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      Abbreviated rules   07/28/2017

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DRIFTW00D

Boss Sinking?

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Whats up? Mast is not. Right sides not. Crew is, in Spanish chopper.

 

Dam just watched cleans walk arounds of the beast last night.

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Interesting latest update says the boat was rolled by a rogue wave while hove to - resulting in taking on a ton of water and "sustained damage" to the rig, hence the abandoned boat. The report goes on to say the wave while large should not have capsized the boat - no kidding. Wonder if its a case of cutting out too much lead and too high of a reliance on the foils.

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Interesting latest update says the boat was rolled by a rogue wave while hove to - resulting in taking on a ton of water and "sustained damage" to the rig, hence the abandoned boat. The report goes on to say the wave while large should not have capsized the boat - no kidding. Wonder if its a case of cutting out too much lead and too high of a reliance on the foils.

 

they seemed pretty confident that they would be able to recover the boat. I hope that they do and I'm very curious to see what's broken/how and what the designers and builders have to say about it

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Interesting latest update says the boat was rolled by a rogue wave while hove to - resulting in taking on a ton of water and "sustained damage" to the rig, hence the abandoned boat. The report goes on to say the wave while large should not have capsized the boat - no kidding. Wonder if its a case of cutting out too much lead and too high of a reliance on the foils.

 

they seemed pretty confident that they would be able to recover the boat. I hope that they do and I'm very curious to see what's broken/how and what the designers and builders have to say about it

 

 

I am sure they can recover it. The boat is not taking on water, the water that is in the boat came in the back hatch when it rolled, so with the hatch closed now, the situation should at least be "stable".

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Interesting latest update says the boat was rolled by a rogue wave while hove to - resulting in taking on a ton of water and "sustained damage" to the rig, hence the abandoned boat. The report goes on to say the wave while large should not have capsized the boat - no kidding. Wonder if its a case of cutting out too much lead and too high of a reliance on the foils.

 

they seemed pretty confident that they would be able to recover the boat. I hope that they do and I'm very curious to see what's broken/how and what the designers and builders have to say about it

 

 

I am sure they can recover it. The boat is not taking on water, the water that is in the boat came in the back hatch when it rolled, so with the hatch closed now, the situation should at least be "stable".

 

Why wouldn't they pump the bilge or bail it out before leaving it then? Much less damage would result, e.g to electrical and mechanical systems, if its not abandonned half full of seawater. Maybe it has hull damage right through the skin and is being kept afloat by watertight bulkheads and empty water ballast tanks?

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Wonder if its a case of cutting out too much lead and too high of a reliance on the foils.

.

AFAIK they have an OD keel, so no cutting in that case

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They must have had hull damage that allowed an ingress of water too severe to be just pumped out. With all the water sloshing around the boat becomes very unstable and can be rolled easier regardless of inherent stability. We know they had BIG issues way before the "capsize" jugging by the tracker, HB logged 3 kts for many hours they must have been trying to stabilize the situation. Definitely missing some big detail though.

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The boat looks like it's listing to starboard in the video. My guess is that the keel is canted over to keep the port side out of the water. If the foil on that side has been lost then there might be damage, so they might be trying to avoid further ingress.

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Video shows what looks like Alex to be the first to be airlifted out.. Could be me but ??something looks off .... Maybe other factors were in play...

 

Funny that you say that as that's what I was thinking as well.

 

I was once on a boat that we had to abandon late at night and the skipper was the first one off and I waited till all the crew were safe before I left the boat and I was rescued. It's called Duty of care and good seamanship.

 

It's very poor form I think for the skipper/ captain to be rescued first and leave the crew. What ever happened to the captan / skipper going down with the ship or being the last one rescued ?

 

I hope that it was the way it was edited that made it look this way that Alex was off first.

 

Pulpit

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Video shows what looks like Alex to be the first to be airlifted out.. Could be me but ??something looks off .... Maybe other factors were in play...

Funny that you say that as that's what I was thinking as well.

I was once on a boat that we had to abandon late at night and the skipper was the first one off and I waited till all the crew were safe before I left the boat and I was rescued. It's called Duty of care and good seamanship.

It's very poor form I think for the skipper/ captain to be rescued first and leave the crew. What ever happened to the captan / skipper going down with the ship or being the last one rescued ?

I hope that it was the way it was edited that made it look this way that Alex was off first.

Pulpit

That's just dumb. There are two people onboard. Both perfectly capable. Do you really think they gave 1 millisecond of thought to "you go first. No you go first." This isn't 18th century military. Stop trying to make something out of nothing. There are plenty of interesting details here. Who jumped first isn't one of them.

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uhm... I think before jumping to conclusions about what the captain did when, where and why, some of you armchair captains should wait for just some small bits of validated facts to come on the table before passing judgement. :mellow:

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I have been trying to understand what really went on on Hugo Boss, mainly because I remembered thinking the track was a bit odd for a boat retiring and seeking shelter for repairs. The boat turned totally about-face no less than 4 times before the crew were taken off. That is hardly normal. My first thought at the time was that they were just "hanging around", not wanting to reach port before their shore team were present to assist them in docking and to shield them from unwanted attention. Playing back the track on the tracker with the wind function working though, one can see the course changes look like just the response of a badly damaged boat to the weather conditions which must have been pretty unfriendly, with that new low forming so suddenly right by them. Reports from other nearby boats suggest that maximum wind speeds could possibly have been double what a grid based weather file would be indicating, and waves would have been "unusual" to say the least, with so many wind direction changes. After whatever it was that happened on the afternoon of the 28th, a classic case of being in the wrong place at the wrong time and with no way of predicting what was about to happen?

The timeline of their last couple of days, based on the official website tracker, was as below, with a simplified track shown from Universal Tracker.

28th, 1430 Boss track first becomes inconsistent with racing, boat turns to NorthEast, wind SW 25 kts. Boat continues going NE, N, and NE again with wind decreasing and veering to W, until, with wind W 16 kts :-

29th, 0530 boat turns to SE moving at around 5 to 6 kts, and continues on a ESE course turning gradually more Easterly and at about 8 kts, as wind backs towards South all in range 15 to 20 kts. Next abrupt change occurs at :-

30th, 1130 when boat turns 180 degrees when at about 100 miles from Spanish coast, and turns away from Spain and moves in direction just North of West at 4 to 5 knots as wind rather quickly increased to 25 - 30 kts from South. The wind then started decreasing and boat continued to move NNW until midnight, by when the wind had veered again to SW and decreased to 13 knots. Next abrupt change was:-

31st, 0005 Boat turns 180 degrees again and moves in direction ESE, at low speeds, (0 - 4 kts) as wind has decreased again (12 kts) and veered to SW, then WSW. Next event is at:-

31st, 0600 Wind veers from WSW to NNE and increases quickly from 12 knots to 24 knots and boat is gradually turning towards South at around 6 knots.

31st, 1030 wind still NNE, 22 kts, boat heading S at 6 kts and curving round gradually to SSW.

31st, 1215 wind veers right round to SSE and increases to between 30 and 35 knots. Boat turns to ENE at 5 knots. At this time a new local depression has just formed with centre 110 miles WNW from Cape Finistere and 50 miles WSW from the boat. At this time the boat was just 70 miles from the closest rias on the Spanish coast. Boat continues to move ENE for a further 20 miles until:-

31st, 2126 when website track ends with boat moving NNE at 1 knot in 25 knots of wind from ESE. Last position 80 miles from Spanish coast between Finistere and Coruna.

 

 

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I have been trying to understand what really went on on Hugo Boss, mainly because I remembered thinking the track was a bit odd for a boat retiring and seeking shelter for repairs. The boat turned totally about-face no less than 4 times before the crew were taken off. That is hardly normal. My first thought at the time was that they were just "hanging around", not wanting to reach port before their shore team were present to assist them in docking and to shield them from unwanted attention. Playing back the track on the tracker with the wind function working though, one can see the course changes look like just the response of a badly damaged boat to the weather conditions which must have been pretty unfriendly, with that new low forming so suddenly right by them. Reports from other nearby boats suggest that maximum wind speeds could possibly have been double what a grid based weather file would be indicating, and waves would have been "unusual" to say the least, with so many wind direction changes. After whatever it was that happened on the afternoon of the 28th, a classic case of being in the wrong place at the wrong time and with no way of predicting what was about to happen?

The timeline of their last couple of days, based on the official website tracker, was as below, with a simplified track shown from Universal Tracker.

28th, 1430 Boss track first becomes inconsistent with racing, boat turns to NorthEast, wind SW 25 kts. Boat continues going NE, N, and NE again with wind decreasing and veering to W, until, with wind W 16 kts :-

29th, 0530 boat turns to SE moving at around 5 to 6 kts, and continues on a ESE course turning gradually more Easterly and at about 8 kts, as wind backs towards South all in range 15 to 20 kts. Next abrupt change occurs at :-

30th, 1130 when boat turns 180 degrees when at about 100 miles from Spanish coast, and turns away from Spain and moves in direction just North of West at 4 to 5 knots as wind rather quickly increased to 25 - 30 kts from South. The wind then started decreasing and boat continued to move NNW until midnight, by when the wind had veered again to SW and decreased to 13 knots. Next abrupt change was:-

31st, 0005 Boat turns 180 degrees again and moves in direction ESE, at low speeds, (0 - 4 kts) as wind has decreased again (12 kts) and veered to SW, then WSW. Next event is at:-

31st, 0600 Wind veers from WSW to NNE and increases quickly from 12 knots to 24 knots and boat is gradually turning towards South at around 6 knots.

31st, 1030 wind still NNE, 22 kts, boat heading S at 6 kts and curving round gradually to SSW.

31st, 1215 wind veers right round to SSE and increases to between 30 and 35 knots. Boat turns to ENE at 5 knots. At this time a new local depression has just formed with centre 110 miles WNW from Cape Finistere and 50 miles WSW from the boat. At this time the boat was just 70 miles from the closest rias on the Spanish coast. Boat continues to move ENE for a further 20 miles until:-

31st, 2126 when website track ends with boat moving NNE at 1 knot in 25 knots of wind from ESE. Last position 80 miles from Spanish coast between Finistere and Coruna.

 

post-35226-0-85431300-1446382028_thumb.jpg

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uhm... I think before jumping to conclusions about what the captain did when, where and why, some of you armchair captains should wait for just some small bits of validated facts to come on the table before passing judgement. :mellow:

But this is SA, we don't deal in validated facts round here.

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Video shows what looks like Alex to be the first to be airlifted out.. Could be me but ??something looks off .... Maybe other factors were in play...

 

Yes, there could've been a mutiny too?

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Video shows what looks like Alex to be the first to be airlifted out.. Could be me but ??something looks off .... Maybe other factors were in play...

Funny that you say that as that's what I was thinking as well.

I was once on a boat that we had to abandon late at night and the skipper was the first one off and I waited till all the crew were safe before I left the boat and I was rescued. It's called Duty of care and good seamanship.

It's very poor form I think for the skipper/ captain to be rescued first and leave the crew. What ever happened to the captan / skipper going down with the ship or being the last one rescued ?

I hope that it was the way it was edited that made it look this way that Alex was off first.

Pulpit

That's just dumb. There are two people onboard. Both perfectly capable. Do you really think they gave 1 millisecond of thought to "you go first. No you go first." This isn't 18th century military. Stop trying to make something out of nothing. There are plenty of interesting details here. Who jumped first isn't one of them.

 

 

Don't you think BMW and Pulpit that in such an Helivac run by Spanish coast-guards it would be clever to have the spanish-speaking member of the crew stay on the boat with the hand-held VHF (hard to hear with the helo noise), while the non spanish-speaking skipper goes first ?

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Dumb question department:

 

I know fuck all about sailing a boat with a canting keel, or encountering 'rogue waves' for that matter - but why would the keel be canted while she was hove-to? That doesn't make any sense to me at all. Wouldn't locking it amidships be the sensible and prudent thing?

 

Could this more about a boat handling error under the circumstances described?

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Video shows what looks like Alex to be the first to be airlifted out.. Could be me but ??something looks off .... Maybe other factors were in play...

Funny that you say that as that's what I was thinking as well.

I was once on a boat that we had to abandon late at night and the skipper was the first one off and I waited till all the crew were safe before I left the boat and I was rescued. It's called Duty of care and good seamanship.

It's very poor form I think for the skipper/ captain to be rescued first and leave the crew. What ever happened to the captan / skipper going down with the ship or being the last one rescued ?

I hope that it was the way it was edited that made it look this way that Alex was off first.

Pulpit

That's just dumb. There are two people onboard. Both perfectly capable. Do you really think they gave 1 millisecond of thought to "you go first. No you go first." This isn't 18th century military. Stop trying to make something out of nothing. There are plenty of interesting details here. Who jumped first isn't one of them.

 

 

Don't you think BMW and Pulpit that in such an Helivac run by Spanish coast-guards it would be clever to have the spanish-speaking member of the crew stay on the boat with the hand-held VHF (hard to hear with the helo noise), while the non spanish-speaking skipper goes first ?

 

 

That is the best possible answer for the pretty lame act, historically and nowadays, to the essential rule that the skipper leaves a sinking ship last. Maybe he wanted to be first off so he could be first back to recover the boat.. :-)

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Dumb question department:

 

I know fuck all about sailing a boat with a canting keel, or encountering 'rogue waves' for that matter - but why would the keel be canted while she was hove-to? That doesn't make any sense to me at all. Wouldn't locking it amidships be the sensible and prudent thing?

 

Could this more about a boat handling error under the circumstances described?

The keel would (probably) have been locked midships when hove to, but that is what makes the boat stable when upside down. Moving the keel to one side when upside down starts tipping the boat to the point where the keel weight is far enough to one side to make the boat turn right side up.

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Dumb question department:

 

I know fuck all about sailing a boat with a canting keel, or encountering 'rogue waves' for that matter - but why would the keel be canted while she was hove-to? That doesn't make any sense to me at all. Wouldn't locking it amidships be the sensible and prudent thing?

 

Could this more about a boat handling error under the circumstances described?

The keel would (probably) have been locked midships when hove to, but that is what makes the boat stable when upside down. Moving the keel to one side when upside down starts tipping the boat to the point where the keel weight is far enough to one side to make the boat turn right side up.

That makes sense. Thanks, staysail.

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.......maybe they wanted more on ocean coverage for their sponsor?

 

......In the world of publicity ,this is considered as 'good' :mellow:

 

 

 

 

......''I am now going to go with the technical team and ensure a successful recovery of our new racing yacht.''

. .......sounds like a very polite way to say he's VERY pissed off :mellow:

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You have a shiny new boat, did the prudent thing and routed around the bad weather in order to keep it together while still doing the race.

Then it starts to fall apart. Probably not in a place where HB made "extreme" design choices over the others, or he would not be so cocky. You have to chill 2 days hove to in bad weather because of the damage. Then the whole thing falls apart and you get lifted off.

Now you ask yourself if you should have, or even could have, turned on the engine in order to skip the sinking part. Or ordered a tug? Many expensive options, both in money and reputation, become real cheap in retrospective.

 

The boat is mostly bust, no way to test more. Rebuild will take time.

Oh, given the timeline right about now you have to make a decision: Keep the mustache or not.

That the others broke in various places, but BP8 so far did not does not help either.

 

Yeah, Alex is not a happy camper right now.

 

 

 

And guys, at least link the official video, not the ripoff.

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Besides all: The guys in the Heli are completely nuts, especially the one who goes down. I mean one false move of the pilot and your done splashing against the boat instead into the water.

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This time I do not think breakage can be laid at AT's feet. I just watched the onboard interview, believing it included a boat tour, as i wanted to see rib layout, etc... Noticed a by now ironic quote from AT, while discussing how close cockpit floor is to waterline, "If we're hove to in the Southern Ocean, we'll keep the doors closed." Easy to armchair quarterback here, but folks, when in doubt-put the hatch boards in.

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Another update:

 

AT and crew onboard--HB not sunk

 

http://www.alexthomsonracing.com/update-2/

ALEX THOMSON RACING Update

 

01 Nov 2015 by sarah

Alex Thomson and his team are onboard HUGO BOSS which is now in a stable situation. Alex’s IMOCA 60 is undergoing the necessary checks in order to tow her back to A Coruna, Spain. Where additional team members are on hand to assist with the pending arrival. The rig has been removed and the water onboard pumped out, allowing the racing yacht to be towed. The weather conditions have enabled Alex Thomson Racing to complete a swift response to the emergency situation which occurred yesterday. The yacht is currently situated 100 miles offshore. The crew will remain onboard to make the necessary checks to ensure a safe tow through the night.

Technical Director Ross Daniel says ‘I am proud of our team considering the potential severity of the situation. Of course it’s disappointing we have had to retire from the race. But this year’s Transat Jacques Vabre has provided the fleet with challenging conditions, forcing seven IMOCA’s to retire. As a team we now need to focus on getting HUGO BOSS safely through the night and then assess the situation once she is alongside tomorrow.’

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Good morning couch you are 8h behind the news. ;)

 

The salvage team reached HB 12 ago, cleared the mast and started to dewater 9h ago. Last news was that damage checks follow after that, then tow back to shore. Possibly some put in additional stabilization too now that they are no longer limited to race rules.

 

It's midnight now, so more news in a few hours aka Monday morning. Hopefully from shore.

Best source for details so far, other than Mr.Clean of course, has been this twittter account.

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Good morning couch you are 8h behind the news. ;)

 

The salvage team reached HB 12 ago, cleared the mast and started to dewater 9h ago. Last news was that damage checks follow after that, then tow back to shore. Possibly some put in additional stabilization too now that they are no longer limited to race rules.

 

It's midnight now, so more news in a few hours aka Monday morning. Hopefully from shore.

Best source for details so far, other than Mr.Clean of course, has been this twittter account.

.

 

...thanks for that,,I guess Clean is too. I posted earlier,,,but for some stwange reason elements seem to be getting -edited- from my posts :wacko: ..........time for my tinfoil hat :mellow:

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[snip] I posted earlier,,,but for some stwange reason elements seem to be getting -edited- from my posts :wacko: ..........time for my tinfoil hat :mellow:

 

Hey Couch. FWIW, I recall seeing your repost of Clean's interview in this thread a few hours ago, so you didn't imagine posting.

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[snip] I posted earlier,,,but for some stwange reason elements seem to be getting -edited- from my posts :wacko: ..........time for my tinfoil hat :mellow:

 

Hey Couch. FWIW, I recall seeing your repost of Clean's interview in this thread a few hours ago, so you didn't imagine posting.

 

.

 

 

........STWANGE. vewwy. stwange. :mellow: whatever :unsure:

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I think by canting the keel it puts the boat on its chine which reduces the rocking back and forth on the waves. They also might have had some damage to the trunk for the J board and were trying to keep it out of the water.

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I think by canting the keel it puts the boat on its chine which reduces the rocking back and forth on the waves. They also might have had some damage to the trunk for the J board and were trying to keep it out of the water.

If any of that is factual, it wouldn't have taken much of a 'rogue wave' to do the damage. Just sayin.

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You have a shiny new boat, did the prudent thing and routed around the bad weather in order to keep it together while still doing the race.

Then it starts to fall apart. Probably not in a place where HB made "extreme" design choices over the others, or he would not be so cocky. You have to chill 2 days hove to in bad weather because of the damage. Then the whole thing falls apart and you get lifted off.

Now you ask yourself if you should have, or even could have, turned on the engine in order to skip the sinking part. Or ordered a tug? Many expensive options, both in money and reputation, become real cheap in retrospective.

 

The boat is mostly bust, no way to test more. Rebuild will take time.

Oh, given the timeline right about now you have to make a decision: Keep the mustache or not.

That the others broke in various places, but BP8 so far did not does not help either.

 

Yeah, Alex is not a happy camper right now.

 

 

 

And guys, at least link the official video, not the ripoff.

 

unbroken BP and 4 others broken I think will leave many both crews, designers and builders scratching their heads. I agree that this can't just be laid at AT's feet but I also don't think that the breakages can be blamed on the j-foils either. from what I've read the past few days it sounds like the problems lie more in the hull construction than anything else.

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Was this super light hull construction necessary to make the lifting foils effective? They upped the minimum required weight from thethe previous generation, correct?

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Are we SURE BP isn't broken?? Have they managed to avoid the big WAVES that have caused damage to the other boats???

Well...put it this way - creaming along at 16.5 knots in a 15 knot breeze suggest she ain't broke yet. Long may it continue.

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A possible advantage to the skin and rib construction is that it may be stiffer. With the right mix of curve and rib support, and a skin strong enough that it doesn't oilcan when slamming, you will have a very stiff hull. Possibly stiffer than a dual skin on core construction. Stiffer hulls are faster. So the attraction may be there.

 

Carbon is funny stuff, and I would hesitate to say the above is in any way true - but the quest for speed drives things in interesting directions.

 

The reality is also that stiff usually means brittle and a 3D structure built from carbon (ie the rib bonded to the skin) is a very difficult thing to analyse. Basically you are making a 3D structure from 1D fibres that are silly strong along their length, and have a huge modulus, but also much stronger than the adhesive that bonds them in the other two directions. It is very difficult to predict how such a structure will fail, as it has a large number of degrees of freedom, and the brittleness of the material, and nasty habit of catastrophic failure without warning, means that you have a very hard time coming up with meaningful predictions and rules.

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A possible advantage to the skin and rib construction is that it may be stiffer. With the right mix of curve and rib support, and a skin strong enough that it doesn't oilcan when slamming, you will have a very stiff hull. Possibly stiffer than a dual skin on core construction. Stiffer hulls are faster. So the attraction may be there.

 

Carbon is funny stuff, and I would hesitate to say the above is in any way true - but the quest for speed drives things in interesting directions.

 

The reality is also that stiff usually means brittle and a 3D structure built from carbon (ie the rib bonded to the skin) is a very difficult thing to analyse. Basically you are making a 3D structure from 1D fibres that are silly strong along their length, and have a huge modulus, but also much stronger than the adhesive that bonds them in the other two directions. It is very difficult to predict how such a structure will fail, as it has a large number of degrees of freedom, and the brittleness of the material, and nasty habit of catastrophic failure without warning, means that you have a very hard time coming up with meaningful predictions and rules.

 

 

 

I also remember that a few months ago AT Racing announced with some fanfare that they were playing with ultra-thin graphene. I wonder if this actually made it into any of the final design of the boat?

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Whoever added the soundtrack to the video is a massive fuckwit.

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A possible advantage to the skin and rib construction is that it may be stiffer. With the right mix of curve and rib support, and a skin strong enough that it doesn't oilcan when slamming, you will have a very stiff hull. Possibly stiffer than a dual skin on core construction. Stiffer hulls are faster. So the attraction may be there.

 

Carbon is funny stuff, and I would hesitate to say the above is in any way true - but the quest for speed drives things in interesting directions.

 

The reality is also that stiff usually means brittle and a 3D structure built from carbon (ie the rib bonded to the skin) is a very difficult thing to analyse. Basically you are making a 3D structure from 1D fibres that are silly strong along their length, and have a huge modulus, but also much stronger than the adhesive that bonds them in the other two directions. It is very difficult to predict how such a structure will fail, as it has a large number of degrees of freedom, and the brittleness of the material, and nasty habit of catastrophic failure without warning, means that you have a very hard time coming up with meaningful predictions and rules.

Maybe I am a bit simple but for me when thinking about composite structures, words like "modulus", "stiff", "strong", "brittle", ("oilcan?") have questionable meanings unless they are applied to a specific item or a specific set of material combinations and design and construction details and qualified by very precise sets of explanations. I would be interested if you can explain in engineering terms, just why, for a given weight, you think a skin and rib construction would be "stiffer" than a cored double skin structure?

 

Also what do you mean by, "the right mix of curve and rib support", and "large number of degrees of freedom", as applied to a composite structure? What is a large number? small number?

 

Also, while I understand it is a commonly held view, can you explain in simple engineering or mathematical language, why, all other things being equal, "stiffer hulls are faster"?

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A possible advantage to the skin and rib construction is that it may be stiffer. With the right mix of curve and rib support, and a skin strong enough that it doesn't oilcan when slamming, you will have a very stiff hull. Possibly stiffer than a dual skin on core construction. Stiffer hulls are faster. So the attraction may be there.

 

Carbon is funny stuff, and I would hesitate to say the above is in any way true - but the quest for speed drives things in interesting directions.

 

The reality is also that stiff usually means brittle and a 3D structure built from carbon (ie the rib bonded to the skin) is a very difficult thing to analyse. Basically you are making a 3D structure from 1D fibres that are silly strong along their length, and have a huge modulus, but also much stronger than the adhesive that bonds them in the other two directions. It is very difficult to predict how such a structure will fail, as it has a large number of degrees of freedom, and the brittleness of the material, and nasty habit of catastrophic failure without warning, means that you have a very hard time coming up with meaningful predictions and rules.

Maybe I am a bit simple but for me when thinking about composite structures, words like "modulus", "stiff", "strong", "brittle", ("oilcan?") have questionable meanings unless they are applied to a specific item or a specific set of material combinations and design and construction details and qualified by very precise sets of explanations. I would be interested if you can explain in engineering terms, just why, for a given weight, you think a skin and rib construction would be "stiffer" than a cored double skin structure?

 

Also what do you mean by, "the right mix of curve and rib support", and "large number of degrees of freedom", as applied to a composite structure? What is a large number? small number?

 

Also, while I understand it is a commonly held view, can you explain in simple engineering or mathematical language, why, all other things being equal, "stiffer hulls are faster"?

 

 

Stiffer hulls are faster because they are the main structural element of the rig .. with the mast pushing down in the middle and the stays pulling up the ends a soft hull prevents the rigging from being tensioned to the degree that modern sailors like.

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So if you are hove too in an imoca 60 do you go foils up or down? Perhaps down to try to dampen motion, but then maybe that could trip the boat over more if it got hit by a rouge wave from the side?

 

Would the moustache fouls change this ?

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A possible advantage to the skin and rib construction is that it may be stiffer. With the right mix of curve and rib support, and a skin strong enough that it doesn't oilcan when slamming, you will have a very stiff hull. Possibly stiffer than a dual skin on core construction. Stiffer hulls are faster. So the attraction may be there.

 

Carbon is funny stuff, and I would hesitate to say the above is in any way true - but the quest for speed drives things in interesting directions.

 

The reality is also that stiff usually means brittle and a 3D structure built from carbon (ie the rib bonded to the skin) is a very difficult thing to analyse. Basically you are making a 3D structure from 1D fibres that are silly strong along their length, and have a huge modulus, but also much stronger than the adhesive that bonds them in the other two directions. It is very difficult to predict how such a structure will fail, as it has a large number of degrees of freedom, and the brittleness of the material, and nasty habit of catastrophic failure without warning, means that you have a very hard time coming up with meaningful predictions and rules.

Maybe I am a bit simple but for me when thinking about composite structures, words like "modulus", "stiff", "strong", "brittle", ("oilcan?") have questionable meanings unless they are applied to a specific item or a specific set of material combinations and design and construction details and qualified by very precise sets of explanations. I would be interested if you can explain in engineering terms, just why, for a given weight, you think a skin and rib construction would be "stiffer" than a cored double skin structure?

 

Also what do you mean by, "the right mix of curve and rib support", and "large number of degrees of freedom", as applied to a composite structure? What is a large number? small number?

 

Also, while I understand it is a commonly held view, can you explain in simple engineering or mathematical language, why, all other things being equal, "stiffer hulls are faster"?

 

 

I was mostly thinking in terms of the flexibility of the hull. A convex carbon shell of say 3mm thickness may well flex less in response to slamming and waves than a thinner skin on honeycomb next to an inner skin. Mostly because the core itself will flex to come extent. OTOH we see some IMOCA boats built on aluminium honeycomb. (Not always with happy results.) My base assumption has been that hulls flexing in waves are dissipating energy. The obvious analogue being higher tire pressure yielding lower rolling resistance. Overall the thought is that there is no core material - be it aluminium, Nomex, or foam, forming part of the structure. Core materials compress in response to stress on the hull structure and the entire structure's stiffness is limited by this. A structure that is a single convex hull (hull in the mathematical sense as well as nautical) will have an intrinsic stiffness that is dependant upon the modulus of the hull skin, and not limited by a core material. Whether this is actually true in practice, I don't know.

 

The point about the right mix of ribs and curvature is simply that the hull is a convex structure. Some bits more convex than other, but convex it is. Intrinsically it will resist deformation, but those areas where the hull is flatter, or subject to greater load will need greater support. So the design balances the loads, the intrinsic curvature of the skin, and the rib distribution, to we hope best effect. Where it starts to become a problem is with larger unsupported areas that are not very convex, and a load will cause them to "oilcan". Once that is happening the design has failed to meet its goals.

 

The point about many degrees of freedom is about failure of composites. Composites are not isotropic. You have a 3D structure, probably hollow, that is itself made up of layers of unidirectional or woven fibre. The direction of fibres varies with the depth of the layup. But it is a layered material. Fibres do not transit between layers. The overall structure has a range of movements in response to stress, but the internal fibres can and will behave in response in a non-isotropic manner. In particular the layup adhesive can fail. So any analysis that seeks to determine failure of the structure is not dealing with an isotropic material, but one that internally can fail in difficult to predict ways. The additional degrees of freedom in the system are essentially those that come about because of the non-isotropic nature of the material. There are software design tools that try to predict this, but whether they are used in the boat design, or even affordable by the designers, is another matter.

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A possible advantage to the skin and rib construction is that it may be stiffer. With the right mix of curve and rib support, and a skin strong enough that it doesn't oilcan when slamming, you will have a very stiff hull. Possibly stiffer than a dual skin on core construction. Stiffer hulls are faster. So the attraction may be there.

 

Carbon is funny stuff, and I would hesitate to say the above is in any way true - but the quest for speed drives things in interesting directions.

 

The reality is also that stiff usually means brittle and a 3D structure built from carbon (ie the rib bonded to the skin) is a very difficult thing to analyse. Basically you are making a 3D structure from 1D fibres that are silly strong along their length, and have a huge modulus, but also much stronger than the adhesive that bonds them in the other two directions. It is very difficult to predict how such a structure will fail, as it has a large number of degrees of freedom, and the brittleness of the material, and nasty habit of catastrophic failure without warning, means that you have a very hard time coming up with meaningful predictions and rules.

Maybe I am a bit simple but for me when thinking about composite structures, words like "modulus", "stiff", "strong", "brittle", ("oilcan?") have questionable meanings unless they are applied to a specific item or a specific set of material combinations and design and construction details and qualified by very precise sets of explanations. I would be interested if you can explain in engineering terms, just why, for a given weight, you think a skin and rib construction would be "stiffer" than a cored double skin structure?

 

Also what do you mean by, "the right mix of curve and rib support", and "large number of degrees of freedom", as applied to a composite structure? What is a large number? small number?

 

Also, while I understand it is a commonly held view, can you explain in simple engineering or mathematical language, why, all other things being equal, "stiffer hulls are faster"?

 

 

Stiffer hulls are faster because they are the main structural element of the rig .. with the mast pushing down in the middle and the stays pulling up the ends a soft hull prevents the rigging from being tensioned to the degree that modern sailors like.

 

I did say "other things being equal" by which I included rig tension. You have two different hulls of the same unstressed shape and the same weight and moments of inertia. One is twice as stiff as the other, i.e. both can be elastically deflected by rigging stress but one of them deflects twice as much as the other when subjected to the same rigging tensions. i.e. one hull is twice as stiff as the other.

Is the stiffer boat faster? If so, why?

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^ :) This is starting to get into one of those "Is fitting a cunningham eye on my main worthwhile?" sorta threads, methinks!

.

 

 

. ....do you think that would help? :mellow:

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according to AT's page

Whilst waiting for the weather to clear a rogue wave caught HUGO BOSS causing the yacht to turn upside down. Alex and Guillermo managed to close the hatches and secure the situation whilst inverted. Alex immediately hit the keel button, bringing the IMOCA back upright.

 

AFAIK this is the first time an IMOCA has actually been righted from a capsize (outside of the silly test) by flicking the keel, am I right? Has AT or Altadil confirmed that the boat was rolled all the way over?

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Stiffer hulls are faster because they are the main structural element of the rig .. with the mast pushing down in the middle and the stays pulling up the ends a soft hull prevents the rigging from being tensioned to the degree that modern sailors like.

 

 

I did say "other things being equal" by which I included rig tension. You have two different hulls of the same unstressed shape and the same weight and moments of inertia. One is twice as stiff as the other, i.e. both can be elastically deflected by rigging stress but one of them deflects twice as much as the other when subjected to the same rigging tensions. i.e. one hull is twice as stiff as the other.

Is the stiffer boat faster? If so, why?

 

 

 

While definitely not generally true (in finn hulls for example they deliberately keep a section of the hull soft so it can change it's shape when slamming on waves), in most cases stiffer hulls will be faster:

 

firstly: as Terry Hollis said, a stiffer hull allows for more rig tension. So all other things being equal (including mast and all stay lengths) the stiffer hull will deflect less due to the rig tension, hence the rig tension will increase ;)

Add to this the increased possibility to trim (tighten) the rig and you get an aerodynamically more efficient sail plan (with a soft hull at some point you can shorten the says, but it will no longer increase the tension in the stays).

 

Even if you want to keep the base rig tension equal between the stiffer and the weaker hull (hence changing the rig/increasing the stay lengths on the stiffer hull) the stiffer hull will still lead to improved aerodynamical performance of the sails as in real life conditions.

To illustrate this you can look at a significant slam due to ocean waves: the slam will lead to an upward pointing force/moment, deflecting the bow section upwards. As this force is (approximately) independent of the hull stiffness, this force will lead to a higher deflection in the weaker hull compared to the stiffer hull. Hence it will lead to more temporary sag in the forestay for the weaker hull. Hence the sail shape of a stiffer hull is fluctuating less over time, which is generally what you want if you want to go fast ;).

 

Secondly all deformation takes energy (work = force * deflection). And if you want to go fast you would prefer this energy to go into forward propulsion instead of deflecting anything structural...

take again the above example of the slam and fill in this equation. As you can see the force stays the same while the deflection increases for the weaker hull. Hence the work taken for deflecting the hull is (approximately, when simplified to the extreme) proportional to the amount of deflection in the hull. Hence the stiffer the hull the less energy is wasted in the deflection of the hull!

 

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The point about many degrees of freedom is about failure of composites. Composites are not isotropic. You have a 3D structure, probably hollow, that is itself made up of layers of unidirectional or woven fibre. The direction of fibres varies with the depth of the layup. But it is a layered material. Fibres do not transit between layers. The overall structure has a range of movements in response to stress, but the internal fibres can and will behave in response in a non-isotropic manner. In particular the layup adhesive can fail. So any analysis that seeks to determine failure of the structure is not dealing with an isotropic material, but one that internally can fail in difficult to predict ways. The additional degrees of freedom in the system are essentially those that come about because of the non-isotropic nature of the material. There are software design tools that try to predict this, but whether they are used in the boat design, or even affordable by the designers, is another matter.

 

Thanks for this, Francis. I was wondering about this when laying up my rudder (albeit in much less sophisticated terms and terminology). I used a glass tie-layer to a naca foil made of foam, and then up to 72 ounces of cloth weight in carbon fiber uni and twill. By the time I got the last layer on, I was thinking in my dim brain: with all the [anisotropic] properties of this thing, it's doomed :-)

 

Glad to see the Boss is back.

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according to AT's page

Whilst waiting for the weather to clear a rogue wave caught HUGO BOSS causing the yacht to turn upside down. Alex and Guillermo managed to close the hatches and secure the situation whilst inverted. Alex immediately hit the keel button, bringing the IMOCA back upright.

 

AFAIK this is the first time an IMOCA has actually been righted from a capsize (outside of the silly test) by flicking the keel, am I right? Has AT or Altadil confirmed that the boat was rolled all the way over?

you did read that they had to tip the keel to the other side, right?

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Stiffer hulls are faster because they are the main structural element of the rig .. with the mast pushing down in the middle and the stays pulling up the ends a soft hull prevents the rigging from being tensioned to the degree that modern sailors like.

 

 

I did say "other things being equal" by which I included rig tension. You have two different hulls of the same unstressed shape and the same weight and moments of inertia. One is twice as stiff as the other, i.e. both can be elastically deflected by rigging stress but one of them deflects twice as much as the other when subjected to the same rigging tensions. i.e. one hull is twice as stiff as the other.

Is the stiffer boat faster? If so, why?

 

 

 

While definitely not generally true (in finn hulls for example they deliberately keep a section of the hull soft so it can change it's shape when slamming on waves), in most cases stiffer hulls will be faster:

 

firstly: as Terry Hollis said, a stiffer hull allows for more rig tension. So all other things being equal (including mast and all stay lengths) the stiffer hull will deflect less due to the rig tension, hence the rig tension will increase ;)

Add to this the increased possibility to trim (tighten) the rig and you get an aerodynamically more efficient sail plan (with a soft hull at some point you can shorten the says, but it will no longer increase the tension in the stays).

 

Even if you want to keep the base rig tension equal between the stiffer and the weaker hull (hence changing the rig/increasing the stay lengths on the stiffer hull) the stiffer hull will still lead to improved aerodynamical performance of the sails as in real life conditions.

To illustrate this you can look at a significant slam due to ocean waves: the slam will lead to an upward pointing force/moment, deflecting the bow section upwards. As this force is (approximately) independent of the hull stiffness, this force will lead to a higher deflection in the weaker hull compared to the stiffer hull. Hence it will lead to more temporary sag in the forestay for the weaker hull. Hence the sail shape of a stiffer hull is fluctuating less over time, which is generally what you want if you want to go fast ;).

 

Secondly all deformation takes energy (work = force * deflection). And if you want to go fast you would prefer this energy to go into forward propulsion instead of deflecting anything structural...

take again the above example of the slam and fill in this equation. As you can see the force stays the same while the deflection increases for the weaker hull. Hence the work taken for deflecting the hull is (approximately, when simplified to the extreme) proportional to the amount of deflection in the hull. Hence the stiffer the hull the less energy is wasted in the deflection of the hull!

 

 

That's what i thought:" deformation takes energy (work = force * deflection).". I can speak about sailboards, and stiffer faster, although your knees suffer more.

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Stiffer hulls are faster because they are the main structural element of the rig .. with the mast pushing down in the middle and the stays pulling up the ends a soft hull prevents the rigging from being tensioned to the degree that modern sailors like.

 

 

I did say "other things being equal" by which I included rig tension. You have two different hulls of the same unstressed shape and the same weight and moments of inertia. One is twice as stiff as the other, i.e. both can be elastically deflected by rigging stress but one of them deflects twice as much as the other when subjected to the same rigging tensions. i.e. one hull is twice as stiff as the other.

Is the stiffer boat faster? If so, why?

 

 

 

While definitely not generally true (in finn hulls for example they deliberately keep a section of the hull soft so it can change it's shape when slamming on waves), in most cases stiffer hulls will be faster:

 

firstly: as Terry Hollis said, a stiffer hull allows for more rig tension. So all other things being equal (including mast and all stay lengths) the stiffer hull will deflect less due to the rig tension, hence the rig tension will increase ;)

Add to this the increased possibility to trim (tighten) the rig and you get an aerodynamically more efficient sail plan (with a soft hull at some point you can shorten the says, but it will no longer increase the tension in the stays).

 

Even if you want to keep the base rig tension equal between the stiffer and the weaker hull (hence changing the rig/increasing the stay lengths on the stiffer hull) the stiffer hull will still lead to improved aerodynamical performance of the sails as in real life conditions.

To illustrate this you can look at a significant slam due to ocean waves: the slam will lead to an upward pointing force/moment, deflecting the bow section upwards. As this force is (approximately) independent of the hull stiffness, this force will lead to a higher deflection in the weaker hull compared to the stiffer hull. Hence it will lead to more temporary sag in the forestay for the weaker hull. Hence the sail shape of a stiffer hull is fluctuating less over time, which is generally what you want if you want to go fast ;).

 

Secondly all deformation takes energy (work = force * deflection). And if you want to go fast you would prefer this energy to go into forward propulsion instead of deflecting anything structural...

take again the above example of the slam and fill in this equation. As you can see the force stays the same while the deflection increases for the weaker hull. Hence the work taken for deflecting the hull is (approximately, when simplified to the extreme) proportional to the amount of deflection in the hull. Hence the stiffer the hull the less energy is wasted in the deflection of the hull!

 

 

That's what i thought:" deformation takes energy (work = force * deflection).". I can speak about sailboards, and stiffer faster, although your knees suffer more.

 

Speaking of sailboards, some nice speedruns in Namibia. Should deserve it's own topic

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Spoke to Alex an hour ago. In good spirits with the boat alongside in Spain. He will get a few hours sleep and then we will talk, and he agreed to do it via video skype so I can record it straight to the laptop and get it up quickly.

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I Know apples and oranges. Still this gives a scaled up view of what the Current VPLP boats look like in construction. Look at all the bits and pieces to be bonded in. And the rib to skin construction in the vedio gives an idea of the latest Boss boats hull.

 

 

First Look : VPLP 100 Comanche - Sailing Anarchy

from Penalty Box Productions PLUS 1 year ago / Creative Commons License: by sa NOT YET RATED

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Looks like Boss made it safely back to the dock.

That's good news.

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Good news, but looking like a challenging time frame to be on the start line AND competitive for the vendee.

 

Need to work out how to implement a robust fix, implement it and work the boat upto speed including ironing out minor failings. HB were the last to launch and had a years programme to get the boat competitive. They must have lost at least 6 months of that.

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according to AT's page

Whilst waiting for the weather to clear a rogue wave caught HUGO BOSS causing the yacht to turn upside down. Alex and Guillermo managed to close the hatches and secure the situation whilst inverted. Alex immediately hit the keel button, bringing the IMOCA back upright.

 

AFAIK this is the first time an IMOCA has actually been righted from a capsize (outside of the silly test) by flicking the keel, am I right? Has AT or Altadil confirmed that the boat was rolled all the way over?

you did read that they had to tip the keel to the other side, right?

 

What we read was, AT managed..."to hit the keel button".

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I Know apples and oranges. Still this gives a scaled up view of what the Current VPLP boats look like in construction. Look at all the bits and pieces to be bonded in. And the rib to skin construction in the vedio gives an idea of the latest Boss boats hull.

 

 

First Look : VPLP 100 Comanche - Sailing Anarchy

from Penalty Box Productions PLUS 1 year ago / Creative Commons License: by sa NOT YET RATED

Similar, but the ribs are oriented differently. Am working on getting my video inside Boss up but it is pretty fucked.

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Spoke to Alex an hour ago. In good spirits with the boat alongside in Spain. He will get a few hours sleep and then we will talk, and he agreed to do it via video skype so I can record it straight to the laptop and get it up quickly.

Al, since everybody here (well most of 'em :-) have been clambering over each other to get onto their soap boxes, would be good to hear, blow by blow, what really went down from the moment they knew things were going tits up.

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according to AT's page

Whilst waiting for the weather to clear a rogue wave caught HUGO BOSS causing the yacht to turn upside down. Alex and Guillermo managed to close the hatches and secure the situation whilst inverted. Alex immediately hit the keel button, bringing the IMOCA back upright.

 

AFAIK this is the first time an IMOCA has actually been righted from a capsize (outside of the silly test) by flicking the keel, am I right? Has AT or Altadil confirmed that the boat was rolled all the way over?

you did read that they had to tip the keel to the other side, right?

 

What we read was, AT managed..."to hit the keel button".

 

The question I was most interested in getting an answer from the collective memory is the first i.e. whether anyone could recall an IMOCA (or any other canting keel boat) recovering from a full on capsize at sea under it's own power?

 

The second I asked because I tend not to trust possibly hyperbolic press releases from "sarah" who may or may not be sailor, who maybe Clean knows because he bought her a beer at a pub in Gosford when he was over there to interview AT, but who was definitely not on the #$%&ing boat. I'm trying not to call you (i.e. Mr. Clean) a piece of anatomy that rhymes with "splat" but it's getting very difficult.

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Spoke to Alex an hour ago. In good spirits with the boat alongside in Spain. He will get a few hours sleep and then we will talk, and he agreed to do it via video skype so I can record it straight to the laptop and get it up quickly.

Al, since everybody here (well most of 'em :-) have been clambering over each other to get onto their soap boxes, would be good to hear, blow by blow, what really went down from the moment they knew things were going tits up.

 

 

Prob have to go back a long way!

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new press release from AT. Nothing new I am afraid

 

http://www.alexthomsonracing.com/alex-thomson-racing-are-determined-to-succeed/

Sheesh. This time the release is by "Amanda" from Marketing and Sponsorship. I'm getting really cynical about these 'reports'--especially when the other 60s with issues seem so open.

 

The only mention of the initial problem is written off as "whilst travelling south west the yacht incurred some structural damage."

 

After the openess of Mark Turner's team management of Dongfeng in the VOR, HB's team management is really a letdown.

 

I've been interested in AT's story for a few years, but maybe pominfrance wins this one.

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new press release from AT. Nothing new I am afraid

 

http://www.alexthomsonracing.com/alex-thomson-racing-are-determined-to-succeed/

Sheesh. This time the release is by "Amanda" from Marketing and Sponsorship. I'm getting really cynical about these 'reports'--especially when the other 60s with issues seem so open.

 

The only mention of the initial problem is written off as "whilst travelling south west the yacht incurred some structural damage."

 

After the openess of Mark Turner's team management of Dongfeng in the VOR, HB's team management is really a letdown.

 

I've been interested in AT's story for a few years, but maybe pominfrance wins this one.

 

come on, they brought the boat in to the dock today. it's late evening here in our part of the world (10.15 pm at the time of writing) , do you expect them to deal with news reports before anything else? Clean already said he has an interview with Alex scheduled for tomorrow morning. And yes that would be a French morning, not your morning.

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according to AT's page

Whilst waiting for the weather to clear a rogue wave caught HUGO BOSS causing the yacht to turn upside down. Alex and Guillermo managed to close the hatches and secure the situation whilst inverted. Alex immediately hit the keel button, bringing the IMOCA back upright.

 

AFAIK this is the first time an IMOCA has actually been righted from a capsize (outside of the silly test) by flicking the keel, am I right? Has AT or Altadil confirmed that the boat was rolled all the way over?

 

you did read that they had to tip the keel to the other side, right?

What we read was, AT managed..."to hit the keel button".

The question I was most interested in getting an answer from the collective memory is the first i.e. whether anyone could recall an IMOCA (or any other canting keel boat) recovering from a full on capsize at sea under it's own power?

 

The second I asked because I tend not to trust possibly hyperbolic press releases from "sarah" who may or may not be sailor, who maybe Clean knows because he bought her a beer at a pub in Gosford when he was over there to interview AT, but who was definitely not on the #$%&ing boat. I'm trying not to call you (i.e. Mr. Clean) a piece of anatomy that rhymes with "splat" but it's getting very difficult.

I was with you right up till the second paragraph........... After that........ You lost me.

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That's what i thought:" deformation takes energy (work = force * deflection).". I can speak about sailboards, and stiffer faster, although your knees suffer more.

 

 

Stiffer isn't always faster. Stiffer board is faster, but on a board unlike a yacht the hull is not structurally coupled to the rig. See Terry's post above. On sailboards as on fast skiffs, flexibility in the rig is absolutely essential to maintaining speed and control. Maybe there are better ways to get that in a yacht than letting the hull flex, but surely you need a bit of give.

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That's what i thought:" deformation takes energy (work = force * deflection).". I can speak about sailboards, and stiffer faster, although your knees suffer more.

 

 

Stiffer isn't always faster. Stiffer board is faster, but on a board unlike a yacht the hull is not structurally coupled to the rig. See Terry's post above. On sailboards as on fast skiffs, flexibility in the rig is absolutely essential to maintaining speed and control. Maybe there are better ways to get that in a yacht than letting the hull flex, but surely you need a bit of give.

 

+1. Just seems that fast boat designers don't understand flexibility well enough to incorporate it into design. Imagine driving a 4 x 4 off road without springs.

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You experts might enjoy this description of George Pocok's racing (rowing) shell design from the days of building hulls with wood:

“There was one more thing about cedar—a sort of secret that Pocock had discovered accidentally after his first shells made of the wood had been in the water for a while. People had taken to calling them “banana boats,” because once they were exposed to water both their bows and sterns tended to curve ever so slightly upward. Pocock pondered this effect and its consequences and gradually came to a startling realization. Although cedar does not expand or swell across the grain of the wood when wet, and thus tends not to warp, it does expand slightly along the grain. This can amount to as much as an inch of swelling in the length of a sixty-foot shell. Because the cedar was dry when attached to the frame but then became wet after being used regularly, the wood wanted to expand slightly in length. However, the interior frame of the boat, being made of ash that remained perpetually dry and rigid, would not allow it to expand. The cedar skin thus became compressed, forcing the ends of the boat up slightly and lending it what boatbuilders call “camber.” The result was that the boat as a whole was under subtle but continual tension caused by the unreleased compression in the skin, something like a drawn bow waiting to be released. This gave it a kind of liveliness, a tendency to spring forward on the catch of the oars in a way that no other design or material could duplicate.

To Pocock, this unflagging resilience—this readiness to bounce back, to keep coming, to persist in the face of resistance—was the magic in cedar, the unseen force that imparted life to the shell. And as far as he was concerned, a shell that did not have life in it was a shell that was unworthy of the young men who gave their hearts to the effort of moving it through the water.”
Excerpt From: Daniel James Brown. “The Boys in the Boat.”

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That's what i thought:" deformation takes energy (work = force * deflection).". I can speak about sailboards, and stiffer faster, although your knees suffer more.

 

 

Stiffer isn't always faster. Stiffer board is faster, but on a board unlike a yacht the hull is not structurally coupled to the rig. See Terry's post above. On sailboards as on fast skiffs, flexibility in the rig is absolutely essential to maintaining speed and control. Maybe there are better ways to get that in a yacht than letting the hull flex, but surely you need a bit of give.

 

+1. Just seems that fast boat designers don't understand flexibility well enough to incorporate it into design. Imagine driving a 4 x 4 off road without springs.

 

 

Imagine a 50-131 foot trimaran design, with-out the appropriate flex designed in, I cant.

 

I would suggest that designers do design, for many aspects of their boats, flex being only one part of the many design considerations.

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new press release from AT. Nothing new I am afraid

 

http://www.alexthomsonracing.com/alex-thomson-racing-are-determined-to-succeed/

Sheesh. This time the release is by "Amanda" from Marketing and Sponsorship. I'm getting really cynical about these 'reports'--especially when the other 60s with issues seem so open.

 

The only mention of the initial problem is written off as "whilst travelling south west the yacht incurred some structural damage."

 

After the openess of Mark Turner's team management of Dongfeng in the VOR, HB's team management is really a letdown.

 

I've been interested in AT's story for a few years, but maybe pominfrance wins this one.

 

 

Now I feel bad, i'm sure they are all very nice. Just something about it all....

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Imagine a 50-131 foot trimaran design, with-out the appropriate flex designed in, I cant.

 

I would suggest that designers do design, for many aspects of their boats, flex being only one part of the many design considerations.

 

 

You would think. Do you reckon designers start with "Let's make sure we have enough flex"? Or is it "the bastard is going to flex more than we want no matter what we do, so let's eliminate as much flex as we can then work around what's left"? Which is cool right up to the point where for the first time in history what's left isn't enough.

 

Just blowing smoke here - I have no idea really, yacht designers are probably all over this.

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+1. Just seems that fast boat designers don't understand flexibility well enough to incorporate it into design. Imagine driving a 4 x 4 off road without springs.

 

4x4 is a funny one to use as an example. Older 4x4s were built on a ladder chassis. (Toyota still do put their Prado and Landcruiser based models on them). Ladder chassis flex, basically because they don't have enough torsional rigidity. On an off road vehicle you end up having to provide additional flexibility in the mounting of the cabin, and the flexing chassis will twist the entire cabin. Modern 4x4 designs have most all moved to monocoque construction. It is lighter and much more rigid. A good example is the Range Rover. On an old Range Rover you can see the bull-bar flex as you travel over rough terrain - it is mounted to the chassis and waggles about as the chassis flexes. Indeed the entire driving experience is modified by the flexing chassis. And not in a good way. The recent Range Rovers are a very rigid monocoque and the entire system is much stiffer and much lighter (especially in the most recent model.) You still have serious suspension (long travel springs, and on a Range Rover, air bag suspension). But removing the flex in the chassis allows a much better ride to be delivered, and much improved handling as as well.

Some people are not convinced that the latest model Range Rover - which has lost 400kg versus the previous model - is going to have the same long term resilience when used off road. Both are monocoque, but 400kg is a lot of mass to shed and keep the strength.

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