am not really into speed all the time but check this out looks like the 'ground effect' thing is a fact
The WSSR Council announces an amendment to WSSR Rule 3.
3rd paragraph is amended as follows:
"For every record attempt on natural courses in every class, there must be a minimum depth of water, which is defined as follows.
At the time of the run in question, the shallowest part of the course must be covered by water with a depth of at least half the static immersed beam of the craft involved, or 10cm, whichever is the greater.
(Guidance note) To define the depth requirement, the craft or board involved should be afloat and the widest part of the hull or hulls touching the water should be measured. In the case of a multihull, the widest hull is measured or hydrofoil if fitted. In the case of an event involving a number of competing craft, the WSSRC Observer can announce at the commencement of the event what the minimum depth requirement will be"
Reason:
The WSSR Council had introduced the "50 cm minimum depth rule" after having commissioned an investigation from Southampton University's Wolfson Unit into the ramifications of "ground effect" on craft sailing in shallow water. This report had concluded that ground effect can indeed have a marked effect in reducing the drag of craft sailing in very shallow water, that it became significant at a depth factor of half the beam of a planing surface and that in general a minimum water depth of 50 cms would be more than deep enough to avoid this shallow water effect. In general, the sport had welcomed this ruling as it posed little or no practical problems.
Kitesurfers and Windsurfers however had a major difficulty in administering this new rule, to such an extent that it threatened to bring their attempts on records to a complete halt. These craft have traditionally used tidal courses, close to the shore since the 1980s, when the Weymouth Inshore course was established, Subsequent venues around the world - all verified by the WSSRC - had adopted this format of which the greatest advantage had been the ability to sail in smooth water. But by the physical nature of these courses and due to geographical and tidal effects, the depth of water varied considerably along the 500 metre length and thus complying with the 50cm rule overall could make it impossible to set courses, without ending up well out to sea, in conditions adverse to high speed.
All accept that "ground effect" exists and are unanimous that it should not be a factor in setting records. There was a danger that artificial courses might be created which could take advantage of this aid to higher speed but this was a separate issue which the WSSRC would address presently. However, in considering the Wolfson Report, the measurement at which ground effect came into effect was at half the beam of the board. As the average width of a board was 20 cms, it seemed reasonable to establish 10 cms as being the absolute minimum depth for natural courses - as opposed to manufactured courses - at the shallowest point.
Sorry JP, you're a bit behind the times, we've had a huge discussion about this to the point of irritating some of the regulars
Ground effect can have a marked effect in reducing the drag of craft sailing in very shallow water.
Reduced drag means: The sailing craft becomes faster.
The WSSRC has the opinion that its wrong, that a sailing craft becomes faster with the help of the ground effect.
But they don’t tell us, WHY this should be wrong. No technical reason whatsoever. They just say: ALL are unanimous that it should not be a factor in setting records.
That leads to two questions:
First question: Who is ALL? All three ? Markus, Pete and Dave ?
Second question: It SHOULD NOT BE is just an opinion - what is the reason behind this opinion ?
I understand, that my rivals cannot stand the fact that I have broken the 50-knot-barrier in January and that they wish that it had never happened. And that they are very afraid I would do it officially next winter. So they obviously have two ways to handle it:
1) Drinking
2) Changing rules
But drinking and changing rules at the same time is not good. ;) You see it from their reasons for the new water depth rule: Just brainless feelings... but what is REALLY wrong with the ground effect ? No answer...
Here my advice to all my rivals: Stop this nonsense, stop changing rules. Its nothing else than an absurd contradiction to the original spirit of speedsailing ! The world is laughing about that.
Better look for your own liquid ice spots ! They are everywhere all over the world, where you have wide and flat beaches. Just watch how the conditions change between the tides and you will see perfect strips emerge and disappear again.
Kiting in 5 cm is still sailing. You can even go upwind. So nothing forces you to sail in deeper water – there is no reasonable reason for it.
Riding on liquid ice is a wonderful feeling. Its not like surfing anymore. More like rolling over a highway. No bumps whatsoever. You hardly feel any effort, because all forces are in a perfect balance and there is almost no drag. Its so exciting and adrenalin-pumping to fly with 50 knots over 5 cm of water ! Thrilling – but not dangerous. Because the kite holds you, if you fall.
Speedkiting on liquid ice is new, beautiful, exciting and simple-natural.
Its definitely the last step in the evolution of speedsailing.
And future kiters will set unbelievable new records on liquid ice.
I'll probably drop into this forum from time to time, depends how much the internet cafes cost
oops hards and depcrep really thought it was more of a theory than fact
but it's a nice read for changing rules here and there
I'm with Tilmann here. Drag is reduced with shallow water which leads to greater speeds. When speedsailing the aim is to achieve maximum speed. Why then rule against what the players are seeking to achieve. The playing field as far as "ground effect" goes is level (pardon the pun). Every player can use ground effect so why disqualify this particular effect only. Leaves the WSSRC AND the GPSS/Windsurfing representatives looking like sore losers and for me at least "proves" that the WSSRC recognises that 50 knots has already fallen.
but it's a nice read for changing rules here and there
The point is that not every player can use ground effect equally and the WSSRC has made a ruling. They did listen to the guys who run the GPSS ladder and amended the ruling such that it did not penalise smaller craft (kites and boards) over bigger ones.
The logical extreme of the "round effect" arguement is that we would need to include someone recording speeds on ice. The pressure exerted by the sharp edge of iceskates creates a thin film of liquid water that lubricates the relative movement of skate and ice. This meets the logical definition of "sailing" - movement as a result of the action of the wind in the sail and water on the hull (skate).
I suppose WSSRC have the right to make rules as they see fit, as do the GPSSS guys. The fact that kites were never eligible for the "World Speed Record" as they oversee, means that Tillmans "record" was never valid anyway - so he is not being additionally penalised for using "liquid ice" or ground effect. Likewise GPSSS's speeds are not valid for world records either because of issues with the accuracy of handhelp gps's. They are working with the WSSRC to demonstrate accuracy levels to the satisfaction of WSSRC, not demanding that rules be changed to include them.
If you dont like the rules as set down byother organisations, then create your own organisation and rules. That was an option when the initial ruling about water depth was developed and remains an option for anyone who feels they (or their craft) are still unfairly excluded.
JB
I see this chestnut has surfaced again and seems no closer to being cracked.
First let me say, welcome Dr Speed (Tilmann) to this forum. anyone who can do 50knots under sail has my respect whether it is on water or liquid ice ( thin film of water over a solid surface.
And this seems to be the distinction between the two camps. Some , myself , Slowboat and the WSSRC etc feel the craft should be supported solely by water (bouyantly, hydrodynamically or a combination of both). Others..Tilmann , Frant , Sailquik etc feel that as long as the craft is on water it doesn't matter if the water itself is supported by the ground underneath it. They feel it is still sailing, I and my side also feel it is still sailing but not sailing on water (but water supported ie a lubricating layer).
Anyway, as it stands, it is the WSSRC that makes the rules and they also feel ground effect is not sailing on water. Unfortunately (for me, windsurfers and other sail craft BUT not kiters) they have made a real stuff up on this water depth rule.
The actual effect of rule as it is written is that they have legalised sailing in ground effect for kiters (the very craft that can do this most easily) and banned it for everyone else. I hope this is just because they don't understand the physics involved and not because they have capitulated to pressure from the kiting community.
Very nicely put Frant, and I must point out that I do agree with you on these points.
Perhaps the research of the Wolfsen Unit should be made public (I stand to be corrected but I dont believe it has been published) so that we can debate the actual impact of "ground effect" properly. Perhaps then we could also determine the actual impact of the effect on speeds and see what the depth/width ratio actually results in.
The sad thing is that I dont think it is possible to have a ruling that will make everyone happy. If we allow sailing in a few cm of water then we risk the creation of multiple record categories (even more then we already have). So we would have 1 record for kites, one for boards, one for dinghies, one for yachts under 1 tonne etc etc.
At least the WSSRC has shown that they are willing to listen to arguements and are willing to amend rules if required. Instead of people saying the rules are unfair, perhaps we need to offer solutions to the WSSRC. The GPSSS guys pushed their own agenda and got a result that satisfies them. If this doesnt satisfy others that is their agenda to push.
I agree that the merits of pro and anti ground effect discussions are required, but any outcomes need to be acceptable to all camps - including MI, Sailrocket etc. Any proposed change that does not meet the requirements of all parties will not carry much weight with the WSSRC as they will be viewed as self-interest.
The WSSRC should be presented with solutions, backed up by clear and open debate. Bashing them will alienate us in their eyes. If they believe that "Ground Effect" has a large impact on speed, then we need to debate the science and present them with options based on fact rather then opinion. Telling them over and over that it has little effect is a pointless position to take.
Their ruling may have been kneejerk, but it has been made nonetheless. I dont think they will make any further changes unless we offer them an opportunity to save face (*in the event that the science says that the findings are not correct).
WRT your dilemma about your and slowboats run down the same course - rules are rules. Not what you want to hear I know, but nothing is stopping you sailing, only submitting your results to the WSSRC. Similarly nothing is stopping Tillman sailing either. If we dont play within the rules we either play alone or create our own new rules.
JB
Tilmann said...Riding on liquid ice is a wonderful feeling. Its not like surfing anymore. More like rolling over a highway. No bumps whatsoever. You hardly feel any effort..
This why the WSSRC doesn't regard it as sailing on water.
This is the benefit gained. L/D increases from 6:1 to 12:1 (100%) with ground effect. L/D increases from 6:1 to 19:1 (>200%) with ground effect with end plates (kite board with fins on edge).
http://www.sailspeedrecords.com/the-course-of-half-a-kilometre.html
Edit : where is this new rule you speak of?
No debate from me, or Frant as I understand him, that sailing in 'ground effect' reduces drag.
The debate is about whether this is sailing on water.
We say 'yes', it is still sailing, and on water. Therefore it is a biased and nonsense rule.
As long as the hull or fin of the craft gains the lateral resistance to sail from foil action in only water we see it as sailing.
Ice boats do not do the above. They use a groove in the ice for lateral resistance. There is no foil effect on the water. They are not sailing on water. An east distinction to make.
The last thing a record body should do is consult the existing record holder about changes to rules or limitations on other craft. That is just daft. All the major players are biased against any craft that might beat them. Unfortunately, I think that is exactly what has happened here. Years ago there were groups in the sailing fraternity who didn't consider windsurfers 'sailing craft' and wanted them banned. Likewise others wanted use of canals banned. It goes on forever.......... The only difference not is that, for some reason, the WSSRC has decided to listen to those pushing bias and actually respond to it with a biased rule to protect certain interests.
On the 'liquid ice' quotation; I think this was an unfortunate choice of phrase by Tilmann as it immediately gives rise to suggestions that it is somehow like 'ice sailing' when in fact it is not at all like that. The quote that it is very smooth is also irrelevant. This is what all sailors strive for. Smooth water. This is why we sail close to the bank. This is why a canal was built. This is exactly the feeling we get on a good run at just the right tide and wind angle at every good speed sailing venue on a windsurfer.
The GPS-SS guys did not 'get what they wanted'. The ISWA got what they wanted, or at least what the most vocal of their members wanted. If they had not, it is highly probable that another speed record body might have been set up. I would certainly not say the matter is settled. It could still cause the formation of a new record sanctioning body. I suspect many are gathering their thoughts and waiting to see how it all works before deciding on whether to pursue other options. If this debate irritates you, well, you will need to find a way to chill out because it has a long way to go yet.
Looks like Tilmanns done it again and will manage to get a few more people offside (GPSSS Forum). I wonder if the enthusiasm with which the minimum depth of water rule has been instigated has anything to do with the apparent abrupt and Germanic manner of Mr Tilmann. I can't imagine that his manner has won him many friends within the WSSRC council.
And let me state for the record I don't think that kiting is sailing unless you happen to like standing with your back to the wind being dragged along by string with practically no control over the kite. However I must concede that it satisfies the definition of sailing and should be eligible to claim the prize.
But the rule has been rigged hasn't it. Windsurfer needs at least fin depth plus a safety margin so the rule doesn't come into play. We're all right Jack! Must be a good rule then.
The ground effect doesn't just switch off at 1/2 beam depth. why not set the rule to full beam depth or 1/10 beam depth. No we will just choose a depth that frustrates our kiter friends. Had they made the minimum depth absolutely 50mm everyone could be happy.
The WORLD SAILING SPEED RECORD should be eligible to any craft irrespective of what proportion of drag reduction it can obtain from ground effect. Otherwise it just not cricket er sailing
Ok I'm bored and I've been sucked into the debate.
When we speak of records, we're hardly comparing apples with apples, therefore there must be different classes, I would be OK with a ground effect class for Kites.
Could a windsurfer or kitesurfer, go as fast as this craft in these conditions? If not what is the relevance of a world record or a claim for whom is the fastest? fastest dependent on what variables?
Check it:
JB this time is purely hypothetical but I have flashed down the run on a killer gust on my SP44 with a 20cm fin just in front of Slowie on his SP40 in 21cm of water. My newly WSSRC approved GPS unit shows 50.01 knots on the dial. Slowie pulls up behind me with 49.99 on his GPS.
Now the moral question. Will Slowie validate his World Record in the face of what he has just seen knowing that but for a mere technicality someone has already been there.
This scenario will happen, not with me of course as a player, but we already have an unverified 50 plus on the dial.
) but I recon the limits are somewhere around 145-150 deg off the wind with current technology. Broader than that and even the most efficient craft in the strongest sailable conditions go slower.
) but I recon the limits are somewhere around 145-150 deg off the wind with current technology. Broader than that and even the most efficient craft in the strongest sailable conditions go slower.
Great video of Hydroptere, what a boat, Hardie's right, different categories are needed - and if it was possible to define "open ocean" it would have to be the premier category?? My French is rusty but did someone on board say "quarante-cinq"?
The video conditions looked similar to what it must have been outside on the practice day before this years LOC, where mid 30s were reported by a gps-speedsurfer.
The drag associated with generating lateral resistance can also be reduced in shallow water, so for definition purposes it doesn't get around the problems being had with hull width.
