat water, you can lose speed for two reasons:
1) As you bear away from the wind for the turn the wind flow across the sail can stall, with the 'apparent wind' changing direction. Remember that the apparent wind is the combination of the true wind of the day and the 'created' wind that comes from the board moving forwards. The sail thus loses drive as you turn downwind.
2) As the rig loses drive because of point 1) your stance on the board must change or else the board will no longer be flat. In other words, most people lose speed further in the turn because they keep their legs straight and just stand there, and the board tail inevitably sinks, stalling planing speed.

You can overcome the above two problems in three or four ways:
1) Pump the sail as you go into the turn to maintain planing speed and to help keep apparent wind flow across the sail. If you go into the turn with full power you should even be able to stay well sheeted in until the moment of the rig flip.
2) Lean well forwards to keep the board level and change feet at exactly the right moment before the rig flip, and without unsettling the board trim. (We call this a step gybe.) If you are leaning forwards well enough then occasionally you will go over the font. If you often fall in backwards with your gybes then clearly you are leaning too far back.
3) Steer a course of least resistance through any waves of chop, making sure the board is heading 'downhill' for the rig flip stage. This idea is still a thing on flat water, even on a choppy lake. The skill is in reading the water ahead of you, like when cycling downhill on a steep and bumpy road.
4) There are several hand options for a rig flip, but if you can flip the rig at the last minute you can sometimes catch the boom on the new tack when the board is already heading off in the new direction. If the rig than arrives in your hands with full power on the new sailing course then you can use that new power surge as a sling shot effect to accelerate away.


Hidden away within all the above is what you are doing with your body. By bending the knees, shifting your weight, and pumping the sail with your arms, you are using kinetic energy to maintain or even to increase board speed. Each body movement works in harmony with the apparent wind changes in the rig and with the changes in board direction as it arcs through the turn.
It also helps if you have a picture of all this in your mind, so that you can make it happen. Imagine yourself planing through the gybe at speed and, if you get the body moments right, you will.

I'd like to see the GPS plots of a sailor who can exit with more speed then they enter.

Select to expand quote

Grantmac said..
I'd like to see the GPS plots of a sailor who can exit with more speed then they enter.

So would I.
I'm thinking the sailors most likely to do it would be on a freestyle board.
But we definitely need proof.

I think this was 12knots avg, gusting 15. Minimum speed in the gybe would be 7 or 8 knots, the video software averages the last 4 seconds to get a smoother display. Some gybes I was entering at 18 and just about kept moving. A gust and entry speed was 22 knots. 8.5m sail and 125l board. 46cm upright fin helps, don't believe what some wave sailors tell you. So for big kit, for me when it's 12 average, I can get planing without pumping in a little more and do planing gybes.
I had a Goya One 85l, 2015, and that was so slow I could only plane out of gybes if we'll powered up, single fin, thruster, whatever.

Select to expand quote

Basher said..

Grantmac said..
I'd like to see the GPS plots of a sailor who can exit with more speed then they enter.

So would I.
I'm thinking the sailors most likely to do it would be on a freestyle board.
But we definitely need proof.

Going down a dead end with this one. If you can exit with more speed you should have been going faster in the first place. It's nonsense.

On my wave boards (onshore biased but not FSW) I basically can't plane out unless I'm borderline overpowered unless there is enough swell to glide down.
On a FSW it's more possible on flat water but still needs enough wind to passively plane.

I haven't sailed anything more efficient than those categories in years except foiling which is cheating.

Select to expand quote

decrepit said..
As said, how long is a piece of string? If you have a wide floaty board, it doesn't bog down if you loose too much speed, if you're on a small sinker, there's much less margin for error. My best alpha has an entry speed of 33kts and an exit of 15, on a semi sinker. I can still plan out of a gybe on it as long as min speed doesn't go below 10kts. On this board I need about 15kts wind to plane but 20kts + to get a 33kt gybe entry.
I can still plane out of a gybe with entry speed around 27kts, so that would need maybe 18kts?

So I'd say on that semi sinker +3kts more. And that's with a fairly tight depowered gybe, on a wider board with a powered gybe it's going to be less, but I have no data on that. I don't try for alphas in those conditions.

In at 33, out at 15. Kinetic energy is proportional to the square of speed. You lost 80% of ingoing kinetic energy. Gybing a slapper is all bout minimising hull drag. Have you noticed how much easier it is to gybe in shallow water? Ground effect minimises hull drag. Also makes trim easier. Too much weight on the tail more ground effect at the tail end. Self trimming.

Select to expand quote

Grantmac said..
I'd like to see the GPS plots of a sailor who can exit with more speed then they enter.

If that's the sailor only without the gear, I can show you that

Select to expand quote

Grantmac said..
I'd like to see the GPS plots of a sailor who can exit with more speed then they enter.

If that's the sailor only without the gear, I can show you that

Not sure if the video will load. Here is actual GPS data of a Gybe (Aus Record for an Alpha) shows his speed in at 35+ knots you will notice how much speed is washed of in the turn. This is typical of all Gybes.

Glad to know I'm not the only one that loses a bunch of speed in gybes, although mine is more like in at 20, out at 2.

IMO, the stronger the wind, the greater the chance of maintaining speed provided you execute a tighter gybe radius and keep your body weight forward and over the mast foot to maintain speed as it keeps the board more level.

Here is an oldie but goodie, this is the fastest recorded Alpha +30 knots, one of the fastest speed sailors in the world watch the k's drop in the turn I've got some hope
?t=33

Just to repeat something here:

It's important to say what sort of board you are on, and it's size in relation to your weight.

On a speed board, you might have built up to going very fast - perhaps with an over-sized sail - but that speed is unlikely to be carried into a true for a fully planing gybe. That's because a speed board is very narrow and, similarly, your fastest slalom board will usually be your narrower one. A narrow width helps for top SPEED, but the wider boards generally do better for ACCELERATION.

A wave board is also unlikely to plane right through a gybe unless the turn is wave-assisted. But of course the float of the board and its rocker line also has some say in this.

Freestyle boards are the most efficient designs for keeping speed in the turns because the typical 100 litre freestyle board has a slalom rocker line, a 65cms width, a wide and fat weight-carrying tail, and is used with 5.2m sails or smaller by a 70kgs rider.


If we all had the same perfect technique, hahah, note that the lighter sailor would be the one most likely to plane right through a gybe on any of the above gear.
But of course, and on topic, wind strength has a say in this too.

Select to expand quote

Basher said..

Grantmac said..
I'd like to see the GPS plots of a sailor who can exit with more speed then they enter.

So would I.
I'm thinking the sailors most likely to do it would be on a freestyle board.
But we definitely need proof.

Woodymark might have one.

I guess it depends on if you are talking about a general gybe or an Alpha and how many metres before and after the apex we are talking about about.

Select to expand quote

Basher said..
Freestyle boards are the most efficient designs for keeping speed in the turns because the typical 100 litre freestyle board has a slalom rocker line, a 65cms width, a wide and fat weight-carrying tail, and is used with 5.2m sails or smaller by a 70kgs rider.

Slalom boards have short planing flat, freerace have a longer one. A larger board has more glide, think skimming stones, wider is better. Slalom and freerace have wider tails than freestyle.

You don't know which is more efficient as you haven't measured it.


Ps, if you tried a modern larger slalom/freerace you might have a different opinion. They aren't the monsters of last century.

Select to expand quote

remery said..

Woodymark might have one.

I guess it depends on if you are talking about a general gybe or an Alpha and how many metres before and after the apex we are talking about about.

Actually the speed plot above is Woodies Aus Record Alpha

Regarding Speed versus Slalom vs Freeride I can nearly guarantee that if you put a proper GPS on to measure your speed on each type of board will show some slowing of speed in the turn, how much well depends on how good you are at gybing

The 30 knot above yes was a speed board, the 29 knot alpha was a high wind Slalom 56 wide, other gybes in the high 20's done on 98L 62 wide slalom.

Not sure what you mean by freestyle? Is that the ones you do those twirly jumpy tricks on?? They are not very quick boards from what ive seen maybe if you go in at 14 knots you can come out at 14 knots

Simple just put a proper GPS on you'll find out fairly quickly that perception of speed of what you think you doing and reality are two worlds apart.

Is that the video that's not showing up? (Aus Record for an Alpha). I feel bad talking about Woody's alphas without him contributing. I've spent hours trying to figure out how he does it.

Select to expand quote

remery said..
Is that the video that's not showing up? (Aus Record for an Alpha). I feel bad talking about Woody's alphas without him contributing. I've spent hours trying to figure out how he does it.

Yes Rob it's the one, have a look now my bad had private on it

Select to expand quote

Grantmac said..
I'd like to see the GPS plots of a sailor who can exit with more speed than they enter.

Assuming this just a Gybe we are talking about, and not an Alpha?
Well I will go on record as saying it definitely CAN'T be done.
The very idea defies the laws of Physics. The moment you turn more than 25 degress or so downwind you will start to slow down

Now produce a GPS track and prove me wrong.

For an Alpha on the other hand...... that is definitely possible if you take the start and end speeds at the proximity circle and ignore the drastic slowdown in the gybe.

Here is an example by a little old 72KG man on a slalom board and 5.2m race sail in about 25 knots of wind :


Edit: The speed graph and video starts before the 500m circle and continues beyond the end of the 500m. Entry speed was about 29 knots and exit speed at the Proximity circle was about 32kts.

Select to expand quote

Ian K said............... Have you noticed how much easier it is to gybe in shallow water? Ground effect minimises hull drag. Also makes trim easier. Too much weight on the tail more ground effect at the tail end. Self trimming.

According to the WSSRC, ground effect does not help you until the depth of the water is less than half of the beam.
On almost any board and situation I can think of, that is very close to the fin depth which means you are in grave danger of running aground.
I'm not entirely sure the WSSRC is correct on this, but I can't say I have actually noticed 'ground effect' in all my shallow water windsurfing, at least not except for the instant before a very bad crash!!

What I can say with lots of experience it that extreme flat water (think glassy, weedy lakes and low wind speed), definitely minimises hull drag and makes flat trimming and retention of planing speed easier.

Select to expand quote

PhilUK said..

Basher said..
Freestyle boards are the most efficient designs for keeping speed in the turns because the typical 100 litre freestyle board has a slalom rocker line, a 65cms width, a wide and fat weight-carrying tail, and is used with 5.2m sails or smaller by a 70kgs rider.

Slalom boards have short planing flat, freerace have a longer one. A larger board has more glide, think skimming stones, wider is better. Slalom and freerace have wider tails than freestyle.

You don't know which is more efficient as you haven't measured it.


Ps, if you tried a modern larger slalom/freerace you might have a different opinion. They aren't the monsters of last century.

Well, true, none of it has been properly measured, and we're all just shooting the breeze here.

But I did sit and watch world class slalom sailors race against world class freestyle sailors in Cape Town on the windy lake, and the results were quite amusing. The slalom sailors had the better top speed, but the freestylers would pick them off at the marks or in any wind lulls.

The typical set ups for these two types of boards are of course like chalk and cheese. The slalom guys were on 7m rigs when the freestyle boys were on 5.2s. That difference alone should have us scratching our heads.

The slalom gear reaches top speed when you fly it off the fin and so that board will inevitably slow down when it starts to turn and has to plane more off the hull rocker flat. The freestyle board is not driven off the fin so much in the first place, and so its acceleration is down to the sailor working the hull and sail, and the average speed through a turn doesn't change so much.

On the occasion I was observing, it was also interesting to see which of the freestylers was fast in a straight line. Some of the top guys were really fast, even on their short fins, whereas some of the others clearly didn't like to go fast.

Select to expand quote

Grantmac said..
On my wave boards (onshore biased but not FSW) I basically can't plane out unless I'm borderline overpowered unless there is enough swell to glide down.
On a FSW it's more possible on flat water but still needs enough wind to passively plane.

I haven't sailed anything more efficient than those categories in years except foiling which is cheating.

Similar for me, with wave board i need to be at least nicely powered up if its not choppy, close to overpowered if its choppy. I olso find it easier to plane out with duck jibes if entry speed is good.

Select to expand quote

sailquik said..

Ian K said............... Have you noticed how much easier it is to gybe in shallow water? Ground effect minimises hull drag. Also makes trim easier. Too much weight on the tail more ground effect at the tail end. Self trimming.

According to the WSSRC, ground effect does not help you until the depth of the water is less than half of the beam.
On almost any board and situation I can think of, that is very close to the fin depth which means you are in grave danger of running aground.
I'm not entirely sure the WSSRC is correct on this, but I can't say I have actually noticed 'ground effect' in all my shallow water windsurfing, at least not except for the instant before a very bad crash!!

What I can say with lots of experience it that extreme flat water (think glassy, weedy lakes and low wind speed), definitely minimises hull drag and makes flat trimming and retention of planing speed easier.

Can't figure out how to drag images on a smart phone, but just google "ground effect height vs wingspan". The How to fly a plane manuals all seem to use the same graph which shows an asymptote to zero. At half wingspan the drag reduction is 8%. Maybe I'm imagining I can sense that.

Of course perceptions are known to be biased towards what you believe should be the case.

Select to expand quote

sailquik said..

Ian K said............... Have you noticed how much easier it is to gybe in shallow water? Ground effect minimises hull drag. Also makes trim easier. Too much weight on the tail more ground effect at the tail end. Self trimming.

According to the WSSRC, ground effect does not help you until the depth of the water is less than half of the beam.
On almost any board and situation I can think of, that is very close to the fin depth which means you are in grave danger of running aground.
I'm not entirely sure the WSSRC is correct on this, but I can't say I have actually noticed 'ground effect' in all my shallow water windsurfing, at least not except for the instant before a very bad crash!!

What I can say with lots of experience it that extreme flat water (think glassy, weedy lakes and low wind speed), definitely minimises hull drag and makes flat trimming and retention of planing speed easier.

Can't figure out how to drag images on a smart phone, but just google "ground effect height vs wingspan". The How to fly a plane manuals all seem to use the same graph which shows an asymptote to zero. At half wingspan the drag reduction is 8%. Maybe I'm imagining I can sense that.

Of course perceptions are known to be biased towards what you believe should be the case.

I'd like to see someone good do a duck gybe alpha. I remember minimal speed loss when I used to do them on a wave board. I use the term "speed" loosely :)