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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.  

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I had a go at making a rough idea of how scowish you can get within the limits.

Bear in mind its been a long time since I tried to make a boatish shape, simple elliptical cross-section & bow profile (not properly tangented -_-)

M4jkQDj.png

IIQCKxe.png

Blunt but proportionally kept relatively narrow by the bow max beams.

I don't think you can really call that a scow bow, probably conventional bow more the go.

 

Interesting that rather than min/max freeboard there is a 70m^3 min volume, I've got 1150mm canoe body to (dead flat) sheer which gives this 74m^3 volume (flat deck/stern & no cockpit) so in the right ballpark.

Also no min LWL so you can do some interesting stuff with bow profiles.

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Aren't there 3 points (screws) located at the waterplane ? : two at the transom located 2 metres either side of centreline and one forward, similarly on the waterplane at 20.7 m. ~ these points have to be 25 mm + / - of waterplane when boat is afloat.

The forward point (screw) somewhat forces a vertical stem bow in the forward waterplane region, don't think a reverse bow is possible given the rule with respect perimeter and geometry control (of perimeter) the way I read the rule. 

Dont quite get the rule about the boat being between 20.6 and 20.7 metres given the screw locations ~ by my quick reading of rule.

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23 hours ago, nav said:
On 2018-04-11 at 8:48 AM, Lakrass said:

 It's not that fun to see 1km+ lead and it can quickly happen with this kind of boats.

Yeah I've watched all the races these boats have done as well - and you are so right

Maybe I didn't express myself correctly but what I mean is that gaps will grow very very quickly if you have one boat sailing upwind at ~35 knts and the other going for a reach at ~10 knts because they stop flying. Did any designer speak about the expected acceleration of those boats compared to AC50? This would be a very interesting parameter as the lower the acceleration, the bigger the gap in case a boat stop flying and the other not.

 

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3 hours ago, Ginko said:

Aren't there 3 points (screws) located at the waterplane ? : two at the transom located 2 metres either side of centreline and one forward, similarly on the waterplane at 20.7 m. ~ these points have to be 25 mm + / - of waterplane when boat is afloat.

Yes I'd forgotten that.

But also

Quote

3.8 Three screws shall be installed on the hull surface for the purpose of locating the reference points. If a
reference point does not lie on the hull surface, the screw shall be installed at declared offsets from the
reference point
, as close as reasonably possible to the reference point.

So you could put the screw in at wherever the actual waterline is and declare its x distance short of the 20.7m reference point.

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3 hours ago, Ginko said:

Aren't there 3 points (screws) located at the waterplane ? : two at the transom located 2 metres either side of centreline and one forward, similarly on the waterplane at 20.7 m. ~ these points have to be 25 mm + / - of waterplane when boat is afloat.

The forward point (screw) somewhat forces a vertical stem bow in the forward waterplane region, don't think a reverse bow is possible given the rule with respect perimeter and geometry control (of perimeter) the way I read the rule. 

Dont quite get the rule about the boat being between 20.6 and 20.7 metres given the screw locations ~ by my quick reading of rule.

 

Offsets are allowed, no?

Edit. @ hoom  :b

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44 minutes ago, hoom said:

Yes I'd forgotten that.

But also

So you could put the screw in at wherever the actual waterline is and say its x distance short of the 20.7m reference point.

Rule 3.7 at (a) and(b) defines the location points of the 3 screws 

Rule 3.8 mentions location or the reference points being at a declared offset and going onto to say reasonably close to the reference points .. .

****. how close is reasonable needs to be defined or perhaps requires further clarification ~ again I have only sped-read the rule to date.

49 minutes ago, hoom said:

Yes I'd forgotten that.

But also

So you could put the screw in at wherever the actual waterline is and say its x distance short of the 20.7m reference point.

Rule 10.6  "The maximum length of the hull shall be no less than 20.6 m and no greater than 20.7 m"

 

 

if the hull is 20.6 m then rule 3.7 at (a) needs adjustment or further defining I would think. Seems to me that waterline length is to be 20.7 m at waterplane (MWP) ~ rule 10.6 has me somewhat scratching my head at the moment given the accuracy (2mm ...) stipulated in other parts of the rule.

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The screws are to define reference points for measurement of the rest of the hull, they aren't the actual measurement.

 

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28 minutes ago, hoom said:

The screws are to define reference points for measurement of the rest of the hull, they aren't the actual measurement.

 

Don't agree with you there, there are stipulated measurements given  pursuant to Rule 3.7 ~ they define a minimum width at the transom and a rather ambiguous Station measurement at the bow (as I read) + / -    

 My take on the + / - of 25 mm is deal with water surface stability (at marina) - possibly ?

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9 hours ago, dogwatch said:

Hey, are you some kind of proton supremacist? That has me so highly charged I might just jump my orbit. Remember, without us electrons, atoms can just turn to plasma and that's so Bohring.

An Electron

I try to stay in the neutron camp :-)

Cheers,

Earl

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15 hours ago, Earl Boebert said:

Yes, again, I have read the rule. And as somebody with a bit of experience in flight control systems (I was on the verification team for the JA37B autopilot) I think they have opened a loophole that you could fly a squadron of B-17s through. Obviously, you can't make a full authority autopilot, but you can make a highly accurate pitch axis crew indicator that never sees an electron. You can also make a mechanical analog computer, equally free of electrons, that indicates what pitch axis control input is required to bring the beast back to level flight. So now you're back to carbon-based robot mode, where a crew member has the job of manually moving a control to line up with an indicator driven by a mechanical computer. If you doubt the feasibility, I suggest you read up on the C1 autopilot (used on B-17s), the Norden bombsight, and any of the multitude of mechanical fire control computers used in WWII.

I don't know if anybody will try it, but since the control system and crew indicator sections of the rule are examples of the whack-a-mole school of rule writing, it seems on first reading that this mole escaped :-) And remember, if you're building a flying machine the likes of which the world has never seen, control is your central problem (see: Wright Brothers). If you don't solve that all the lift and thrust in the world will do you no good.

Cheers,
Earl

 

Fascinating - but what/who spins the gyros?

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2 hours ago, Ginko said:

Don't agree with you there, there are stipulated measurements given  pursuant to Rule 3.7 ~ they define a minimum width at the transom and a rather ambiguous Station measurement at the bow (as I read) + / -    

 My take on the + / - of 25 mm is deal with water surface stability (at marina) - possibly ?

Pretty sure they are to be used as stated ^^ for 'measuring from' - think of them as surveyors' pegs.

Their location is known and other points can then be determined relative to them.

The fact offsets are allowed makes it pretty clear they are not there for the reasons you suggest.

(The entire structure, including these points, must be pre-supplied as a digital file, so class compliance is already determined before the measurers get to see the finished boat. Then a few quick measurements from these points will ensure the boat truly matches the supplied file - voila)

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On 11/4/2018 at 7:55 AM, barfy said:

that was painful, bandwidth from new cal better than at ETNZ base...

Is Fischer back there?

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1 hour ago, Xlot said:

 

Fascinating - but what/who spins the gyros?

I may have missed it, but I don't see any limit on stored energy for crew indicators, so clockwork or pressurized gas would work. The latter would use a simple turbine to spin the gyro. 

Cheers,

Earl

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4 hours ago, Earl Boebert said:

I may have missed it, but I don't see any limit on stored energy for crew indicators, so clockwork or pressurized gas would work. The latter would use a simple turbine to spin the gyro. 

Cheers,

Earl

Even if the gyro was battery powered that would make it electric, not electronic as specified in the rules ;-).

https://www.brightknowledge.org/engineering/electrical-and-electronic-engineering-what-s-the-difference

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41 minutes ago, rh2600 said:

Even if the gyro was battery powered that would make it electric, not electronic as specified in the rules ;-).

https://www.brightknowledge.org/engineering/electrical-and-electronic-engineering-what-s-the-difference

I posited an electron-free design because I didn't want to trigger a protest whose resolution depended on deciding the difference between electric and electronic. If you're willing to accept the risk of such a protest, then a simple indicator is a done deal: just copy the C1 autopilot roll/pitch axes design and drive  voltmeters instead of  servomotors.

It would be interesting to see if such a simple "pitch and bank" indicator (combination of an artificial horizon and  the "needle" half of a turn indicator on an aircraft) would give the pitch/roll pilot enough of an edge over somebody flying by the seat of their pants (which mode is the clear intent of the rule) that the "move the control to here" analog computer would be unnecessary. Easy to find out -- just make one and play with it on some foiling cat or other.  With 3D printing this would be a medium grade Maker Faire project.

Cheers,

Earl

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  ^ Hmm ... "Most modern appliances use a combination of electronic and electrical circuitry". If you were to rummage through military surplus stockists, most likely you'd find gyros powered by 400 Hz asynchronous motors - and electronics are bound to be in the loop

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^ His point is that you could make a 100% mechanical flight control system - or at least a 'computer' that would indicate what the guy controlling the foils needed to to, similar to the system on ETNZ. Just think vintage speedometer with a  slider next to it as opposed to a tablet with a touch screen.

It would be exponentially better than a wand, because it would not be affected by water surface texture.

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On 10/4/2018 at 9:35 PM, sclarke said:

 

 

Some interesting stuff, but this cries out to heaven: Clean - alayhi s-salām - for all his faults would never have produced such a pathetic video

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On 4/12/2018 at 10:11 AM, Earl Boebert said:

Yes, again, I have read the rule. And as somebody with a bit of experience in flight control systems (I was on the verification team for the JA37B autopilot) I think they have opened a loophole that you could fly a squadron of B-17s through. Obviously, you can't make a full authority autopilot, but you can make a highly accurate pitch axis crew indicator that never sees an electron. You can also make a mechanical analog computer, equally free of electrons, that indicates what pitch axis control input is required to bring the beast back to level flight. So now you're back to carbon-based robot mode, where a crew member has the job of manually moving a control to line up with an indicator driven by a mechanical computer. If you doubt the feasibility, I suggest you read up on the C1 autopilot (used on B-17s), the Norden bombsight, and any of the multitude of mechanical fire control computers used in WWII.

I don't know if anybody will try it, but since the control system and crew indicator sections of the rule are examples of the whack-a-mole school of rule writing, it seems on first reading that this mole escaped :-) And remember, if you're building a flying machine the likes of which the world has never seen, control is your central problem (see: Wright Brothers). If you don't solve that all the lift and thrust in the world will do you no good.

Cheers,
Earl

i guess that was my point when i pointed out this loophole with a picture of the babbage computer...an interesting direction. With all teams probably thinking "throw the ball as far as we can" who knows would happen? Thanks for your comment based on obvious expertise.

Problem is for me is that this rule will not promote "trickle on" as the team suggests they are after. Although of course no-one will share their code base, seeing what is possible would drive dev of autonomous systems to really drive these boats, rather than:

 

babage.jpg

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i haven't read the rule about daggerboards closely, but would it be an idea to have a wand on the front, leading to a mechanical device similar to the one that tuke used, suggesting optimum rake?

or is this the kind of system that you are getting at with the mechanical computer?

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it seems a bit tricky. 

Force input device described in 34.36 might allow a wand.

But control systems 20.2.c seems a bit ambiguous...and 20.1 says "control surfaces only controlled by crew", which may be the intent.

hopefully some interesting clarifications in the future.

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One wonders if we could see an arms race in analog computers. Mechanical, hydraulic, pneumatic or hybrid. People do forget quickly - it was only a bit more than a generation ago that most control systems were analog and many were all mechanical.  It would be a pretty cool thing to see. Sort of a steampunk AC.

A basic system of no more complexity than a gun director would probably be all that is needed to fly the boat. An all mechanical computer powered by compressed air could probably be made to fit inside a breadbox with a bit of effort. It only needs to stay aligned and stable for the length of each race, so error accumulation might well be kept under control without heroic effort.

Sadly they will probably just shut the loophole down.

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^ Alternatively, they might be intentionally building a little ‘space’ into the rule in case flying a 71’ boat with a soft sail on two asymmetrically arranged foils turns out to be so intractable that the sailors need a little help. But as EB noted, if he’s reading that correctly, that’s a hell of a loophole.

Having said that, noone judges the moths for using magic wands, so there is precedence for position-coupled mechanical feedback loops. Maybe somebody will come up with something really clever that would apply to other foiling classes. 

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I think they have painted themselves into an interesting corner here. If they mandate that the only legal pitch axis sensors are a crew member's eyeball and inner ear, it may not be humanly possible to control the boat in flight. If they try to limit the technology using the whack-a-mole approach a different mole may escape. The only way out that I see is to mandate the use of a standardized instrument set.

Cheers,

Earl

 

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33 minutes ago, Earl Boebert said:

If they mandate that the only legal pitch axis sensors are a crew member's eyeball and inner ear, it may not be humanly possible to control the boat in flight

 

... as a certain team is rumored to have found out on its first non-surrogate ...

 

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If a sailor can't 'sense it' it does it need to be reacted to?

Someone sailed a non-surrogate* (within weeks of the rule release?!) with an overly sensitive control set-up first time out.....big deal. It took OTUSA months to gain control of their AC72s.

"Get me a Babbage computer NOW!" Farcical.......

 

*and of course that is another insider tip that can't be shared eh - so many insiders, so many super sensitive secrets.:lol: Pics or it didn't happen

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We still haven't figured out why that exception ("unless it contains no electronic parts") was put in the rule. If a loophole results from an omission, one can consider that it was a mistake. Since it was an explicit addition, somebody must have had some reason for putting it there. You guys are the experts on the politics of the rule. What could the reason be?

Oh, and for the record, the Babbage machine is digital, not analog. 

Cheers,

Earl

 

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4 hours ago, nav said:

Someone sailed a non-surrogate* (within weeks of the rule release?! *) with an overly sensitive control set-up first time out.....big deal. It took OTUSA months to gain control of their AC72s.

The Rule's just out, but the essentials were known a long time ago - e.g. remember how/when the French came out with the "unbelievable" 15 m beam, and the 68' LOA

Pics or it didn't happen

Should be someone else's responsibility

 

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On 4/11/2018 at 9:14 AM, Earl Boebert said:

OK, I give up. 22.3.b says:

must be incapable of measuring any part of the yacht state, unless it contains no electronic parts; [emphasis mine]

Why is that exception there?

Cheers,

Earl

 

You could use mechanical sensors, like a bobweight, in the control system.  The Monitor used mechanical feedback of shroud tension to foil incidence, and feedback like that (although to the flap rather than incidence) would be allowed.

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13 hours ago, inebriated said:

i haven't read the rule about daggerboards closely, but would it be an idea to have a wand on the front, leading to a mechanical device similar to the one that tuke used, suggesting optimum rake?

or is this the kind of system that you are getting at with the mechanical computer?

Wands have been considered an appendage under previous AC rules, and thus would not be allowed because the three appendages are specified.

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5 minutes ago, Basiliscus said:

You could use mechanical sensors, like a bobweight, in the control system.  The Monitor used mechanical feedback of shroud tension to foil incidence, and feedback like that (although to the flap rather than incidence) would be allowed.

Well, if that was the intent, the door appears to be open to gyroscopes and mechanical analog computers. And if they whack that mole they'll have to decide if a pendulum-and-hydrostat indicator is legal. That was doing pitch axis control on torpedoes starting in 1868. This could go on for a while.

Cheers,

Earl

 

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11 hours ago, Earl Boebert said:

We still haven't figured out why that exception ("unless it contains no electronic parts") was put in the rule. If a loophole results from an omission, one can consider that it was a mistake. Since it was an explicit addition, somebody must have had some reason for putting it there. You guys are the experts on the politics of the rule. What could the reason be?

It could simply be a nod to the International Moth rule, which is a well-established side-step around RRS 52.

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Possibly, except that the Moth rule (I presume you're referring to 12.2) deals with actuators and not instrumentation.

Upon re-reading the rule, it appears to me that somebody realized that the first clause of 22.b.3, which includes 34.100 ("yacht state") by reference, would outlaw simple compasses. So they tacked on this exception without thinking through what it implied for the other two axes of motion. Presumably this will be fixed, and then we'll see what the fix implies :-)

Cheers,

Earl

 

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2 hours ago, Earl Boebert said:

Possibly, except that the Moth rule (I presume you're referring to 12.2) deals with actuators and not instrumentation.

 

A wand system is kind of both.

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11 minutes ago, sclarke said:

Better video quality

 

Thank goodness, been waiting and looking forward to watching it. The FB link went wrong somehow. 

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Much better vid quality, how the hell did they have such terrible quality that first time...

Interesting that they seem to have had relatively few questions from the public so that they wound up with a bunch of team member/journo hack questions.

 

Edit: they didn't look too much like they believed some of those answers >_>

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33 minutes ago, hoom said:

Much better vid quality, how the hell did they have such terrible quality that first time...

Interesting that they seem to have had relatively few questions from the public so that they wound up with a bunch of team member/journo hack questions.

 

Edit: they didn't look too much like they believed some of those answers >_>

the first video was livestreamed to the public, the second one was recorded and then posted

you can't expect to get similar quality from a live stream than a video unless you live in sweden or some shit hahahaha

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Bullshit.

We have gigabit down, 400mbit/s up residential fibre at very reasonable rates now but you don't need anywhere near that much bandwidth to stream 1080p.

VDSL is more than adequate.

The bitrate they were using for that live stream was probably not even maxing a 1Mbit/s upload on ADSL1/2.

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-0:59 "We're not allowing autopilots of any kind whether it's mechanical or electronic."

So they think.....

As to the journo hack question thing - this was hardly publicised was it?

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7 hours ago, nav said:

-0:59 "We're not allowing autopilots of any kind whether it's mechanical or electronic."

So they think.....

As to the journo hack question thing - this was hardly publicised was it?

They'll amend the rule if needs be...

But to be honest manual flight for this thing is going to be quite a challenge.

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19 hours ago, sclarke said:

Better video quality

Thanks for posting that! They're being pretty coy about the wind limits - which are a huge determinant of the approach to the hull design - and they didn't sound very convincing when they were talking about the 'post AC' life of the new boats - but it looks like they've done their homework given the extremely tight schedule.

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1 hour ago, rh2600 said:

They'll amend the rule if needs be...

But to be honest manual flight for this thing is going to be quite a challenge.

Agree on both counts. Has anybody figured out how you tack when flying upwind? Or is touchdown between tacks inevitable?

Cheers,

Earl

 

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18 minutes ago, Earl Boebert said:

Agree on both counts. Has anybody figured out how you tack when flying upwind? Or is touchdown between tacks inevitable?

Martin Fischer confirmed the hypothesis that ballast should provide inertia and facilitate flying tacks. Besides, the boat will be going upwind at 22 kts min. if on one foil; lowering the other foil, the margin to splash down is slowing to 16-18 kts

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3 minutes ago, Xlot said:

Martin Fischer confirmed the hypothesis that ballast should provide inertia and facilitate flying tacks. Besides, the boat will be going upwind at 22 kts min. if on one foil; lowering the other foil, the margin to splash down is slowing to 16-18 kts

OK, thanks. Looks like roll axis control is going to be "interesting" as well.

Cheers,

Earl

 

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Virtual perimeter of the boat to keep them from hooking foils or bouncing off of each other? Don't these guys know that rubbin' is racin'? 

"He virtually 'rubbed' you, he didn't virtually hit you."

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The big issue with the virtual box is how the heck are the crew supposed to see it?

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14 minutes ago, hoom said:

The big issue with the virtual box is how the heck are the crew supposed to see it?

I assume they will just have a giant "meters to target" readout on the back of the mast (or perhaps next to the steering wheel).

They could always get a fancy HUD.

Or they could just know it is 1m to windward of the ruddy great foil sticking up in the air!

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1 hour ago, Kiwing said:

^ I hope it is a bit more than a metre ??

Yeah. Plenty to sort ou going  forward.  

To me the driving  question is how do they dodge decapitation.

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^ Dan said they will all be in the middle of the boat! Not doing a Slingsby/Spithill hang ten.

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14 hours ago, Kiwing said:

^ I hope it is a bit more than a metre ??

True, but you get my meaning, there is almost always going to be a fucking huge point of reference sticking up for the helmsman to use to judge his distance on even without electronic aids.  Even with both foils in the water they are still going to be a pretty obvious point of reference and there is not that much underwater material sticking out beyond them.

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a big display like some of the AIS I have seen, Time to Closest Approach, Distance at Closest Approach, alarms when distance at closest approach is less than ??.

It's a user interface challenge, i know a few companies that could cook up a sweet solution, i'm sure this is an easy dev problem.

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