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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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New imoca boats

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Moreover, take a very close look at the Virbac photo. I think we are seeing a lot of fibre running fore-aft on the inside skin under the broken stringer. The laminate is biased to fore-aft for global stiffness vs rigging loads (as you would do). So the foil lift loads, if not supported by internal structures, would be working at a normal angle to the fibre bias. I think however that if is too big an if. In my opinion the lift forces (ca. 6 to 8 tonnes) would have to be carried by the substantial foil boxes and/or frames not just the shell. Such a structure can also handle reversal of the load to be sure.

These foil boxes/casings are anything but substantial. At least in the pictures I have seen. One end is attached to the hull and the other end to is supported by an end-plate that is connected to the floor and to nearby bulkhead. The hull connection should stand much more than the weight of the boat because of the force arm created by foil. The casing is quite short compared to the boat width or to the foil length.

But anyway, uplift can be easily calculated. Foils are lifted out from the water by uplift and this makes the upper limit predictable. But in case of negative angle it increases progressively as the foil submerges.

 

Some pictures of Gitana where the end plate is under construction:

http://www.gettyimages.com/detail/news-photo/picture-taken-on-may-11-2015-shows-the-new-imoca-60-news-photo/473041050

http://www.gettyimages.com/detail/news-photo/picture-taken-on-may-11-2015-shows-the-new-imoca-60-news-photo/473041046

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Moreover, take a very close look at the Virbac photo. I think we are seeing a lot of fibre running fore-aft on the inside skin under the broken stringer. The laminate is biased to fore-aft for global stiffness vs rigging loads (as you would do). So the foil lift loads, if not supported by internal structures, would be working at a normal angle to the fibre bias. I think however that if is too big an if. In my opinion the lift forces (ca. 6 to 8 tonnes) would have to be carried by the substantial foil boxes and/or frames not just the shell. Such a structure can also handle reversal of the load to be sure.

These foil boxes/casings are anything but substantial. At least in the pictures I have seen. One end is attached to the hull and the other end to is supported by an end-plate that is connected to the floor and to nearby bulkhead. The hull connection should stand much more than the weight of the boat because of the force arm created by foil. The casing is quite short compared to the boat width or to the foil length.

But anyway, uplift can be easily calculated. Foils are lifted out from the water by uplift and this makes the upper limit predictable. But in case of negative angle it increases progressively as the foil submerges.

 

Some pictures of Gitana where the end plate is under construction:

http://www.gettyimages.com/detail/news-photo/picture-taken-on-may-11-2015-shows-the-new-imoca-60-news-photo/473041050

http://www.gettyimages.com/detail/news-photo/picture-taken-on-may-11-2015-shows-the-new-imoca-60-news-photo/473041046

 

 

If the foil is under water (and it is designed to be fully) the only 2 ways that a significant about of load "increases progressively" is 1) with an increase is angle of attack (pos or neg doesn't matter, load is a linear function of CL which is approx linear with AoA until stall) or 2) an increase in speed (load a function of speed squared). Going deeper under water does increase hydrostatic pressure, but this is peanuts compared to the hydrodynamic.

 

I have seen those images of the dagger bearing supports before. You can all it in substantial or not, entirely ones opinion. It is not any different to daggerboard exits or rudder bearing foundations, really. But, it proves my point, the foil loads are carried in a structure dedicated to this purpose. Reversals of load are not loading an otherwise unprepared hull shell.

 

I see no reason to connect the presence of the foils to the structural issues yet. Certainly not from what was reported from HB by Alex and implied in photo from Virbac, both of which have everything to do with debonding or breaking of ribs. Alex is convinced it has to be an impact, though I think they may wish for a more fault tolerant system after refit.

 

What detail (if any) is available on the other boats with structural issues?

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I count 7 new rule masts.

1 normal spreader mast on SOH, which has dropped, in good conditions.

6 wing masts with deck spreaders on the mustache boats. 1 of them has not been raced yet, the other 5 are in the TJV. The one on HB has dropped.
Gitana had problems with broken mast / deck fittings (and other assorted issues) leading to an ABD, call it half a failure.

 

 

The new keel had half a failure with SOH in the BWR, repeatedly broken keel bolts. Possibly caused by sub standard material but no official verdict as far as I know. Not cool but everyone says "It's SOH, what do you expect".

 

 

That makes all dropped masts in the TJV 2015, so far, new rule masts.

2 out of 6 dropped. Not exactly good news since the new rules were written to reduce exactly that. As far as I can tell the standard mast rules also contain the relevant auxiliary mast gear and attachment points. So "But the tube did not blow up" is not really a valid counter argument in my view.

 

let's be fair: HB's mast broke after the boat was righted from a capsize, that's probably to be expected. I'm not sure if SoH was an "OD" boat because I think it may have been started before the rule was written in which case they may have been given a let off... I asked but nobody's confirmed.

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Someone more knowledgeable posted the other thread: SOH has an exemption, so no OD mast or keel.

Looks like rule 1 strikes again: Chasm has no clue. :(

 

At the time nobody really knew how the HB mast came down. (If I got that part if the interview right they were hove to with stormsail only when they got rolled by the wave.)

That leaves the mast problems on Gitana. IIRC with the mast foot and the surrounding safety catch.

 

 

 

Damage to the new rule boats. Paraphrased form my post in the other HB sinking thread

 

As I understand the interview HB had delamination damage in the fwd. watertight compartment. The skin got detached from the transverse ribs which are spaced 200mm apart. ~5 ribs affected so about 1.2m meter of hull no longer supported and flexing

Later at dock they found external scoring damage. So most likely caused by a collision that scored the 2.5mm thick skin ~2mm deep.

Expert opinion (=no me, someone from VPLP on the dock) is that similar damage to a cored boat would have cut the much thinner outer skin followed by loss of outer skin, loss of coring and then loss of inner skin in quick succession. Aka a hole.

See Sanya in the previous VOR for this damage scenario in the same position, or see a previous HB which delaminated at the start of the VG 2008(?) .

The fwd compartment is not really considered a slamming zone. The hull here is engineered for 25 tons of load, the previous generation was engineered for 20 tons. They added 25% more due to increased boat speed. Full NDT in the yard will tell much about the causes and other hidden damage. This type of damage did not happen -as far as we know- to other boats.

HB also cracked a transverse rib (in 3 places) in the sail locker area near the foil case. St.Michel-Virbac has similar damage, they cracked at least 2 ribs in roughly the same area.

No other major damage to, or problems with HB - until the rollover that is.

Gitana has problems with the mast.

Safran has problems with the side hull near a foil case, including taking water. Speculation in the TVR thread was a foil impact.

BP8 has no known problems at this time, they are informed about the problems the others had.

VPLP/Verdier shares structural information across the programs but not performance stuff. As do the teams, there are no point to be won by holding back information that could prevent someone else from sinking.

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Until all the new IMOCAs are fully checked (including PB8) we are kind of in the dark as to whether there is a common connection between their problems. It seems at the moment there were various reasons for them pulling out of the TJV, so there may not be one solution that fits all.

 

In the case of HB, hindsight (what we know it all SA posters love so much), might have suggested that a more gentle sail testing program may have been better for them, rather than straight into a tough TJV, with little sail preparation.

 

I'm looking forward to the solutions that all the teams will come up with before the start of the VG.

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Until all the new IMOCAs are fully checked (including PB8) we are kind of in the dark as to whether there is a common connection between their problems. It seems at the moment there were various reasons for them pulling out of the TJV, so there may not be one solution that fits all.

 

In the case of HB, hindsight (what we know it all SA posters love so much), might have suggested that a more gentle sail testing program may have been better for them, rather than straight into a tough TJV, with little sail preparation.

 

I'm looking forward to the solutions that all the teams will come up with before the start of the VG.

Toward facing sonar to detect UFOs.

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The sonars have a range of about 150m but with a downward angle. I doubt they'd see a container floating at the surface at 50 meters, call it two boat lengths. At 25 knots, it's a boat length every 1.4 seconds, so you have 2.8 seconds. You're in the head taking a shit, the pilot is driving, some alarm goes off. There have been 10 false alarms in the last hour due to sea state. And you do what?

 

Forward facing sonar, at these speeds, is useless for collision avoidance. Even for a 5ksb, it's useless unless you're staring at the display with the tiller in your hand.

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Until all the new IMOCAs are fully checked (including PB8) we are kind of in the dark as to whether there is a common connection between their problems. It seems at the moment there were various reasons for them pulling out of the TJV, so there may not be one solution that fits all.

 

In the case of HB, hindsight (what we know it all SA posters love so much), might have suggested that a more gentle sail testing program may have been better for them, rather than straight into a tough TJV, with little sail preparation.

 

I'm looking forward to the solutions that all the teams will come up with before the start of the VG.

Toward facing sonar to detect UFOs.

 

Safran did lots of testing over the last few editions of the VG. Really not much use.

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Moreover, take a very close look at the Virbac photo. I think we are seeing a lot of fibre running fore-aft on the inside skin under the broken stringer. The laminate is biased to fore-aft for global stiffness vs rigging loads (as you would do). So the foil lift loads, if not supported by internal structures, would be working at a normal angle to the fibre bias. I think however that if is too big an if. In my opinion the lift forces (ca. 6 to 8 tonnes) would have to be carried by the substantial foil boxes and/or frames not just the shell. Such a structure can also handle reversal of the load to be sure.

These foil boxes/casings are anything but substantial. At least in the pictures I have seen. One end is attached to the hull and the other end to is supported by an end-plate that is connected to the floor and to nearby bulkhead. The hull connection should stand much more than the weight of the boat because of the force arm created by foil. The casing is quite short compared to the boat width or to the foil length.

But anyway, uplift can be easily calculated. Foils are lifted out from the water by uplift and this makes the upper limit predictable. But in case of negative angle it increases progressively as the foil submerges.

 

Some pictures of Gitana where the end plate is under construction:

http://www.gettyimages.com/detail/news-photo/picture-taken-on-may-11-2015-shows-the-new-imoca-60-news-photo/473041050

http://www.gettyimages.com/detail/news-photo/picture-taken-on-may-11-2015-shows-the-new-imoca-60-news-photo/473041046

 

 

If the foil is under water (and it is designed to be fully) the only 2 ways that a significant about of load "increases progressively" is 1) with an increase is angle of attack (pos or neg doesn't matter, load is a linear function of CL which is approx linear with AoA until stall) or 2) an increase in speed (load a function of speed squared). Going deeper under water does increase hydrostatic pressure, but this is peanuts compared to the hydrodynamic.

I doubt that foils are designed to be fully submerged all the time. We all have seen pictures of Gitana flying above the water only small section of stern, tip of the foil and keel touching the water. I know, the foil is not that effective when partially submerged because of cavitation and other effects. But it doesn't have to be. What I meant was that uplift destroys it self and this is therefore self stabilizing system. But down force can only go stronger even if the smallest section of the foil touches the water with negative attacking angle.

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Moreover, take a very close look at the Virbac photo. I think we are seeing a lot of fibre running fore-aft on the inside skin under the broken stringer. The laminate is biased to fore-aft for global stiffness vs rigging loads (as you would do). So the foil lift loads, if not supported by internal structures, would be working at a normal angle to the fibre bias. I think however that if is too big an if. In my opinion the lift forces (ca. 6 to 8 tonnes) would have to be carried by the substantial foil boxes and/or frames not just the shell. Such a structure can also handle reversal of the load to be sure.

These foil boxes/casings are anything but substantial. At least in the pictures I have seen. One end is attached to the hull and the other end to is supported by an end-plate that is connected to the floor and to nearby bulkhead. The hull connection should stand much more than the weight of the boat because of the force arm created by foil. The casing is quite short compared to the boat width or to the foil length.

But anyway, uplift can be easily calculated. Foils are lifted out from the water by uplift and this makes the upper limit predictable. But in case of negative angle it increases progressively as the foil submerges.

 

Some pictures of Gitana where the end plate is under construction:

http://www.gettyimages.com/detail/news-photo/picture-taken-on-may-11-2015-shows-the-new-imoca-60-news-photo/473041050

http://www.gettyimages.com/detail/news-photo/picture-taken-on-may-11-2015-shows-the-new-imoca-60-news-photo/473041046

 

 

If the foil is under water (and it is designed to be fully) the only 2 ways that a significant about of load "increases progressively" is 1) with an increase is angle of attack (pos or neg doesn't matter, load is a linear function of CL which is approx linear with AoA until stall) or 2) an increase in speed (load a function of speed squared). Going deeper under water does increase hydrostatic pressure, but this is peanuts compared to the hydrodynamic.

I doubt that foils are designed to be fully submerged all the time. We all have seen pictures of Gitana flying above the water only small section of stern, tip of the foil and keel touching the water. I know, the foil is not that effective when partially submerged because of cavitation and other effects. But it doesn't have to be. What I meant was that uplift destroys it self and this is therefore self stabilizing system. But down force can only go stronger even if the smallest section of the foil touches the water with negative attacking angle.

 

...agreed; also, with foil upper surfaces immersed the foil will exert equal and opposite downward reactions to any upward shock load until the shock causes it to cavitate underneath. This could make the boat more susceptible to damage due to slamming than a boat without immersed foils.

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The fwd compartment is not really considered a slamming zone. The hull here is engineered for 25 tons of load, the previous generation was engineered for 20 tons. They added 25% more due to increased boat speed. Full NDT in the yard will tell much about the causes and other hidden damage. This type of damage did not happen -as far as we know- to other boats.

I was surprised when I heard it. 25 tons per square meter is nothing significant. It equal to 2,5kg per square centimeter. So you should be able to push your thumb through the hull. You get same rigidness from inflatable if you pump 2,5atm pressure into it. I begun to wonder what will be the next step? Make the bow section even thinner and use air pressure instead of stringers to reinforce it.

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The fwd compartment is not really considered a slamming zone. The hull here is engineered for 25 tons of load, the previous generation was engineered for 20 tons. They added 25% more due to increased boat speed. Full NDT in the yard will tell much about the causes and other hidden damage. This type of damage did not happen -as far as we know- to other boats.

I was surprised when I heard it. 25 tons per square meter is nothing significant. It equal to 2,5kg per square centimeter. So you should be able to push your thumb through the hull. You get same rigidness from inflatable if you pump 2,5atm pressure into it. I begun to wonder what will be the next step? Make the bow section even thinner and use air pressure instead of stringers to reinforce it.

 

 

Why not pressurize the bow with hydrogen instead, would be a "safe" and sound solution.

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The fwd compartment is not really considered a slamming zone. The hull here is engineered for 25 tons of load, the previous generation was engineered for 20 tons. They added 25% more due to increased boat speed. Full NDT in the yard will tell much about the causes and other hidden damage. This type of damage did not happen -as far as we know- to other boats.

I was surprised when I heard it. 25 tons per square meter is nothing significant. It equal to 2,5kg per square centimeter. So you should be able to push your thumb through the hull. You get same rigidness from inflatable if you pump 2,5atm pressure into it. I begun to wonder what will be the next step? Make the bow section even thinner and use air pressure instead of stringers to reinforce it.

 

 

Why not pressurize the bow with hydrogen instead, would be a "safe" and sound solution.

 

 

Hydrogen reminds me too much of Hindenburg, really....

But air is obviously too heavy.

Try helium.

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Helium! Imagine those macho skippers with long beards going for a sail change in the forward compartment and coming back talking like Donald Duck!

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With all the aero consideration and optimization of everything for speed why do they fly those big flags off the shrouds? They look cool but the drag must be considerable.

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With all the aero consideration and optimization of everything for speed why do they fly those big flags off the shrouds? They look cool but the drag must be considerable.

For sponsors.

 

Pretty sure when they are out in the sea they will furl or remove these flags.

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The fwd compartment is not really considered a slamming zone. The hull here is engineered for 25 tons of load, the previous generation was engineered for 20 tons. They added 25% more due to increased boat speed. Full NDT in the yard will tell much about the causes and other hidden damage. This type of damage did not happen -as far as we know- to other boats.

I was surprised when I heard it. 25 tons per square meter is nothing significant. It equal to 2,5kg per square centimeter. So you should be able to push your thumb through the hull. You get same rigidness from inflatable if you pump 2,5atm pressure into it. I begun to wonder what will be the next step? Make the bow section even thinner and use air pressure instead of stringers to reinforce it.

 

 

Why not pressurize the bow with hydrogen instead, would be a "safe" and sound solution.

 

 

Hydrogen reminds me too much of Hindenburg, really....

But air is obviously too heavy.

Try helium.

 

I know, it is hard to take it seriously. But to pressurize whole forward compartment wasn't my idea.

 

Lets face it. Current solution with rigid stringers is hopeless. Even if they manage to get it right and slamming is not an issue any more, even if it can survive all kind of weather, you still gonna hit something solid in first 1000 miles and you race will be over. Those broken ribs are impossible to fix and you have to build a new hull.

 

Current single-skinned hulls can survive impacts quit well. Hull can flex instead of breaking. The only weak point is stringer-design. Easy solution would be to make similar rigid ribs but to place those a bit higher. The gap between hull and ribs should be filled with something like an airbag. I am quite sure that the next generation will be built using similar technology and the hull will be made even thinner.

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Something I found relevant and very interesting is this site, that includes a detailed and scathing commentary of boat building and the use of cored hulls. The commentary is almost exclusively about firbreglass hulls and mostly devoted to larger powerboats. But the principles remain valid, and for something like an IMOCA 60 very valid. Both for the hull shape (large areas of near flat surfaces) and the speeds, and thus slamming endured. He is also not convinced the aviation industry has it together either.

 

The TL;DR summary.

 

Site is written by David Pascoe, a now retired marine surveyor. He has a particular dislike of cored hulls in areas where there is significant stress, as he basically considers it a flawed design paradigm. One that guarantees eventual failure of the hull. He makes a point that the (power) boat building industry has gone though a number of cycles where cored hulls have been favoured, mostly because they used less materials. For power boats this meant cheaper, rather than simply lighter. When not cored, the hulls are built with ribs and stringers. Just like we see on the new IMOCA designs. It isn't that the ribs are new at all. David would probably say that the modern boats are a return to sensible design principles that were forgotten in the unseemly haste to embrace the flawed attributes of cored hull design.

 

No doubt, the failures we saw in the last few VOR rounds exactly match his predictions. It takes only a small breach of the hull in an area of slamming or significant water speed to result in very fast failure of a large area of the hull structure. Also the shearing loads within the core result in fracturing of the core in areas with compound curves. Sanya's collision damage and Ericsson-3's core failure exemplify exactly these two modes.

 

So, the answer may well be that we are seeing a swing back against core, and, should they get it right (which is clearly an issue) we may be seeing hulls with better longevity and resilience. No doubt coring boats with aluminium or nomex honeycomb is an exercise in blind faith. You absolutely trust that the core won't ever get wet. Something that is intrinsically impossible in the long term. All composite hulls are permeable to some extent. Layups with pre-preg are probably the best, as there is not the same scope for errant fibres to provide a wicking path for moisture. But from the moment they hit the water the clock is ticking.

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The persico video is interesting in seeing the multiple transverse ribs, but seems a bit odd to be stiffening the panels in the direction that is alrady stiff by virtue of the section shape and not in the longitudinal direction that is the one that has no form stiffness.

 

In terms of damage survivability, then cored laminates with skin links and some kevlar in the laminates proved itself to be extremely damage tolerant, and we used to still be racing with the the carbon/kevlar skins flapping off the core!

 

Maybe IMOCA should have concentrated its efforts on some basic hull structural issues along with the keel and left the rigs well alone, as that would have kept some of the design freedom that has been castrated in the current format.

 

Any structural engineers care to comment on the multiple transverse rib arrangements? I can't make much sense of that, nor can some of my past co-workers in the field.

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The persico video is interesting in seeing the multiple transverse ribs, but seems a bit odd to be stiffening the panels in the direction that is alrady stiff by virtue of the section shape and not in the longitudinal direction that is the one that has no form stiffness.

 

In terms of damage survivability, then cored laminates with skin links and some kevlar in the laminates proved itself to be extremely damage tolerant, and we used to still be racing with the the carbon/kevlar skins flapping off the core!

 

Maybe IMOCA should have concentrated its efforts on some basic hull structural issues along with the keel and left the rigs well alone, as that would have kept some of the design freedom that has been castrated in the current format.

 

Any structural engineers care to comment on the multiple transverse rib arrangements? I can't make much sense of that, nor can some of my past co-workers in the field.

GBH

 

this is really a different structure layout compare to what we have seen of Gitana in photos. Gitana seems to be cored aft of the keel everywhere.

 

Mental exercise - take a piece of plastic sheet, like a binder cover or something. Hold it so it has a radius of curvature in one direction. You do not need stiffeners in the the direction the is parallel, it has inherent stiffness IN THAT DIRECTION because of curvature. But you do in the direction that is in fact curved. Because in a thin sheet it is easy to make more or less radius, provided it is only in the one plane. The stiffeners in that orientation also conform to small panels edges in the fore-aft direction (where you will put more axial fibre for global stiffness).

 

So, I also can generally agree with survivability of cored structures, usually. Engineered a number of high speed power boats with core all over, kevlar in the skins, and had good results. But if you have decided to eliminate the weak link in the chain - core bond - I can also understand this method.

 

Note that unlike the Green build of HB, relying APPARENTLY completely on glued flanges of moulded frames (not bad) the Persico built VDS has relied completely on secondary bonding of covers over formers (just a bit better).

 

Moreover, as to whether IMOCA should have concentrated or "one-designed" hull and deck structures, I disagree. For one, they should not. Nor should the masts or keels be so. This kind of step always trades real development for microscopic improvements at greater cost.

 

For another, nothing is really changed, single skin hulls with frames is not new at all. If anything has been changed it has been reverting to transverse primary stiffeners, more frequent than before, and thinner skins. And to that point 3.5 to 4 mm thick doesn't much phase me. But 2.5 does. That seems really close to the bone. I have only done a bit of math on it, but it didn't look promising.

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Did we see pictures of HB?

Looking at the better version of the StMichel-Virbac damage rib construction looks similar to me. Hull, intermediate layer, foam core forming the rib incl. fairing to define all radius, another intermediate layer, top layer. Different weave pattens in the outer layers.

 

2.5mm to keep the weight down, Alex said in the first interview that is is a bit on the thin side - but not excessively so. Race boat skippers, anorexic, all of them. ;) My guess it that further back where loads go up the hull skin gets thicker. More foot traffic too.

 

Kevlar, would it be allowed? Class rules only talk about carbon with particular performance limits as hull fibre.

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Thank you ST, but thats not really quite true in the cse of the 60s as they are so flat, if tubulur or more normal canoe bodies then I'd agree but transverse curvature in the bottom panel is extremely low and to my eye it seems like an unbalanced sort of arrangement. Now geodetic framing and you'd be talking when using thin skins!

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Some excellent commentary here....would be interesting being a fly on the wall inside VLVP/Verdier.

 

One thing to remember though when debating the merits of otherwise of one-design elements is that a lot of those outcomes are directed at keeping the previous generation of boats competitive. We therefore may have to wait a bit for changes in some areas, particularly with the $ involved. The Mini Proto's on the other hand have the luxury of being a bit faster in adopting changes to accommodate new thinking.

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Thank you ST, but thats not really quite true in the cse of the 60s as they are so flat, if tubulur or more normal canoe bodies then I'd agree but transverse curvature in the bottom panel is extremely low and to my eye it seems like an unbalanced sort of arrangement. Now geodetic framing and you'd be talking when using thin skins!

 

GBH, in the flat aft end of the VDS you see no such ribs. There is surely core there, whether more impact resistant high elongation 100+ kg/m2 foam or kevlar honeycomb, I cannot be sure. What I said about the usefulness of the stiffeners really does apply to the rounded areas below the chine and to the bow.

 

I am not sold on the fault tolerance of this arrangement, but there is a fundamental logic there.

 

I reckon they will bond the ribs back down and reduce their span by 1/2 (additional deep longitudinals over the top) and it will not be an issue again, unless NDT or samples removed show a fundamental gluing problem between rib and skin.

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Adding some longs over the top F&A will certainly deal with the likely issues, but then you have to think there would have been easier ways of dealing with the structure up there for the weight saving - which will probably disappear now! And if there is genuinely only 2.5 mm carbon skin between the ribs then damn sure I wouldn't be happy with that, way too easy to puncture on something quite small and pointy, some of the right sort of foam core has a lot more tolerance in that respect for energy absorbtion.

Full carbon and brittle skin - not convinced at all.

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http://www.sailingworld.com/new-generation-imoca?src=SOC&dom=fb

 

Foiling Imocas. Some interesting points on foil design and stress on mast because of additional righting moment.

Also broader reaching means that the optimal routing for new boats differ from the old ones, which we saw in the first part of TJV

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Adding some longs over the top F&A will certainly deal with the likely issues, but then you have to think there would have been easier ways of dealing with the structure up there for the weight saving - which will probably disappear now! And if there is genuinely only 2.5 mm carbon skin between the ribs then damn sure I wouldn't be happy with that, way too easy to puncture on something quite small and pointy, some of the right sort of foam core has a lot more tolerance in that respect for energy absorbtion.

Full carbon and brittle skin - not convinced at all.

Sorry, not buying into the carbon = brittle argument. That is ancient, and has no bearing on properly conceived laminates. If you mean that unidirectional fibres have less strain to failure than ... fill in blank ... well that is true. But brittle depends on many choices.

 

Kind of agree about absorption of energy but more in the skins than in the core.

 

Something small and pointy will always get through if position is bad - it is a skin designed around the concept of normal pressure over an area.

 

As for weight saving, I think the point of the design is to save weight, yes, but with the desire to remove the skin-core bond first and foremost.

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Adding some longs over the top F&A will certainly deal with the likely issues, but then you have to think there would have been easier ways of dealing with the structure up there for the weight saving - which will probably disappear now! And if there is genuinely only 2.5 mm carbon skin between the ribs then damn sure I wouldn't be happy with that, way too easy to puncture on something quite small and pointy, some of the right sort of foam core has a lot more tolerance in that respect for energy absorbtion.

Full carbon and brittle skin - not convinced at all.

Sorry, not buying into the carbon = brittle argument. That is ancient, and has no bearing on properly conceived laminates. If you mean that unidirectional fibres have less strain to failure than ... fill in blank ... well that is true. But brittle depends on many choices.

 

Kind of agree about absorption of energy but more in the skins than in the core.

 

Something small and pointy will always get through if position is bad - it is a skin designed around the concept of normal pressure over an area.

 

As for weight saving, I think the point of the design is to save weight, yes, but with the desire to remove the skin-core bond first and foremost.

 

 

That's the next question ! Although I do not know much about procedures used, I am not too sure that the skin-ribs bonding is done in as good curing conditions as those developed for skin-core bonds along the years.

That would be interesting to know.

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When the people discussing materials and construction methods are talking about structures "absorbing energy", what energy absorption mechanisms are they talking about? A linear elastic structure where the materials are operating within the elastic limit, does not absorb energy, by definition. If materials are strained beyond the elastic limit, (yield point) the structure is in a "shake down" condition where energy is absorbed by plastic strain or local fracturing at stress concentrations, which can re-distribute load to parts of the structure which have not yet been strained beyond the yield point. This can occur either way without catastrophic failure. Carbon steel is the classic material that does this due to plastic strain, i.e. it yields, extends plastically and its strength increases and during this process the structure absorbs energy.

If the material is inherently brittle and cracks locally when overstressed and does not work harden, then the structure can still absorb some energy without catastrophic failure but the areas which have exceeded yield point have been weakened and not strengthened, and the structure may become sensitive to fatigue which will cause the cracks to grow until the structure fails.

The other type of material behaviour at high elongations (several percent) is hysterysis in which a non-linear elastic material (such as rubbers or elastomers, and elastomeric foams) can absorb a measure of energy every time they experience a stress cycle without deteriorating.

It seems to me that it could well be possible for a double skinned carbon fibre structure which uses a polymer foam to separate the two skins, to absorb energy without the foam or the skin-to-foam bond being broken and that the foam might have a very low modulus compared with the carbon laminate and that such a structure could sustain impact loads and absorb energy. The outside skin could be displaced inwards by some mms relative to the main structure of the boat over large areas of hull surface every time the boat slams, without anything exceeding yield stress.

My knowledge of carbon fibre laminate behaviour is minimal but I had assumed that the fully cured laminate is very strong but is essentially brittle in that it once its yield point is exceeded it starts to break up, and then until it yields it will be linearly elastic and will not absorb energy.

All in all this suggests to me that a foam cored hull could sustain a lot more slamming than a single skin which is supported by very stiff stringers. The latter construction could not sustain any significant displacement of the outside skin relative to the internal structure of the boat, but the foam cored one can.

If one considers a specific slam, in engineering terms, as an impulse of given magnitude. Rate of change of momentum, force times time, the impulse on the foam cored structure will cause a larger displacement which will occur over a longer time period leading to a proportionately lower magnitude of peak stresses imposed on the structure.

I would be interested to hear what people who have experience in carbon materials and foams have to say on the above?

Personally I don't much like the foam cored construction because its impossible to keep inspecting it. If the materials deteriorate it will be hard to notice what is going on and it will be difficult to repair, but from the materials and structural viewpoints I do think it can perform much better to resist slamming.

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I'm not a builder, but yes structural foam cored laminates, of glass, Kevlar, carbon, etc, have been in use for many years, Its well established in boat building applications, it is easy to repair, easy to work with, and easy to trouble shoot damage.

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When the people discussing materials and construction methods are talking about structures "absorbing energy", what energy absorption mechanisms are they talking about? A linear elastic structure where the materials are operating within the elastic limit, does not absorb energy, by definition. If materials are strained beyond the elastic limit, (yield point) the structure is in a "shake down" condition where energy is absorbed by plastic strain or local fracturing at stress concentrations, which can re-distribute load to parts of the structure which have not yet been strained beyond the yield point. This can occur either way without catastrophic failure. Carbon steel is the classic material that does this due to plastic strain, i.e. it yields, extends plastically and its strength increases and during this process the structure absorbs energy.

If the material is inherently brittle and cracks locally when overstressed and does not work harden, then the structure can still absorb some energy without catastrophic failure but the areas which have exceeded yield point have been weakened and not strengthened, and the structure may become sensitive to fatigue which will cause the cracks to grow until the structure fails.

The other type of material behaviour at high elongations (several percent) is hysterysis in which a non-linear elastic material (such as rubbers or elastomers, and elastomeric foams) can absorb a measure of energy every time they experience a stress cycle without deteriorating.

It seems to me that it could well be possible for a double skinned carbon fibre structure which uses a polymer foam to separate the two skins, to absorb energy without the foam or the skin-to-foam bond being broken and that the foam might have a very low modulus compared with the carbon laminate and that such a structure could sustain impact loads and absorb energy. The outside skin could be displaced inwards by some mms relative to the main structure of the boat over large areas of hull surface every time the boat slams, without anything exceeding yield stress.

My knowledge of carbon fibre laminate behaviour is minimal but I had assumed that the fully cured laminate is very strong but is essentially brittle in that it once its yield point is exceeded it starts to break up, and then until it yields it will be linearly elastic and will not absorb energy.

All in all this suggests to me that a foam cored hull could sustain a lot more slamming than a single skin which is supported by very stiff stringers. The latter construction could not sustain any significant displacement of the outside skin relative to the internal structure of the boat, but the foam cored one can.

If one considers a specific slam, in engineering terms, as an impulse of given magnitude. Rate of change of momentum, force times time, the impulse on the foam cored structure will cause a larger displacement which will occur over a longer time period leading to a proportionately lower magnitude of peak stresses imposed on the structure.

I would be interested to hear what people who have experience in carbon materials and foams have to say on the above?

Personally I don't much like the foam cored construction because its impossible to keep inspecting it. If the materials deteriorate it will be hard to notice what is going on and it will be difficult to repair, but from the materials and structural viewpoints I do think it can perform much better to resist slamming.

 

I don't think that's correct. 'Absorbing energy' requires deflection (like a spring), so what you are suggesting is that a cored laminate can deflect further than a monolithic laminate before there is structural failure. But if you examine the range of likely cases, I don't see how that could be true:

 

Case 1 - cored panel has same stiffness as monolithic panel. In this instance, the cored panel would be lighter becuase it requires less carbon to achieve stiffness due to I beam effect of core. So overall tensile strength is lower, plus the core itself will fail at some point, plus you've introduced the possibility of one of the skins buckiling under compression.

 

Case 2 - cored panel has same (or greater) tensile strength as monolithic panel. This would basically require the same total amount of carbon, so the cored panel would be both heavier and stiffer. This is a more likely scenario, with the calculation having been made that the weight of the ribs required to stiffen the monolithic panel is less than that of the core, plus contributes to tensile strength since ribs are also carbon. I don't see how the monolithic structure - if properly designed and implemented - would not be far superior to a cored structure for continous impact etc, and in fact isn't this why they switched to monolithic laminates in the impact zones of the Volvo 70s?

 

I think what we are really looking at here is a structural design criteria that was developed over years on non-foiling boats now needing to be rethought to some extent due to higher speeds and a load distribution that is even more concentrated in specific areas than anyone anticipated. The reality is that modeling can only go so far, and at some point, the theoretical rubber needs to meet the real world road, and you are going to learn something.

 

I expect that the designers have learned more than enough from the various failures (and successes) to very effectively mod the boats in a way that will make them as tough as they will need to be.

 

 

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"I expect that the designers have learned more than enough from the various failures (and successes) to very effectively mod the boats in a way that will make them as tough as they will need to be."

 

Famous last words?

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"I expect that the designers have learned more than enough from the various failures (and successes) to very effectively mod the boats in a way that will make them as tough as they will need to be."

 

Famous last words?

Yep.

 

LOL

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I would say that staysail has got it pretty much right. The problem is that when designers specify a "foam" core there are a range of choices. Those that adsorb energy are heavier, and in a boat like a IMOCA 60, designers simply stay away. They seem to settle on Nomex honeycomb as the default core material, or worse - aluminium honeycomb. Nomex sounds high tech. It is paper. Brittle paper. And it fails it if gets wet. Aluminium honeycomb almost dissolves in seawater. Being little thicker than heavy foil it has almost zero resilience against stress corrosion. Get it wet in seawater and then slam it across an ocean and you may be met with thick slurry of aluminium chlorides rather than honeycomb holding your carbon skins apart. Both core materials have very poor resilience, adsorb little to no energy, Nomex fractures easily, and both have a use by date after which the hull becomes a write off. But they are light. And if you want to win a race, you will vote for light every time.

 

To understand a cored laminate, consider an I beam. The top and bottom of the beam are in ether compression of extension, and the modulus of the material determines how much the beam flexes. The job of the I in the beam is simply to keep the top and bottom apart at a constant distance. Which is a fine static view. But as the beam is stressed, and does bend, observe that the bending of the beam results in the I distorting with a shearing force. One side is pulled wider, and the other compressed. In a core the same occurs. The shearing stresses in the core can adsorb energy if the core material is so chosen. (Or the core can fail in response to the shear. ) The motion over which the core shears and adsorbs energy can be well within the safe strain seen by the skin materials.

 

The VO-70 rules mandated a foam core for areas subject to slamming loads, and they mandated the density of foam. But the extent of the foam was across those areas where they thought the loads would be high, and experience suggests that the extent was a little short. Erricson-3's hull failure involved the Nomex core fracturing - it did not delaminate from either carbon layer.

 

Trouble with foam is that you can have all sorts of different polymers, densities and porosities. Some foams crumble eventually, and many are porous. Resilience comes from the presence of plasticisers in the polymer mix, and these eventually evaporate and leave the foam brittle.

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I would say that staysail has got it pretty much right. The problem is that when designers specify a "foam" core there are a range of choices. Those that adsorb energy are heavier, and in a boat like a IMOCA 60, designers simply stay away. They seem to settle on Nomex honeycomb as the default core material, or worse - aluminium honeycomb. Nomex sounds high tech. It is paper. Brittle paper. And it fails it if gets wet. Aluminium honeycomb almost dissolves in seawater. Being little thicker than heavy foil it has almost zero resilience against stress corrosion. Get it wet in seawater and then slam it across an ocean and you may be met with thick slurry of aluminium chlorides rather than honeycomb holding your carbon skins apart. Both core materials have very poor resilience, adsorb little to no energy, Nomex fractures easily, and both have a use by date after which the hull becomes a write off. But they are light. And if you want to win a race, you will vote for light every time.

 

To understand a cored laminate, consider an I beam. The top and bottom of the beam are in ether compression of extension, and the modulus of the material determines how much the beam flexes. The job of the I in the beam is simply to keep the top and bottom apart at a constant distance. Which is a fine static view. But as the beam is stressed, and does bend, observe that the bending of the beam results in the I distorting with a shearing force. One side is pulled wider, and the other compressed. In a core the same occurs. The shearing stresses in the core can adsorb energy if the core material is so chosen. (Or the core can fail in response to the shear. ) The motion over which the core shears and adsorbs energy can be well within the safe strain seen by the skin materials.

 

The VO-70 rules mandated a foam core for areas subject to slamming loads, and they mandated the density of foam. But the extent of the foam was across those areas where they thought the loads would be high, and experience suggests that the extent was a little short. Erricson-3's hull failure involved the Nomex core fracturing - it did not delaminate from either carbon layer.

 

Trouble with foam is that you can have all sorts of different polymers, densities and porosities. Some foams crumble eventually, and many are porous. Resilience comes from the presence of plasticisers in the polymer mix, and these eventually evaporate and leave the foam brittle.

 

Don't know of any modern high quality foam core that is porous, they may suffer from shear failiure and appear to crumble in that area, but they dont just crumble by themselves.

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Very interesting thoughts! Your comment regarding a "buffer" between the ribs and the hull I found fascinating. On Thursdays Child, an older iteration of the open 60 class, we used a B&R (Bergstrom and Ritter) "space frame" concept inside a foam core hull. As the structural result of the space frame essentially ties the keel and rig together into a contiguous structure within the hull the need for a more robust bonding system became apparent. When we launched off just a 10' or so wave in the Gulfstream and free fell into the trough the entire internal structure rotated within the hull a few inches necessitating re-bonding the internal framework to the hull. I see where you are going with this and like it. Now it sounds like an engineering problem.

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I would say that staysail has got it pretty much right. The problem is that when designers specify a "foam" core there are a range of choices. Those that adsorb energy are heavier, and in a boat like a IMOCA 60, designers simply stay away. They seem to settle on Nomex honeycomb as the default core material, or worse - aluminium honeycomb. Nomex sounds high tech. It is paper. Brittle paper. And it fails it if gets wet. Aluminium honeycomb almost dissolves in seawater. Being little thicker than heavy foil it has almost zero resilience against stress corrosion. Get it wet in seawater and then slam it across an ocean and you may be met with thick slurry of aluminium chlorides rather than honeycomb holding your carbon skins apart. Both core materials have very poor resilience, adsorb little to no energy, Nomex fractures easily, and both have a use by date after which the hull becomes a write off. But they are light. And if you want to win a race, you will vote for light every time.

 

To understand a cored laminate, consider an I beam. The top and bottom of the beam are in ether compression of extension, and the modulus of the material determines how much the beam flexes. The job of the I in the beam is simply to keep the top and bottom apart at a constant distance. Which is a fine static view. But as the beam is stressed, and does bend, observe that the bending of the beam results in the I distorting with a shearing force. One side is pulled wider, and the other compressed. In a core the same occurs. The shearing stresses in the core can adsorb energy if the core material is so chosen. (Or the core can fail in response to the shear. ) The motion over which the core shears and adsorbs energy can be well within the safe strain seen by the skin materials.

 

The VO-70 rules mandated a foam core for areas subject to slamming loads, and they mandated the density of foam. But the extent of the foam was across those areas where they thought the loads would be high, and experience suggests that the extent was a little short. Erricson-3's hull failure involved the Nomex core fracturing - it did not delaminate from either carbon layer.

 

Trouble with foam is that you can have all sorts of different polymers, densities and porosities. Some foams crumble eventually, and many are porous. Resilience comes from the presence of plasticisers in the polymer mix, and these eventually evaporate and leave the foam brittle.

 

That's the thing - at the end, it comes down to optimizing strength and stiffness vs weight and impact strength. There is no magic bullet in design, but here the calculation seems to be that cores have more downside than upside. Time will tell.

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Very interesting thoughts! Your comment regarding a "buffer" between the ribs and the hull I found fascinating. On Thursdays Child, an older iteration of the open 60 class, we used a B&R (Bergstrom and Ritter) "space frame" concept inside a foam core hull. As the structural result of the space frame essentially ties the keel and rig together into a contiguous structure within the hull the need for a more robust bonding system became apparent. When we launched off just a 10' or so wave in the Gulfstream and free fell into the trough the entire internal structure rotated within the hull a few inches necessitating re-bonding the internal framework to the hull. I see where you are going with this and like it. Now it sounds like an engineering problem.

 

I believe Imp was the first design with the B&R spaceframe, is that correct? Imagine an all carbon spaceframe, with a slightly decoupled monocoqque carbon shell that could move just enough relative to the central mass of the boat (keel, principle structure, rig, foils etc) so that it could absorb impact loads...now THAT would be interesting!

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Great read staysail! I have often wondered why carbon, which is so brittle, is so frequently placed in an epoxy matrix. Both materials be brittle in nature. I had experience with a foam core constructed hull, Kevlar, carbon and bidirectional S-glass in a vinylester resin. Due to the secondary bonding issues associated with vinylester the laminate was always done wet on wet and the relative elasticity of the vinylester combined with the brittle strength of the carbon made for one really tough hull! It took us six years to get it to fail and we were not kind to the old girl!

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Very interesting thoughts! Your comment regarding a "buffer" between the ribs and the hull I found fascinating. On Thursdays Child, an older iteration of the open 60 class, we used a B&R (Bergstrom and Ritter) "space frame" concept inside a foam core hull. As the structural result of the space frame essentially ties the keel and rig together into a contiguous structure within the hull the need for a more robust bonding system became apparent. When we launched off just a 10' or so wave in the Gulfstream and free fell into the trough the entire internal structure rotated within the hull a few inches necessitating re-bonding the internal framework to the hull. I see where you are going with this and like it. Now it sounds like an engineering problem.

 

I believe Imp was the first design with the B&R spaceframe, is that correct? Imagine an all carbon spaceframe, with a slightly decoupled monocoqque carbon shell that could move just enough relative to the central mass of the boat (keel, principle structure, rig, foils etc) so that it could absorb impact loads...now THAT would be interesting!

 

"Business Machine" a Kiwi 24 1/4 was the first "space frame"......I built as co owner/founder of Kiwi boats

post-56533-0-48601900-1447443409_thumb.jpg

post-56533-0-75674300-1447443418_thumb.jpg

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Very interesting thoughts! Your comment regarding a "buffer" between the ribs and the hull I found fascinating. On Thursdays Child, an older iteration of the open 60 class, we used a B&R (Bergstrom and Ritter) "space frame" concept inside a foam core hull. As the structural result of the space frame essentially ties the keel and rig together into a contiguous structure within the hull the need for a more robust bonding system became apparent. When we launched off just a 10' or so wave in the Gulfstream and free fell into the trough the entire internal structure rotated within the hull a few inches necessitating re-bonding the internal framework to the hull. I see where you are going with this and like it. Now it sounds like an engineering problem.

 

I believe Imp was the first design with the B&R spaceframe, is that correct? Imagine an all carbon spaceframe, with a slightly decoupled monocoqque carbon shell that could move just enough relative to the central mass of the boat (keel, principle structure, rig, foils etc) so that it could absorb impact loads...now THAT would be interesting!

 

"Business Machine" a Kiwi 24 1/4 was the first "space frame"......I built as co owner/founder of Kiwi boats

 

 

Forgot about that one - but it's all coming back now, like an LSD flashback! Thanks - what a cool chunk of history!

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Very interesting thoughts! Your comment regarding a "buffer" between the ribs and the hull I found fascinating. On Thursdays Child, an older iteration of the open 60 class, we used a B&R (Bergstrom and Ritter) "space frame" concept inside a foam core hull. As the structural result of the space frame essentially ties the keel and rig together into a contiguous structure within the hull the need for a more robust bonding system became apparent. When we launched off just a 10' or so wave in the Gulfstream and free fell into the trough the entire internal structure rotated within the hull a few inches necessitating re-bonding the internal framework to the hull. I see where you are going with this and like it. Now it sounds like an engineering problem.

 

I believe Imp was the first design with the B&R spaceframe, is that correct? Imagine an all carbon spaceframe, with a slightly decoupled monocoqque carbon shell that could move just enough relative to the central mass of the boat (keel, principle structure, rig, foils etc) so that it could absorb impact loads...now THAT would be interesting!

 

"Business Machine" a Kiwi 24 1/4 was the first "space frame"......I built as co owner/founder of Kiwi boats

 

 

Forgot about that one - but it's all coming back now, like an LSD flashback! Thanks - what a cool chunk of history!

 

for your enjoyment surfsailor~~~~

post-56533-0-03843600-1447445095_thumb.jpg

post-56533-0-35375100-1447445126_thumb.jpg

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Me being a bit conservative, my new ride is a vacuum infused closed cell foam construction. I am planning on keeping this one for years, so I spent a lot of time researching construction techniques and hull material. Our hull layup uses a combination of foams, high impact areas being linear PVC foam. I probably drove the manufacturer nuts with dumb questions and trying to understand the materials, as I am no expert.

One of the impressive things was looking at data of high impact foam shock loads derived from racing power boats wave-slamming at 100mph, seriously impressive. Another thing I didn't know is these foam construction techniques can torque up between the inner and outer layers to absorb energy under high impact loads. This area of composites and construction I find fascinating, I just wish I knew more about it.

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There will be a point of diminishing returns with foils. There is drag inherent in generating lift and at some point the lift required to lift the boat higher will generate more drag than would be desirable.

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There will be a point of diminishing returns with foils. There is drag inherent in generating lift and at some point the lift required to lift the boat higher will generate more drag than would be desirable.

Sure lift and drag are related, but as for the rest of your post:-

Why?

At what point?

Explain?

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^^ Thanks.

 

Like this part of the translation: foils needed to win, so worth the effort to fix.

The victory in the Transat Jacques Vabre a boat not equipped with foils, he questioned your choice?

Philippe Legros, "No, on the contrary, it confirmed our decision: given the context, the performance of Banque Populaire (second place) is remarkable: we have seen that (Armel Le Cléac'h and Erwan Tabarly, skippers) voluntarily sailed far more cautiously than other early in the race, which allowed them to be the only new boats to pass. Once the wind died down and the sea has row, they could use their foils, and from there, 40 miles behind, they moved ahead 35 Pot-au black. The boat, in this configuration, has impressive acceleration capabilities over time. This performance thus confirmed our studies and observations and I think if the race had taken place a year later, Banque Populaire, much more reliable, much would have happened to PRB. In view of the Vendée Globe, we had the choice between further optimize Maître CoQ by including new drift or move to foils, Jeremiah was clear on the subject: its goal is to win. Which is in our opinion not possible with only drifts. The differences in speed between the "foilers" and old boats can go up to 3 knots on a reach.

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There will be a point of diminishing returns with foils. There is drag inherent in generating lift and at some point the lift required to lift the boat higher will generate more drag than would be desirable.

Sure lift and drag are related, but as for the rest of your post:-

Why?

At what point?

Explain?

 

 

For extra points, please cite to Thursday's Child again in your explanation of foiling.

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There will be a point of diminishing returns with foils. There is drag inherent in generating lift and at some point the lift required to lift the boat higher will generate more drag than would be desirable.

Sure lift and drag are related, but as for the rest of your post:-

Why?

At what point?

Explain?

For extra points, please cite to Thursday's Child again in your explanation of foiling.

Oh boy, do I need to setup a new thread for this as well?

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Years of listening to multiple people with degrees in hydrodynamics explaining the basic principles of hydrodynamic lift and the resulting inherent drag or resistance. I am not able to quantify my answer I fear. Lars seemed to know something about it and we talked a lot on the subject. :wacko:

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Oh you are the clever one Clean. Trick question oh sagacious one. TC had no foils! Ha, you got me there you waskily wabbit. Maybe you could help a guy out? I know that there is a point at which the hydrodynamic coefficient combines with the frictional resistance to the resistance form. But what I cannot remember is the Reynolds number relationship. ?????

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Check out the pics on the next generation welded steel mast that SoH is being fitted out with.

 

http://spiritofhungary.hu/soh-60-madeira-megkezdodtek-a-szuksegarboc-es-vitorlazatanak-elkeszitesi-munkai/

 

 

 

Before you freak out, this is the temporary rig to take SoH home from Madeira.

 

Legend! Maybe when he gets the boat back, he can pass it on to Anasazi! :D

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Ref Post 1156.

 

Oh boy; that's why I love automatic google translation for technical stuff like sailing terms...

 

Replace "Pot-au-Black" by Doldrums. (Pot-au-noir in French; which litterally means Pot of Black... Don't ask me why)

Replace "drift" by dagger boards... And then it makes more sense....

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The below exceeds my translation ability, but is something I have always wondered. Can you explain?

 

which litterally means Pot of Black... Don't ask me why)

Replace "drift" by dagger boards... And then it makes more sense....

 

Voici d'ailleurs ce qu'on peut lire à propos de cet endroit :
« En cet endroit de l'océan règne une activité atmosphérique de surface exceptionnelle. Deux phénomènes en sont principalement à l'origine. La grande chaleur due à la proximité de l'équateur provoque une évaporation hors du commun. Les alizés nord et sud se rejoignent à cet endroit. La concentration de cumulo-nimbus y est donc plus forte qu'à n'importe quel autre endroit du globe. Si les vents dominants sont logiquement d'est, l'accumulation des gros nuages noirs souvent orageux annule et anarchise la circulation générale de l'air. Il en résulte, quand la zone est très active, une vaste zone de vents erratiques et évanescents qui font douter les marins sur leur capacité à pouvoir sortir de cet endroit. »

Il ne semble pas y avoir d'explication certaine sur l'origine de la dénomination de cette zone. Une chose est sûre, cela n'a rien à voir avec un poteau noir qui aurait découvert le poteau rose près du Potomac.
Ce qu'on sait, c'est qu'à la fin du XVIIe siècle, dans un jeu apparenté au colin-maillard, lorsque celui qui avait les yeux bandés risquait de se cogner dans quelque chose on lui lançait un "gare au pot au noir" d'avertissement, peut-être parce que, se cognant, il risquait de se faire un 'noir', autre nom de la bosse à l'époque.

Par extension, le pot au noir a désigné, à la fin du XIXe siècle, une situation embrouillée, dangereuse, caractéristique de ce qu'on peut trouver dans notre zone, qui aurait donc été nommée ainsi pour cette raison.
Cette appellation a été également utilisée par les aviateurs vers 1930 pour désigner une zone d'orages sans visibilité.

Exemple

« (…) lorsque Mermoz, pour la première fois, franchit l'Atlantique Sud en hydravion, il aborda, vers la tombée du jour, la région du Pot-au-Noir. Il vit, en face de lui, se resserrer, de minute en minute, les queues de tornades (…) puis la nuit s'établir (…) Et quand, une heure plus tard, il se faufila sous les nuages, il déboucha dans un royaume fantastique. »
Antoine de Saint-Exupéry - Terre des hommes

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Hey there court182...not listening ....thats COURT182 ....are you there son?

 

.....this is an excellent high level thread.....you simply don't belong here, and to put it bluntly you are just fucking it up for everyone.

 

So please go down the corridor to the door MAD built just for you.....or start your own thread. I'm sure Clean will give you a complementary coffee as OP and the authority to insult the intelligence of all as your heart desires...ultimately you may even want to swap out to a new mug

post-108919-0-92629000-1448467916_thumb.jpg

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Sorry, I must have missed the admissions test? What defines "High Level" anyway? Is there a course I may take so as to pass YOUR muster and access to the wonderfully high minded banter of Mr. Clean?

I kinda wanted to talk boats, did not realize I had to kiss rings to do so. What an egalitarian fellow you are!

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Nah, you can make it for the other people continuing this discussion. Or am I the only one who gets shit for contributing?

You contribute???

 

More like leaving a turd in the punch bowl.

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What, when you guys are just starting to make this fun?

How comforting it must be to know you have no equal. Oh, BTW, why is that important to you? Low self esteem perhaps, worrying whether or not someone is your "equal"? Were you, as I suspect Clean was, beaten much on the playground as a child?

Now, may I remain in your grand presence and observe or are only your "equals" allowed to do that as well? I promise to be good. Please????

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The below exceeds my translation ability, but is something I have always wondered. Can you explain?

 

which litterally means Pot of Black... Don't ask me why)

Replace "drift" by dagger boards... And then it makes more sense....

 

Voici d'ailleurs ce qu'on peut lire à propos de cet endroit :

« En cet endroit de l'océan règne une activité atmosphérique de surface exceptionnelle. Deux phénomènes en sont principalement à l'origine. La grande chaleur due à la proximité de l'équateur provoque une évaporation hors du commun. Les alizés nord et sud se rejoignent à cet endroit. La concentration de cumulo-nimbus y est donc plus forte qu'à n'importe quel autre endroit du globe. Si les vents dominants sont logiquement d'est, l'accumulation des gros nuages noirs souvent orageux annule et anarchise la circulation générale de l'air. Il en résulte, quand la zone est très active, une vaste zone de vents erratiques et évanescents qui font douter les marins sur leur capacité à pouvoir sortir de cet endroit. »

 

Il ne semble pas y avoir d'explication certaine sur l'origine de la dénomination de cette zone. Une chose est sûre, cela n'a rien à voir avec un poteau noir qui aurait découvert le poteau rose près du Potomac.

Ce qu'on sait, c'est qu'à la fin du XVIIe siècle, dans un jeu apparenté au colin-maillard, lorsque celui qui avait les yeux bandés risquait de se cogner dans quelque chose on lui lançait un "gare au pot au noir" d'avertissement, peut-être parce que, se cognant, il risquait de se faire un 'noir', autre nom de la bosse à l'époque.

 

Par extension, le pot au noir a désigné, à la fin du XIXe siècle, une situation embrouillée, dangereuse, caractéristique de ce qu'on peut trouver dans notre zone, qui aurait donc été nommée ainsi pour cette raison.

Cette appellation a été également utilisée par les aviateurs vers 1930 pour désigner une zone d'orages sans visibilité.

Exemple

« (…) lorsque Mermoz, pour la première fois, franchit l'Atlantique Sud en hydravion, il aborda, vers la tombée du jour, la région du Pot-au-Noir. Il vit, en face de lui, se resserrer, de minute en minute, les queues de tornades (…) puis la nuit s'établir (…) Et quand, une heure plus tard, il se faufila sous les nuages, il déboucha dans un royaume fantastique. »

Antoine de Saint-Exupéry - Terre des hommes

Ailleurs

 

Si vous souhaitez savoir comment on dit « Le pot au noir » en anglais, en espagnol, en portugais, en italien ou en allemand, cliquez ici

Ci-dessous vous trouverez des propositions de traduction soumises par notre communauté d’utilisateurs et non vérifiées par notre équipe. En étant enregistré, vous pourrez également en ajouter vous-même. En cas d’erreur, signalez-les nous dans le formulaire de contact

 

Too long to translate. Principal elements :

 

Colin-Maillard (Blind man's buff in English ?) : An ancient children’s game, played outdoors, in which a player who is blindfolded has to track down and recognize other (non blindfolded) players.

If the blindfolded player risks running into an obstacle (an object, a tree…), the other players yell to him « Gare au pot au noir » : « Beware of the black pot ». Or maybe black pole ?, it depends how you write it in French. What was really a black pot or a black pole, I have no idea.

 

But anyhow, the expression would refer to the notion of an unpleasant trap and colin-maillard, because the Doldrums is a place you enter blindfolded, not knowing which route to follow to get out of it.

 

The expression « Pot au noir » was really popularised by the French aviators pioneers of transatlantic and airmail flights between Africa and South America in the 1920’s (Mermoz, Saint-Exupéy, etc.).

 

Another long article in French in the V&V blog Route fond about the expression :

http://olivierchapuis.blogs.voilesetvoiliers.com/2013/02/15/histoires-de-pot-au-noir-33/

 

But on the Web, you can find other explications :

 

- It came from an ancient Portuguese expression from the first Portuguese sailors who crossed the Equator, meaning an inextricable situation.

 

- At the time of the slave trade, the Doldrums was an area where they threw overboard dead, sick or contagious slaves.

 

Pick yours, it seems nobody really knows the origin of Pot au noir.

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Hey there court182...not listening ....thats COURT182 ....are you there son?

 

.....this is an excellent high level thread.....you simply don't belong here, and to put it bluntly you are just fucking it up for everyone.

 

So please go down the corridor to the door MAD built just for you.....or start your own thread. I'm sure Clean will give you a complementary coffee as OP and the authority to insult the intelligence of all as your heart desires...ultimately you may even want to swap out to a new mug

don't flatter yourself, you're not much more than speculation from the wood work, he spews, you spew. that's how it works.

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Nah, you can make it for the other people continuing this discussion. Or am I the only one who gets shit for contributing?

You contribute???

 

More like leaving a turd in the punch bowl.

 

yea, you tell 'em, mr. righteous.

 

don't pretend this place is anything more than an orgy of gossip, with the rare bit of insight. why not just let others talk, as others tolerate it when you do? talk down to me like that, I'd call you a fuckin' cunt.

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