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      Abbreviated rules   07/28/2017

      Underdawg did an excellent job of explaining the rules.  Here's the simplified version: Don't insinuate Pedo.  Warning and or timeout for a first offense.  PermaFlick for any subsequent offenses Don't out members.  See above for penalties.  Caveat:  if you have ever used your own real name or personal information here on the forums since, like, ever - it doesn't count and you are fair game. If you see spam posts, report it to the mods.  We do not hang out in every thread 24/7 If you see any of the above, report it to the mods by hitting the Report button in the offending post.   We do not take action for foul language, off-subject content, or abusive behavior unless it escalates to persistent stalking.  There may be times that we might warn someone or flick someone for something particularly egregious.  There is no standard, we will know it when we see it.  If you continually report things that do not fall into rules #1 or 2 above, you may very well get a timeout yourself for annoying the Mods with repeated whining.  Use your best judgement. Warnings, timeouts, suspensions and flicks are arbitrary and capricious.  Deal with it.  Welcome to anarchy.   If you are a newbie, there are unwritten rules to adhere to.  They will be explained to you soon enough.  
schakel488

New concept for the AC foiling monohull revealed.

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Just read in Yachts and Yachting
http://www.yachtsandyachting.co.uk/americas-cup/kiwis-reveal-new-full-foiling-monohull-americas-cup-class-design/
 

The wait is over! We now have confirmation of what the next America’s Cup class will look like – and foils are very much a feature. Here’s what Emirates Team New Zealand had to say in a statement issued this evening (20 November) along with some exciting first visuals…

An exciting new era in America’s Cup racing has been unveiled today as the concept for the AC75, the class of boat to be sailed in the 36th America’s Cup is released illustrating a bold and modern vision for high performance fully foiling monohull racing yachts.


AC_75_2422-696x392.jpg.94163ebd63a11fc551194872def2c126.jpg

AC_75_0949-696x392.jpg.747fedc18555c6b316e400252995601b.jpg
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The Emirates Team New Zealand and Luna Rossa design teams have spent the last four months evaluating a wide range of monohull concepts. Their goals have been to design a class that will be  challenging and demanding to sail, rewarding the top level of skill for the crews; this concept could become the future of racing and even cruising monohulls beyond the America’s Cup.

The AC75 combines extremely high-performance sailing and great match racing with the safety of a boat that can right itself in the event of a capsize. The ground-breaking concept is achieved through the use of twin canting T-foils, ballasted to provide righting-moment when sailing, and roll stability at low speed.

The normal sailing mode sees the leeward foil lowered to provide lift and enable foiling, with the windward foil raised out of the water to maximise the lever-arm of the ballast and reduce drag. In pre-starts and through manoeuvres, both foils can be lowered to provide extra lift and roll control, also useful in rougher sea conditions and providing a wider window for racing.

AC_75_1259-696x392.jpg.899a3897bf22ba3b2c944a31b14daeb3.jpg

An underlying principle has been to provide affordable and sustainable technology ‘trickle down’ to other sailing classes and yachts. Whilst recent America’s Cup multihulls have benefitted from the power and control of rigid wing sails, there has been no transfer of this technology to the rigs of other sailing classes. In tandem with the innovations of the foiling system, Emirates Team New Zealand and Luna Rossa are investigating a number of possible innovations for the AC75’s rig, with the requirement that the rig need not be craned in and out each day. This research work is ongoing as different concepts are evaluated, and details will be released with the AC75 Class Rule  before March 31st, 2018.

The America’s Cup is a match race and creating a class that will provide challenging match racing has been the goal from the start. The AC75 will foil-tack and foil-gybe with only small manoeuvring losses, and given the speed and the ease at which the boats can turn the classic pre-starts of the America’s Cup are set to make an exciting comeback.  Sail handling will also become important, with cross-overs to code zero sails in light wind conditions.

A huge number of ideas have been considered in the quest to define a class that will be extremely exciting to sail and provide great match racing, but the final decision was an easy one: the concept being announced was a clear winner, and both teams are eager to be introducing the AC75 for the 36th America’s Cup in 2021.

The AC75 class rule will be published by March 31st 2018.

More reaction on this announcement coming soon…

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Although racing performance has been the cornerstone of the design, consideration has had to be focused on the more practical aspects of the boat in the shed and at the dock, where both foils are canted right under the hull in order to provide natural roll stability and to allow the yacht to fit into a standard marina berth.
AC_75_1731-696x392.jpg.a751244fc7e11b6320b18a3759aac699.jpg
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AC_75_3336-696x392.jpg.dc5140d0d7b83f75021660c84c94c6f3.jpg
I like this concept very much.
Competetive, spectaculair, fast and beautiful.

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^ If you squint hard....

 

Try this

clik

23847471_10213280481582509_2031990740074

Tips add nothing but drag.../foil expert mode

 

'Flying filler'?!

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What a joke!  I though everyone wanted to go back to traditional monohull racing with the real yachtsman on the crew instead of gerbils?  All they did was replace the platform that the sailors stand on and give it foils that will require the boats to keep farther apart.  Those foils look like weapons that can be used to clear the opponents crew off the deck or cut off the opponents foils under water.  This is a way more complex design than the AC50's, they could have use stabilized the foiling of the AC50's and would have been a much better design.  So how will they power the movement of these foils?

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Did Bernasconi read one of my previous post ? :)

“Although the boats will be foiling most of the time it is going to be incredibly important to have a hull which gets you foiling as quickly as possible”, Bernasconi says. “That's an interesting design problem. That is going to be a big part of the design focus - how do you design a hull that gets you accelerating well and then gets you up on to the foils before your competition?”

The AC75 has just three tonnes of total ballast, spread across two swivelling foils and 1000kg of crew weight. The trade-off is likely to have sufficient beam to achieve maximum righting moment and get foiling as soon as possible. The other side of the beam trade-off is to have a boat that is narrow to reduce drag as much as possible and lift the speed that way. That’s a design conundrum that can only be sorted out in the simulator – provided it is accurately calibrated for the real world."

 

I think the design choice will be based on the final rule. In order to foil early you need a light boat and power +RM. The RM will be depending of the possible power of the sails and the rule.

Anyway, speed is more important than power to fly early, so my prediction is that we will have tulip hulls like the 505, narrow at the bottom, wide on the top for RM. Nothing to do with the design we see now.

But i don't know the wind conditions at the time it will be sailed in Auckland, wether they will advantage early flying or max power and speed.

And ............if it will be Aukland !

 

 

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'I think the sailing angles will be similar to those we saw in the AC50. You start off lower at the low-speed wind range and get up to between 40-50degrees higher up the windspeed range - depending on sailing modes and how you chose to sail the boat. It is early days with the AC75 concept, and we haven't got the answers yet.”.
 

I don't think they will be similar, the boat is heavier, there is no wing. The should go slower deeper downwind, and slower higher upwind.

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59 minutes ago, Tornado-Cat said:

Did Bernasconi read one of my previous post ? :)

“Although the boats will be foiling most of the time it is going to be incredibly important to have a hull which gets you foiling as quickly as possible”, Bernasconi says. “That's an interesting design problem. That is going to be a big part of the design focus - how do you design a hull that gets you accelerating well and then gets you up on to the foils before your competition?”

The AC75 has just three tonnes of total ballast, spread across two swivelling foils and 1000kg of crew weight. The trade-off is likely to have sufficient beam to achieve maximum righting moment and get foiling as soon as possible. The other side of the beam trade-off is to have a boat that is narrow to reduce drag as much as possible and lift the speed that way. That’s a design conundrum that can only be sorted out in the simulator – provided it is accurately calibrated for the real world."

 

I think the design choice will be based on the final rule. In order to foil early you need a light boat and power +RM. The RM will be depending of the possible power of the sails and the rule.

Anyway, speed is more important than power to fly early, so my prediction is that we will have tulip hulls like the 505, narrow at the bottom, wide on the top for RM. Nothing to do with the design we see now.

But i don't know the wind conditions at the time it will be sailed in Auckland, wether they will advantage early flying or max power and speed.

And ............if it will be Aukland !

 

 

Could be. I'm really interested in how much design latitude the final rule will give-I'm guessing quite a lot. The real NZAC could be quite different in some respects to the renders we've seen so far.

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1 hour ago, Doug Lord said:

Could be. I'm really interested in how much design latitude the final rule will give-I'm guessing quite a lot. The real NZAC could be quite different in some respects to the renders we've seen so far.

@Sailbydate Told you so!

I normally love being right, this time - not so much!

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2 minutes ago, jaysper said:

@Sailbydate Told you so!

I normally love being right, this time - not so much!

Fuck. I should have run for the hills while I had the chance. ;)

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Without the rules who really knows, but why bother with a hull at all? All you need is a centerline to attach the foils too, after than everything else is just aerodrag. If the rules spec a max length of the foils then it will be necessary, if they spec a maximum span of the boat I can't see any reason not to have a 1' wide hull with very long foils. You could use an AC72 hull (just one) with very long foil spans. 

The more I think about this rule the less I like it. It is going to be so twisted by the design rules there will be nothing meaningful developed here. 

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11 minutes ago, StumbleNola said:

Without the rules who really knows, but why bother with a hull at all? All you need is a centerline to attach the foils too, after than everything else is just aerodrag. If the rules spec a max length of the foils then it will be necessary, if they spec a maximum span of the boat I can't see any reason not to have a 1' wide hull with very long foils. You could use an AC72 hull (just one) with very long foil spans. 

The more I think about this rule the less I like it. It is going to be so twisted by the design rules there will be nothing meaningful developed here. 

So where are the crew supposed to be positioned without a hull?

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4 minutes ago, sclarke said:

So where are the crew supposed to be positioned without a hull?

Set of nets on outrigger style set up?

Not saying it will happen, just saying that is a way to achieve it.

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  ^^^ Nah. The video has been produced to satisfy Bertelli's craving for a monohull. But when boats are built you'll see the logical setup: a foiling tri without amas - more or less what you say

 

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11 minutes ago, Xlot said:

 

  ^^^ Nah. The video has been produced to satisfy Bertelli's craving for a monohull. But when boats are built you'll see the logical setup: a foiling tri without amas - more or less what you say

 

Yep, calling these things monos is a little bit like calling Caitlin a woman.

Sure, technically it might be true but nobody seems to be that impressed with its "appendages" :D

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7 minutes ago, jaysper said:

Yep, calling these things monos is a little bit like calling Caitlin a woman.

Sure, technically it might be true but nobody seems to be that impressed with its "appendages" :D

Not even sure if technically it is true.  Is it buoyancy or lift that makes a multi-hull a multi-hull?  Focusing on the physics, it is basically the same.... it's a multi.

I wish we had a test like that for a witch to identify it as a mono or multi..... unfortunately, both float.

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Just now, GauchoGreg said:

Not even sure if technically it is true.  Is it buoyancy or lift that makes a multi-hull a multi-hull?  Focusing on the physics, it is basically the same.... it's a multi.

I wish we had a test like that for a witch to identify it as a mono or multi..... unfortunately, both float.

For all intents and purposes, I can't see any substantial functional difference between the AC75 and the AC50.

If we assume they foil for 100% of the time, then what does the hull offer differently other than the fact that re-positioning the crew will not do as much to change the righting moment of the boat?

The type of foil is dramatically different and this may make the performance characteristics COMPLETELY different from the 50s, but fucked if I have the skill set to look at them at predict what those differences might be.

I am hoping like crazy that these things don't have the same issues (from my PoV) as the 50s, which is shit to match race and manoeuvres too costly. But, I can't see anything to suggest that those hopes will come to fruition.

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1 minute ago, GauchoGreg said:

Not even sure if technically it is true.  Is it buoyancy or lift that makes a multi-hull a multi-hull?  Focusing on the physics, it is basically the same.... it's a multi.

I wish we had a test like that for a witch to identify it as a mono or multi..... unfortunately, both float.

Don't you think you're over thinking that a little? Surely Multiple hulls (multi for short) meaning more than one, would constitute a "Multi" hull. Mono (one, or single) is what should constitute a "mono" hull. If multiple appendages constitutes a multihull, that would surely make Wild Oats XI a multi hull, as she has (or had) more appendages than most multi hulls.

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3 minutes ago, sclarke said:

Don't you think you're over thinking that a little? Surely Multiple hulls (multi for short) meaning more than one, would constitute a "Multi" hull. Mono (one, or single) is what should constitute a "mono" hull. If multiple appendages constitutes a multihull, that would surely make Wild Oats XI a multi hull, as she has (or had) more appendages than most multi hulls.

Difference is that Wild Oats doesn't ride along ONLY on those appendages.

Other than under exceptional circumstances, the AC50s two hulls were irrelevant and if they had specified the central hull to be just a little bit lower, it could have been called a tri-maran, despite only the two foils and two rudders ever touching the water.

The AC75ws could be the same deal where there are only ever 3 points of contact with the water and none of those are the hull. Therefore, the fact that it has one object that most people identify as a hull is basically irrelevant.

Hence my joke about Caitlin, because the AC75 looks to be a multihull that "identifies as" a monohull.

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25 minutes ago, sclarke said:

Don't you think you're over thinking that a little? Surely Multiple hulls (multi for short) meaning more than one, would constitute a "Multi" hull. Mono (one, or single) is what should constitute a "mono" hull. If multiple appendages constitutes a multihull, that would surely make Wild Oats XI a multi hull, as she has (or had) more appendages than most multi hulls.

No, I think you are under-thinking this. 

This boat will be nothing like a MONO-hull, where one point of contact represents the lift/buoyancy.  And it will be nothing like Wild Oats, the IMOCAs, etc., which are all set with the hull and foil in the water together nearly all of the time (except for exceptional moments of extreme lift (such as going off the crest of a wave while at high speed), but they do NOT foil (meaning the hull and foil are in contact with the water, together) at nearly all times, and there is no such thing as stable foiling.  By the way, when the Imocas do lift off, the point of lift is still a single point and not that far off of the central hull due to the degree of heel.... check out how that leeward lifting foil is nearly straight below the hull of the boat due to the amount of heel on the boat at those periods where the boat is momentarily lifting off.

Think deeper, yourself, and you might just recognized that instead, the AC72 will have lift points completely separate from the central hull, far wide providing the same kind of multi-lift points and righting moment consistent with the theory behind multi-hulls, and the entire boat will be held up by those separate lift points most of the time.  As Tornado Cat points out, this is a bad multi-hull concept since they are intentionally adding a crapload of weight in order to satisfy the Prada-Boss desire to see the boat look like a monohull part of the time.

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If you went with the giant moth idea where the wings are big enough for the crew to generate significant changes in righting moment, it might lead to a lot of entertaining running back and forth and falling over (boat and crew). 

In reality I too am seeing this evolve towards the foiling trimaran concept unless they force the hinged foil design, but we all agree this seems just ludicrously dangerous.

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Has anyone done calculations on the giant moth idea? I wonder if you could balance some degree of foiling stability with perhaps two J-foils submerged full time so that the leward one generates progressive righting moment, but you still have big wings for 2000lbs of crew to run around on. What is the bandwidth of 10 crew members acting as a stabilizing force generator on 6 meter wings anyway? (i.e. how fast can they collectively react relative to typical force inputs from the wind and sea?) Someone fire up Simulink. Where are you Mr Schickler? 

 

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Since the concept in the simulation is a MonINO (Monohull in Name Only (TM)), I think, in the end, they will decide to add amas for RM and eliminate ballast and complication. This will be a safer design, will provide a definite change from AC35, and will be a face-saving device since, by squinting, LR will see a monohull. Win-win-win.

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54 minutes ago, Foiling Optimist said:

Has anyone done calculations on the giant moth idea? I wonder if you could balance some degree of foiling stability with perhaps two J-foils submerged full time so that the leward one generates progressive righting moment, but you still have big wings for 2000lbs of crew to run around on. What is the bandwidth of 10 crew members acting as a stabilizing force generator on 6 meter wings anyway? (i.e. how fast can they collectively react relative to typical force inputs from the wind and sea?) Someone fire up Simulink. Where are you Mr Schickler? 

 

Here:  https://www.boatdesign.net/threads/60-or-20-ocean-racing-monofoiler-design-discussion.15143/

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1 hour ago, sclarke said:

Don't you think you're over thinking that a little? Surely Multiple hulls (multi for short) meaning more than one, would constitute a "Multi" hull. Mono (one, or single) is what should constitute a "mono" hull. If multiple appendages constitutes a multihull, that would surely make Wild Oats XI a multi hull, as she has (or had) more appendages than most multi hulls.

A valid point, the lines are getting a little blurred on that basis. 

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America’s Cup: Affordability in question

Published on November 26th, 2017 

The big reveal of the AC75 to be sailed in the 36th America’s Cup has tongues dragging. What was expected was a mononull, not a transformer. The boat looks like it was designed by committee…working off input from a focus group. 

So much for making the boat relatable.

http://www.sailingscuttlebutt.com/2017/11/26/americas-cup-affordability-question/

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26 minutes ago, ~Stingray~ said:

America’s Cup: Affordability in question

Published on November 26th, 2017 

The big reveal of the AC75 to be sailed in the 36th America’s Cup has tongues dragging. What was expected was a mononull, not a transformer. The boat looks like it was designed by committee…working off input from a focus group. 

So much for making the boat relatable.

http://www.sailingscuttlebutt.com/2017/11/26/americas-cup-affordability-question/

I don't think it was designed by committee. 

I think it was designed to be as fast as possible whilst technically still delivering on the promise of a mono.

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Dennis is right about a few things I think. It's going to be expensive developing this iteration of the cup boat. The ballasted foils present a massive engineering challenge that will be anything but cheap to develop. All teams will need  bleeding edge simulation software - most likely developed in-house, again not cheap. ETNZ/Prada definitely have an advantage here. If you haven't started writing your code now, or have extensive existing code you're not going to be in this.

Time frame is looking really tight - ridiculously tight. You have to be building by the end of next year, so the design has to be sorted in less than 12 months? Hard to see this being achievable with the design challenges of the concept. Dennis is right when he says there won't be many challengers, and that ETNZ doesn't care. ETNZ want to drag out their cup occupation, so they may be thinking more about a bigger event in AC37, as at this stage, to me, ETNZ/Prada are going to struggle to make the start time on time for AC36 - no one else is going to come any where close to making it - including Ben/NYYC.

So my prediction this far out is, that unless a 12month delay is implemented, AC36 will be between ETNZ and Prada, but no one else.

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I'll put a buck the boat will NOT BE BUILDABLE

The more I look at it, and imagine how they are going to design this, build it, and race it - the pieces don't come together at all. 

I expect the foils will be drastically scaled down to imoca 60 size. so the boats won't be foilers, unless they get very flat water and wings. 

I still believe that VOR, AC and Vendee all need to be managed together. 

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4 hours ago, GauchoGreg said:

No, I think you are under-thinking this. 

This boat will be nothing like a MONO-hull, where one point of contact represents the lift/buoyancy.  And it will be nothing like Wild Oats, the IMOCAs, etc., which are all set with the hull and foil in the water together nearly all of the time (except for exceptional moments of extreme lift (such as going off the crest of a wave while at high speed), but they do NOT foil (meaning the hull and foil are in contact with the water, together) at nearly all times, and there is no such thing as stable foiling.  By the way, when the Imocas do lift off, the point of lift is still a single point and not that far off of the central hull due to the degree of heel.... check out how that leeward lifting foil is nearly straight below the hull of the boat due to the amount of heel on the boat at those periods where the boat is momentarily lifting off.

Think deeper, yourself, and you might just recognized that instead, the AC72 will have lift points completely separate from the central hull, far wide providing the same kind of multi-lift points and righting moment consistent with the theory behind multi-hulls, and the entire boat will be held up by those separate lift points most of the time.  As Tornado Cat points out, this is a bad multi-hull concept since they are intentionally adding a crapload of weight in order to satisfy the Prada-Boss desire to see the boat look like a monohull part of the time.

hull1

hʌl/

noun

1.

the main body of a ship or other vessel, including the bottom, sides, and deck but NOT the masts, superstructure, rigging, engines, and other fittings.

synonyms:framework, body, frame, skeleton, shell, structure, basic structure; 

exterior

"the wooden hull of the ship"

It has nothing to do with lifting surfaces or timing of surfaces touching the water together, so no, I'm not underthinking it.

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4 hours ago, ~Stingray~ said:

I wonder if we will see crew hiking to windward at times? That hull is wide.

Interesting you make that observation. I don't think she's all that wide at all - although I don't recall a max-beam for the box-Rule being declared at this stage. Looking at the rendered images (and assuming that's a close representation of here design lines) I'd say her length of 75' is a little more than 3 x her max-beam. That is NOT especially wide.

Am I missing something?

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2 minutes ago, sclarke said:

hull1

hʌl/

noun

1.

the main body of a ship or other vessel, including the bottom, sides, and deck but NOT the masts, superstructure, rigging, engines, and other fittings.

synonyms:framework, body, frame, skeleton, shell, structure, basic structure; 

exterior

"the wooden hull of the ship"

Way to think deeply. 

 

As we have been saying the AC72 is MINO, which is obvious to all who think objectively, rather than think in the way of My-Team-Is-Faultless, and I will just take what is told to me. 

The premise of a multi-hull is to have multiple points of lift, with those points set to the side to maximize RM, while a monohull has always utilized a big heavy, deep keel to provide RM to a singular hull.  While these boats will have a central hull and something(s) vaguely resembling keel(s) that can be deployed as such, the hope is that the foils will never be deployed as such in actual sailing conditions, and instead, they will be deployed as outward points of lift, exactly like amas on a tri, and THE HULL will be doing none of the actual work of what a hull would typically do in the case of a monohull.

So, when you claim "Don't you think you're over thinking that a little", and make a completely incorrect analogy to Wild Oats, you are showing your total lack of objectivity.

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5 minutes ago, GauchoGreg said:

Way to think deeply. 

 

As we have been saying the AC72 is MINO, which is obvious to all who think objectively, rather than think in the way of My-Team-Is-Faultless, and I will just take what is told to me. 

The premise of a multi-hull is to have multiple points of lift, with those points set to the side to maximize RM, while a monohull has always utilized a big heavy, deep keel to provide RM to a singular hull.  While these boats will have a central hull and something(s) vaguely resembling keel(s) that can be deployed as such, the hope is that the foils will never be deployed as such in actual sailing conditions, and instead, they will be deployed as outward points of lift, exactly like amas on a tri, and THE HULL will be doing none of the actual work of what a hull would typically do in the case of a monohull.

So, when you clatim "Don't you think you're over thinking that a little", and make a completely incorrect analogy to Wild Oats, you are showing your total lack of objectivity.

The only obvious thing is the definition of monohull and mutihull that you will find in the Oxford dictionary. Obvious to those who think objectively instead of thinking something can be anything they want it to be, instead of what it actually is. I guess you're a flat Earther too? it really is very simple. Oxford dictionary, first look up the definition of Hull, then look up multihull, and Monohull, and the truth will set you free.

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Just now, sclarke said:

The only obvious thing is the definition of monohull and mutihull that you will find in the Oxford dictionary. Obvious to those who think objectively instead of thinking something can be anything they want it to be, instead of what it actually is. I guess you're a flat Earther too? it really is very simple. Oxford dictionary, first look up the definition of Hull, then look up multihull, and Monohull, and the truth will set you free.

Too funny.  Enjoy your America's cup going back to traditional monohulls.

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Just now, GauchoGreg said:

Too funny.  Enjoy your America's cup going back to traditional monohulls.

Thanks enjoy watching those Catamarans or Tri-marans, or whatever you'd like them to be.

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13 minutes ago, sclarke said:

Thanks enjoy watching those Catamarans or Tri-marans, or whatever you'd like them to be.

I would prefer everyone to be honest in their objectives and the principles of the boats to be used, rather than having a boat that is supposed to be traditional in design/fundamentals, more relatable, more affordable, safer, equal in performance, etc., when it is none-of-the-above.  But hey, it looks like a monohull and the Prada-Boss gets what he paid for (if he squints just right).

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20 minutes ago, sclarke said:

The only obvious thing is the definition of monohull and mutihull that you will find in the Oxford dictionary.

And why do you spend time and effort to define a mono or find it in the Oxford dictionary, only PB and GD can decide the definition, they could even decide to organize the venue where the earth is flat.

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7 minutes ago, GauchoGreg said:

I would prefer everyone to be honest in their objectives and the principles of the boats to be used, rather than having a boat that is supposed to be traditional in design/fundamentals, more relatable, more affordable, safer, equal in performance, etc., when is it none-of-the-above.  But hey, it looks like a monohull and the Prada-Boss gets what he paid for (if he squints just right).

"I would prefer everyone to be honest in their objectives and the principles of the boats to be used" ETNZ have always said they were going back to a monohull,  while retaining some good aspects that came out of Bermuda, and they did. True to their principles. Dan Bernasconi has said the new boats will incorporate many traditional and fundamental aspects of AC boats, hoisting sails, coffee grinders turning winches etc. It remains to be seen whether the other aspects prove to be correct. Teams will always spend what they want to spend to win the thing, so cost reduction is irrelevant, because costs have been, are, and always will be astronomical. Anyone who thinks the AC50's and the Bermuda campaigns weren't unbelievably high is kidding themselves. The Deed states the challenger dictates the boats to be raced, so they can do what they want. They wanted a boat with one hull. They got a boat with one hull. Im sorry if you thought they were bringing back the J-Class or something.

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7 minutes ago, Tornado-Cat said:

And why do you spend time and effort to define a mono or find it in the Oxford dictionary, only PB and GD can decide the definition, they could even decide to organize the venue where the earth is flat.

...And then you woke up

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7 hours ago, sclarke said:

So where are the crew supposed to be positioned without a hull?

Inside the hull. Even the RM generated by the foils, the RM of the crew is negligible. This thing will sail just like a trimaran, the leeward ama (er foil) will counteract the heeling motion and lift the hull, and the windward ama (er foil) will pull down thanks to gravity. The center hull just needs enough structural strength to prevent wracking and hold the mess of it together. 

 

This of course assumes that the operative dimensions are the total width of the boat. If the rules instead specify the maximum length of the individual foils then I would expect to see projections out from the mast. Say the inboard side of a folding ama arm from a Corsair, just fixed in place. 

 

Basically this thin operationaly can be thought of like a goofy trimaran that replaced its floats with foils. 

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Why do people assume that the AC75 will be foiling 100% of the time .. The AC50's were unable to foil 100% except in ideal conditions and their lift off wind speed was about 6 or 7 knots.

ETNZ have said that the AC75 will need 9 knots to foil and guess what .. there is less than 9 knots of wind in the Hauraki Gulf for a significant amount of time just as the wind exceeds 20 knots for a significant amount of time.

The low wind foiling speed will be a critical element of the design and that means that the AC75 will need a well designed hull that can achieve hull speed in the minimum wind that they can hold the races in.

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37 minutes ago, Terry Hollis said:

Why do people assume that the AC75 will be foiling 100% of the time .. The AC50's were unable to foil 100% except in ideal conditions and their lift off wind speed was about 6 or 7 knots.

ETNZ have said that the AC75 will need 9 knots to foil and guess what .. there is less than 9 knots of wind in the Hauraki Gulf for a significant amount of time just as the wind exceeds 20 knots for a significant amount of time.

The low wind foiling speed will be a critical element of the design and that means that the AC75 will need a well designed hull that can achieve hull speed in the minimum wind that they can hold the races in.

Yep, I must confess I have been glossing over that myself Terry.

However it still makes it a semi tri maran in my books.

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3 hours ago, ipexnet said:

I'll put a buck the boat will NOT BE BUILDABLE

I think this statement is just silly.

If you'd said that it might (or won't) perform as it has been envisaged then perhaps but then I'm not sure etnz have articulated to the rest of us precisely how this boat will perform. 

A safer bet would be to say that the technical minutiae of this boat is going to be so complex as to make the difference between the best and worst teams enormous. THAT is where I'm putting my money.

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^^ Boats that spend most of their time on foils fit neither category in their original sense.

Time for a third gender maybe?

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5 minutes ago, nav said:

^^ Boats that spend most of their time on foils fit neither category in their original sense.

Time for a third gender maybe?

Hence the Caitlin joke.

Calling these things monos just seems bizarre to me.

I get that technically they are but they have more in common with a multi IMO.

I think this was ETNZs way of keeping it's promise to go mono but actually have multi performance characteristics. 

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Form vs function. Design vs Engineering.

If the emperor and the monoheads think it's cloathed sufficiently to look like a monohull what else matters?

 

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I am hoping like crazy that these things don't have the same issues (from my PoV) as the 50s, which is shit to match race and manoeuvres too costly. But, I can't see anything to suggest that those hopes will come to fruition.

Not sure what event you were watching ? The only costly manoeuvres i saw was NZ's bear away - cart wheel and Oracle stuck behind the start line waiting  on oil pressure after some jostling with NZ .

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^ :) yup agreed

pure confirmation bias there...

Not to worry - these things will have a completely new set of issues to get exercised over!

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8 hours ago, Terry Hollis said:

Why do people assume that the AC75 will be foiling 100% of the time .. The AC50's were unable to foil 100% except in ideal conditions and their lift off wind speed was about 6 or 7 knots.

ETNZ have said that the AC75 will need 9 knots to foil and guess what .. there is less than 9 knots of wind in the Hauraki Gulf for a significant amount of time just as the wind exceeds 20 knots for a significant amount of time.

The low wind foiling speed will be a critical element of the design and that means that the AC75 will need a well designed hull that can achieve hull speed in the minimum wind that they can hold the races in.

More critical than the hull are the foils to achieve low wind speed flight, and then the tradeoff there with top end speeds.  The Q-foils we developed are all biased towards the low end so we can fly the Q23 for example in less than 5kn TWS, but then top end is pretty much limited by soft sails and other factors to the mid 20s, and a bit above if you're feeling brave!.   Mind you, we don't have or need any control systems and the Tee's will certainly need to have something.

However, say the lower TWS race limit is going to be 5knots, then you really will have to figure the tradeoffs across a likely wind spectrum over the race period so it will be interesting to see exactly what the rule box will encompass - variable foil geometry as well as rudder trim control?  

It's what the rules don't say that is always the fun thing to figure out!

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7 hours ago, Tornado-Cat said:

GD and BT said it is a mono, it's a mono

200.gif

Let me guess - That's a new AC75 short tacking...

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2 hours ago, Tornado-Cat said:

I think that basiliscus had an early premonition when he chose his id

Lol. Great point, this boat is evolutionary - Darwin would be  impressed.

https://en.m.wikipedia.org/wiki/Basiliscus_(genus)

The basilisk sometimes runs as a biped. Basilisks have the unique ability to "run" on water and, because of this, they have been dubbed as "The Jesus Christ lizard"

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43 minutes ago, ~Stingray~ said:

Lol. Great point, this boat is evolutionary - Darwin would be  impressed.

https://en.m.wikipedia.org/wiki/Basiliscus_(genus)

The basilisk sometimes runs as a biped. Basilisks have the unique ability to "run" on water and, because of this, they have been dubbed as "The Jesus Christ lizard"

He obviously was thinking about foiling, but he had to be the oracle of delphi to have the premonition that the front view of the AC75 would like a basiliscus running on water :unsure:

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3 hours ago, ~Stingray~ said:

Dang, even the rudder has surface control issues!

Final definitive proof of evolution.

Trying to run in Flippers and Goggles, would look almost exactly like that..

200.gif

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14 hours ago, hughw said:

More critical than the hull are the foils to achieve low wind speed flight, and then the tradeoff there with top end speeds.  The Q-foils we developed are all biased towards the low end so we can fly the Q23 for example in less than 5kn TWS, but then top end is pretty much limited by soft sails and other factors to the mid 20s, and a bit above if you're feeling brave!.   Mind you, we don't have or need any control systems and the Tee's will certainly need to have something.

However, say the lower TWS race limit is going to be 5knots, then you really will have to figure the tradeoffs across a likely wind spectrum over the race period so it will be interesting to see exactly what the rule box will encompass - variable foil geometry as well as rudder trim control?  

It's what the rules don't say that is always the fun thing to figure out!

While the work you have done is very impressive, boats that small are helped a lot by the live crew weight.  Even the AC50 as a catamaran with narrow hulls can easily achieve foiling speed long before RM becomes an issue.

A 75 foot mono will be required to achieve foiling speed while RM is limited so there is unlikely to be much "tradeoff" with the foils .. they will be designed for maximum lift at the lowest speed and too bad about the top speed.  Maybe the rules will allow light air and heavy air foils but they will still need to get to foiling speed within the available righting moment.

The additional complication is that they also want to fit 1.5 tons of ballast in the foils so this might make them thicker than would otherwise be desirable as well.

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21 hours ago, Justaquickone said:

I am hoping like crazy that these things don't have the same issues (from my PoV) as the 50s, which is shit to match race and manoeuvres too costly. But, I can't see anything to suggest that those hopes will come to fruition.

Not sure what event you were watching ? The only costly manoeuvres i saw was NZ's bear away - cart wheel and Oracle stuck behind the start line waiting  on oil pressure after some jostling with NZ .

They are going to be even worse. The giant foil sticking out horizontally 30' from centerline is going to make close in sailing impossible, and the loss from slowing down to mess around is going to be even worse with more wetted surface, and more weight. My guess is that touching down will hurt at least twice as much on these as in the 50's making staying out of the water even more critical. Best case is a luffing duel right at the start, but I think we could see the re-emergence of the Vanderbuilt start. Because nothing will matter as much as being out of the water at the start.

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Control of the jump off point. Just like the AC72 and AC50 only with a windward line likely more of a penalty for not being the lead boat.

The orientation of the line really didn't make that much difference, one boat getting an early entry did. And that was introduced on safety grounds.

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It doesn't matter if you are Archimedian at the start if you can force the other boat off foils too and make them slower to accelerate. But maybe the "diamond" makes that harder to achieve.

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32 minutes ago, rgeek said:

The orientation of the line really didn't make that much difference, one boat getting an early entry did.

Did it? I don't recall the first boat into the box consistently winning starts.

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6 hours ago, Terry Hollis said:

While the work you have done is very impressive, boats that small are helped a lot by the live crew weight.  Even the AC50 as a catamaran with narrow hulls can easily achieve foiling speed long before RM becomes an issue.

A 75 foot mono will be required to achieve foiling speed while RM is limited so there is unlikely to be much "tradeoff" with the foils .. they will be designed for maximum lift at the lowest speed and too bad about the top speed.  Maybe the rules will allow light air and heavy air foils but they will still need to get to foiling speed within the available righting moment.

The additional complication is that they also want to fit 1.5 tons of ballast in the foils so this might make them thicker than would otherwise be desirable as well.

What you are looking for is a balance between RM and lift, so RM is building up as lift, and of course drag. Look at Q23 vids and in the light conditions then you'll see at least one crew to leeward, so crew weight is pretty central or even biased to the leeward side to immerse the foil.  AC provisionals are very much the same geometry config as that, but that is all related to sail plan/height and then total displacement weight/arm providing the RM from the CG/ foil distance at takeoff.  And getting to that takeoff speed at which the foil can be utilised is an interesting problem in its own right.

The TNZ lot will have gone around exactly the same loops to get to what they have proposed - I do think they have missed one significant factor at this stage but that might well be figured out by the time the rule itself is released.   Be interesting to see and then dig into the wording to see what the rule really is saying - and what it is not saying....

Being AC I'm sure they will be trying to load the dice in their favour with rule omissions so they have the time advantage - and very significant that is too - to make use of the open areas to their advantage.  Every winner has done that, and sometimes that can backfire too!

 

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2 hours ago, dogwatch said:

It doesn't matter if you are Archimedian at the start if you can force the other boat off foils too and make them slower to accelerate. But maybe the "diamond" makes that harder to achieve.

Still waiting to find out how big this exclusion diamond is going to be?

I will find it extremely disappointing if luffing duels happen at a range of 20 to 30 metres apart.

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3 hours ago, rgeek said:

 

The orientation of the line really didn't make that much difference, one boat getting an early entry did. And that was introduced on safety grounds.

The orientation of the line just modified the strategy, and some strategies fitted better to some fast boats, remember Artemis.

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48 minutes ago, Justaquickone said:

Still waiting to find out how big this exclusion diamond is going to be?

I will find it extremely disappointing if luffing duels happen at a range of 20 to 30 metres apart.

And why do you think luffing duels will happen, mainly if the diamond is big enough to prevent a boat from covering the other one ? Fantasy of another century ?

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2 minutes ago, Tornado-Cat said:

And why do you think luffing duels will happen, mainly if the diamond is big enough to prevent a boat from covering the other one ? Fantasy of another century ?

Getting a hook maybe? There's usually a favoured end to fight for at the start.

The main point being that peoples expectations of the new  monohulls returning us to the glory days of close boat on boat encounters is not going to happen.

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The AC50's had a 'shape' around them as well - for umpiring purposes.

From the tip of the sprit to the bow of each hull and straight across the sterns. In theory it was possible to intrude into parts of that 'shape' without causing any actual physical interference, but the 'shape' in conjunction with the rule made it the same penalty-wise as if you had touched.

I make a WAG that the same will apply this time, with the 'shape' being  roughly a diamond, big enough to include foils fully extended on both sides - regardless of their actual cant at any given time.

As