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Huge drag. Problems with cavitation = sudden change of lift.

Since speeds went above 200mph, 5 out of 7 of the guys who have attempted the unlimited WWSR have wound up dead as a result, and one of the other two suffered life-changing injuries. So you'll probably find that the number of >sane< people in the queue ahead of you is quite short.

The problem with supercavitating foils (whether deliberatley ventilated or cavitating) - given, that as you say, nearly all the lift is from the lower surface - is that you're (literally) dragging along a massive amount of turbulent sh*t behind and around them that you don't need to. If you're going to be generating nearly all the lift from the lower surface, then, hey, here's an idea: why not just have the upper surface in free air where it's much less draggy? Wow... I think I've just invented the hydroplane! 🙂 I'm guessing that the Thrust WSH team is willing to accept the drag penalty of a supercavitating foil because they think they can use it (with illegal sensors and servos...) to control the pitch of the craft. Which is all very well: a) IF it works (which is incredibly sketchy, given that all pitch authority is instantly lost if the foils emerge into free air) b) if you ignore the rulebook, and; c) If you ignore the fact that you can do the same thing with an aerodynamic stabiliser (a la Spirit of Australia), with a much lower drag penalty.

@@martinstuart3264 Yes good points. They started with using hydroplane shoes. I was responding to the video, showing T hydrofoils, with conventional foil shape. Which would be incredibly stupid in my opinion. They work fine at slow speed (up to 30 knots) but really bad for this application.

Yes, slanting foils are a good idea, perhaps as part of a hybrid in conjunction with conventional planing surfaces: with a conventional hydroplane you need vertical fins (in addition to the rudder) to maintain longitudinal control authority, so perhaps there would be scope to replace these with slanting, surface piercing and supercavitating foils that contribute to both jobs... providing some hydrodynamic lift as well as directional stability? Again, you've got to ask yourself whether there is any worthwhile drag benefit versus a conventional planing shoe + fin arrangement, though. I'd ditch the whole 'active foils' thing though: apart from simply being against the rules, its an unnecessarily complex potentially disaster-prone solution. I firmly believe that whatever design you come up with, it needs to be inherently (passively) stable. The whole thing smacks of a bunch of engineers trying to be clever for the sake of cleverness: you need to be ruthlessly pragmatic in adopting the simplest, cheapest, >lowest drag< solution that's available, even if that means your engineers don't get to play around with interesting toys.

@@martinstuart3264 Agree that they should ditch the active foils idea. It adds complexity and scope for disaster. I am guessing they have so much thrust that they are not so worried about drag. No it is not engineers, it is academics. Academics are very knowledgeable but lack the feel for the problem that engineers have. I have worked both in industry and in university. Academics are clever people but vastly over estimate their practical abilities.

@@StabilisingGlobalTemperature In fairness, Lorne Campbell is a VERY experienced and VERY well-known designer of fast powerboats - possibly THE most famous such designer left alive, now that Peter Du Cane, Don Aronow, Renato 'Sonny' Levi and Fabio Buzzi have all left the building... though of course there is a big difference between a fast offshore powerboat and a WWSR craft. The latter is more about aerodynamics, once you get up to 'working' speeds. We don't know how much of the design is Lorne's though, and how much has been imposed on him by Noble or others. I have my reservations about the use of the Spey (simply because it was readily available, it seems), too. It means that Thrust WSR will be a big beast, and therefore probably limited to running (in the UK) on Loch Ness rather than the more sheltered Coniston Water, but that's another discussion...

The UIM rules have a definition for what constitutes a 'boat' to cover this: "A boat is a vessel that floats on the water when stationary and continuously derives support, directional control or propulsive effort from hydrodynamic forces." Because they use the word 'or' (and I have checked and confirmed this with them in the past) it means that you need ONE of the three when the 'boat' is under way: support, directional control or propulsive effort. Clearly a jet or rocket engine does not deliver its propulsive effort to the water, therefore you're left with support OR directional control. Theoretically, this means that you could run a ramwing almost entirely clear of the water in surface effect, provided its directional control was still from an immersed rudder. In practice, keeping in such close surface effect that you could guarantee that at least part of the rudder always remained immersed would be incredibly difficult, if not impossible (particularly since you're not allowed sensors or computer intervention to keep it at the right height). As a slight aside, my understanding is that Lee Taylor's 'Hustler' had a jet engine and used thrust vectoring (basically, steerable titanium vanes just behind the tailpipe of the jet engine to direct its thrust) to steer, but was otherwise a relatively conventional hydroplane that derived only support from the water.

Agreed. Same problem with the water brake fitted on Bluebird K7 - it's bugger all use once the boat is airborne. They're relying on the active foils ensuring that it never >does< leave the water, but the history of very fast boats shows this to be quite an optimistic assumption. You don't even need an aerofoil to be active, if you design it right. The current record holder - Spirit of Australia - and her successor use a fixed rear stabiliser to do the job. The rear 'wing' (stabiliser) on SoA is symmetrical and at zero angle of attack at normal trim, so generates neither lift nor downforce. If the nose pitches up, it results in a positive angle of attack, so the stabiliser - acting well behind the CoG - corrects the situation (ditto with a negative angle of attack if the nose pitches down, though that's not really a problem with a conventional 3-point hydro). It's a much simpler, more elegant engineering solution than all this nonsense with computer controlled, surface-scanning, super-cavitating hydrofoils.

@@martinstuart3264 Good points. I also think it must be inherently stable aerodynamically. To avoid flipping up or down. I worry that this WSH boat looks as though it will flip up. It really must have the same sort of horizontal stabiliser that SoA had. There is a RUclipsr who has done considerable work on wing in ground effect. For it to be stable he has come up with his own aerofoil. Basically a thin wedge symmetrical. If it flys far from the surface there is equal force from upper and lower sides. Close to the water surface the lower side gives the lift. And naturally maintans a very stable constant height.

@@StabilisingGlobalTemperature I designed (and tested models of) a reverse three-pointer using the symmetrical 'wedge' aerofoil idea back in the early 1990s. The problem I ran up against was that as speeds increase, the 'neutral' surface effect height that it wants to run at (ie. the height at which the ground effect diminishes to the point that it doesn't want to 'fly' any higher, countered by the weight of the craft) is much too high to retain an immersed rudder, and as per my comment elsewhere, with a jet engine the rules require that you must either be in physical contact with the water, or else derive directional control from it. The only way you can do that with even a 'wedge' ground effect aerofoil would be to have variable control surfaces, and again you're back to needing height sensors and a computer (against the rules) to manage it, 'cos it would be well beyond the reactions of a human pilot to control accurately enough. The solution I came up with was a 'hybrid' using wedge section aerofoils in a reverse three-pointer (actually closer to a diamond-shaped 4-pointer) design as 'wings' that connected the sponsons to the main body. The wings generated >some< lift from ground effect (and stabilised the craft in pitch), but still relied on the sponsons and conventional planing surfaces to do part of the work. But we digress... Lorne Campbell's comment at 2:12 is worrying, to say the least: he's quoting a critical pitch angle of approximately 0.75 degrees, which I assume is what they've found for the Thrust WSH hull design without hydrofoils. Donald Campbell's Bluebird K7 had a critical pitch angle of over 8 degrees at its orginal design speed of 250mph, and we all know that even that didn't prove enough... a critical pitch angle of 0.75 degrees is plain suicidal. Lorne is a highly experienced and competent naval architect, but I think it's fair to say that he's no aerodynamicist and has no knowledge of working at these sorts of speeds. The project started from a quite different Reid Railton reverse three-point hull design, so I'm not sure how they've ended up where they are, but the cynic in me can't help comparing it to Art Arfon's attempt to fit Green Monster with floats for a WWSR attempt... what we appear to have here is an attempt to mount Thrust II on floats, albeit with a Spey in place of the Avon. If the wind tunnel (or CFD computer) is telling them that this is only giving a critical pitch angle of 0.75 degrees, then it's time to dig out a clean sheet of paper and head back to the drawing board.

You never know. these guys might be actual experts. it won't hurt if it doesn't help.

This is a poor attitude.

@@procatprocat9647 No. No it’s not, the people in these comments have basic knowledge of boats and attempt to lecture experts on the topic. It’s all over the internet, people with a very baseline level experience thinking that whatever is in their mind hasn’t been thought of by the experts, and usually spouting the simplistics ways we teach concepts at the start without realising that the more advanced you get, the more you realise the basic things you were taught are wrong and its more nuanced etc.

​@smokingspitfire1197 Wow. World speed challenges aren't technically difficult, well not as difficult as the marketing and funding aspects. The biggest challenge isn't anything to do with geeky stuff, it's all about the interaction with the public, to make it relevant and to gain traction in the media and get under the skin of the public. To do that, you need to engage with people and encourage them in a positive sense. It's lucky that you have no part in any project because your attitude would sink it. Edit - Look at it this way. Maybe someone in these comments will make a suggestion that solves the most fundamental issue. Or maybe their comment will trigger a thought process that helps in some way Attempting to shut down free thought in the way you are doing is foolish and destructive.

@@procatprocat9647 I would never work in PR anyway, but the people in these comments are literally telling the actual experts what to do.

They don't forbid moveable surfaces - current Unlimited Racing Hydroplanes in the United States employ driver-adjustable canards to control front-end lift, controlled by a foot pedal in the cockpit. If it's under the direct control of the on-board pilot/crew, it's fine. What is forbidden is ths use of sensors, autopilots or auto trim in the control loop, which effectively prohibits the control of moveable surfaces >by computer<. The rule specifically prohibits 'attitude or acceleration sensors' in the control loop and also specifically prohibits the use of gyros, so you couldn't even use a 'dumb' (mechanical) self-stabilising system. Edited to add: sensors >outside< of the control loop are also permissable, so, for example, it would be fine to have a hydroPLANE similar to the original design that used pitch sensors to illuminate a big yellow light in the cockpit that tells the pilot to put his foot on a pedal that operates a canard that in turn trims the nose down, if things start to get out-of-kilter. Most 'blowover' type hydroplane crashes happen remarkably slowly - if you watch the video footage after the event, it's usually obvious that things have started to get ugly several seconds before the point of no return - so such manual warnings could still be useful, if not foolproof.

It’s all to just break the water speed record

An auto pilot? Joke right?Clearly you don’t understand the complexity of controlling flight of a hydroplane that’s also a hydrofoil! at those insane speeds too of course! just the flight on foil’s alone is going to need gyroscopic and by the looks of prototype’s an ultrasonic or laser height edit= (it is sonar)sensor to provide feedback to control pitch! Unless you know of any thing capable? I don’t think so! so go find an auto pilot that is capable of flying a one off design!

What I do understand the likes of Warby.Cobb.Cambell need I go on were true pioneers of both land and water speed record attempts not including our friends in the USA A simple question a computer or a human being

​@@jamesbishop2555who makes the computer programs? Who builds the servos, foils etc? What a dumb question

No doubt that this is a human endeavour and wicked hard to do. No doubt computers need to be involved and are relevant in pretty much all speed records these days at some point. However, it seems fair to ask who is controlling the boat. Or to what level a driver needs to be in charge for it to qualify for a speed record by a human. After all, there ought to be a difference between a record breaking autonomous boat that happens to carry a human passenger and a boat that is controlled by a human. Is it enough that the human decides over direction and beginning and end of acceleration to qualify as human control? I am sure that is written down somewhere in a rule book.

@@my_dear_friend_ It certainly is written down in a rule book: the UIM rules clearly and explicitly prohibit sensors (and therefore computer control) in the control loop for any moveable surfaces. Without such a rule, you might as well replace the driver with a sack of potatos and a Raspberry Pi - there's no point in risking human life, if the human is merely ballast.

and the videos look like they are also just from 2000

In the document I found from 2021 this is 709.1, and yep it sounds like this would not be allowed. Moveable hydrofoils sound a lot like “moveable surfaces”, and IMUs incorporate accelerometers. So yes, that’s not going to happen. However this is the same folk that allowed the land speed record cars to be pushed along via the expulsion of gasses, so I doubt it’ll be a major stumbling block.

@@lawrencemanning Despite their undoubted achievements, Richard Noble and the Thrust team were NOT the same folk that brought forth thrust-propelled land speed record cars - those go back to Dr Nathan Ostich's 'Flying Caduceus' and Craig Breedlove's 'Spirit of America', back in the early 1960's. Then there was Art Arfons' Green Monster and the Blue Flame driven by Gary Gabelich, among others. Thrust 2 didn't come along until the 1980s... a latecomer, relatively speaking. If they're relying on a rule change to make the design acceptable, it would seem sensible to negotiate this with the UIM >before< getting too deep into the design of the boat, but the fact that there have been a couple of editions of the UIM rulebook since this project commenced does not suggest this to be the case. The problem for the UIM is that if they allow such a fundamental rule change for WWSR craft, they'll soon find other race classes being computer controlled, and next thing you know you're left with passenger-carrying drones lapping a circuit...

When I said “this is the same folk” I was referring to the rule makers, not Noble and co. I’ve followed the LSR on and off since I was a boy and know that the change to allow jets/rockets occurred before Noble got involved in, what, the early 80s? I only knew about Blue Flame and will find out more about the rule change as, whilst I don’t agree with it at all, it is interesting. It is a slippery slope for sure, but I imagine the rules will be changed in a way that won’t allow your doom and gloom scenario. It’ll come down to money and “marketing”. At least they won’t change that much, yet. 😢

@@lawrencemanning It's not the same rulemakers, either: the Land Speed Record is governed by the Federation Internationale de l'Automobile (FIA)... the Water Speed Record is governed by the Union Internationale Motonautique (UIM). Completely separate organisations. As an aside, the first jet Land Speed Record (Breedlove's Spirit of America) was sanctioned by the Federation Internationale de Motocyclisme (the governing body for motorcycle racing), but that was because it didn't qualify as a 'car' under FIA rules becuase it only had three wheels, not because it was thrust driven... Flying Caduceus (which had four wheels) had been sanctioned by the FIA previously, but just hadn't gone fast enough to take the record.

If a record speed is attained and verified by independent witnesses the public will accept it as a record whatever the UIM says.