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2012 A-class Europeans lake Garda


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#101 k2mav

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Posted 03 July 2012 - 02:33 PM

HQ Video of the event by InGarda Trentino . Report from Landy later.


#102 SimonN

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Posted 04 July 2012 - 06:38 AM

Sorry to bring this back on subject(!) but I didn't want to reply until I had spoken to a few people who were there but who don't post.

The pictures looked like a fantastic event. In my mind, I'd love to hear about the following:

1. Who was trapezing downwind? Did it work? In the pictures that were posted, there was a good sequence of Brewin trapping downwind (but you could see Benson in the background sitting on his tramp). Did Landy and Fields sail from the string downwind?

Stevie was surprised that people do not seem to be pushing boats that hard downwind. I have heard from a number of people that Stevie was consistantly very quick off wind and did a lot of trapezing. Stevie thought Brad was very quick downwind because he was pushing hard (you see Brad trapping downhill on the video). I didn't hear comment about Landy.

2. What is the consensus on the new ARC mast? It looks like Arno had his best result ever in a major championship (10th, way to go!).

Stevie used one and didn't get a chance to sail with it until the first race. He didn't get it set up right until nearly the end. It seems they are different to what he was used to, being stiffer low down but he felt he did get it to work in the end. All told, he felt he didn't have enough time to fully evaluate the mast.

3. Any insights to what sailors are doing with their boards downwind, specifically is it fast to raise the windward board when flying a hull? Is any advantage so small that it's not worth the effort for the singlehanded sailor? I could not see anyone doing it in any of the pictures where I thought we were not looking at an offset leg.

Stevie had a few issues due to it being a new boat and not having time to sort it. He usually manages to get the boards so he can raise the windward one from the wire just before the spreader leg or on it. He couldn't do that on this boat. However, he felt that when out on teh wire, he rpefered to have both boards down, although on his Oz boat, he prefers to have the windward one up! They are 2 diiferent boards (new style at Garda, old back home) but I don't quite understand this! He is still convinced that if you are not trapezing, you need to raise the windward board. He reported that Jack's boards were also so tight that he struggled to be able to lift them and you lose too much messing about if it isn't set up right.

Hope that helps. :)

#103 k2mav

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Posted 04 July 2012 - 12:42 PM

Europeans Report by Landy here

#104 pontoon

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Posted 04 July 2012 - 01:13 PM

The report from chris field about the euro's can be found European A-cat 2012 by Chris Field

#105 k2mav

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Posted 04 July 2012 - 01:30 PM

The report from chris field about the euro's can be found European A-cat 2012 by Chris Field


Mailed Hans for his report, he sent that one seconds ago. Will post it , Arno has just posted in his site too.

#106 AClass USA 230

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Posted 05 July 2012 - 04:41 PM

Sorry to bring this back on subject(!) but I didn't want to reply until I had spoken to a few people who were there but who don't post.


The pictures looked like a fantastic event. In my mind, I'd love to hear about the following:

1. Who was trapezing downwind? Did it work? In the pictures that were posted, there was a good sequence of Brewin trapping downwind (but you could see Benson in the background sitting on his tramp). Did Landy and Fields sail from the string downwind?

Stevie was surprised that people do not seem to be pushing boats that hard downwind. I have heard from a number of people that Stevie was consistantly very quick off wind and did a lot of trapezing. Stevie thought Brad was very quick downwind because he was pushing hard (you see Brad trapping downhill on the video). I didn't hear comment about Landy.

2. What is the consensus on the new ARC mast? It looks like Arno had his best result ever in a major championship (10th, way to go!).

Stevie used one and didn't get a chance to sail with it until the first race. He didn't get it set up right until nearly the end. It seems they are different to what he was used to, being stiffer low down but he felt he did get it to work in the end. All told, he felt he didn't have enough time to fully evaluate the mast.

3. Any insights to what sailors are doing with their boards downwind, specifically is it fast to raise the windward board when flying a hull? Is any advantage so small that it's not worth the effort for the singlehanded sailor? I could not see anyone doing it in any of the pictures where I thought we were not looking at an offset leg.

Stevie had a few issues due to it being a new boat and not having time to sort it. He usually manages to get the boards so he can raise the windward one from the wire just before the spreader leg or on it. He couldn't do that on this boat. However, he felt that when out on teh wire, he rpefered to have both boards down, although on his Oz boat, he prefers to have the windward one up! They are 2 diiferent boards (new style at Garda, old back home) but I don't quite understand this! He is still convinced that if you are not trapezing, you need to raise the windward board. He reported that Jack's boards were also so tight that he struggled to be able to lift them and you lose too much messing about if it isn't set up right.

Hope that helps. :)


Thanks for the feedback. Regarding trapping downwind, after reading this, reading Landy's report on Cat Sailing, and talking to Ben Moon, it's a skill worth having in your arsenal but I think the consensus is a smart and accomplished sailor can be very close not doing it (i.e. Scott Anderson). Seems to me it is a risk/reward decision on the race course. You can make a gain provided you sail the run tactically correct but you have to be sure not to go over the bows. Some sailors obviously feel the risk is not worth the potential gain and stay on the tramp.

Regarding sails and masts, I think the Glaser Den Ben and Fiberfoam combo also seem to be working well per Ben Moon's performance and also Bruce Mahoney who finished in the top 20 in his first ever major A-Class championship. While I'd love to consider a Landy or Hammer sail, Jay Glaser is very accessible to US sailors so I expect at the WC in Florida, we could see a podium finish for a Glaser sail.

I agree 100% in marginal hull flying conditions downwind, the windward board needs to be up (if you have time). And I agree that the DNA boards are just about the tightest fitting boards I've ever seen on an A-Class (at least the new ones are). I liberally spray with McLube before a day on the water.

#107 sosoomii

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Posted 10 July 2012 - 07:07 PM

Landy in chick lit shock

Not just European champion, but a housewife's dream?

#108 AUS

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Posted 10 July 2012 - 08:41 PM



#109 pontoon

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Posted 16 July 2012 - 02:17 PM

We did put up a little report about the Vision and it's development so far.
It can be found at http://www.catamaran...nl/Reports.html

#110 MountainCat

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Posted 16 July 2012 - 04:16 PM

We did put up a little report about the Vision and it's development so far.
It can be found at http://www.catamaran...nl/Reports.html

Hans,

Congratulations on the performance of the Vision. The Vision is obviously a fast boat and the equal of the other top boat designs. I am interested in the Vision and would like more technical information about both the boat and the mast.

The Vision analysis at the link is mostly a list of unsubstantiated claims with very little technical information with the exception of the bow shape explanation. IMHO Catamaran Parts and other A-cat builders would benefit from providing a thorough and ongoing technical discussion of their boat designs similar to what the DNA people have done on their blog. Americans as well as other sailors are going to be hesitant to buy any of the new European A-cat designs without substantially more information.

In particular, I would like answers to the following questions:
  • How does the hull shape differ from other top boat designs and how do these differences benefit the Vision?
  • A claim is made that the Vision is "the stiffest we have measured by a factor of 2 or more." How was this test performed?
  • What other boat designs were tested for stiffness?
  • What accounts for this increased stiffness?
  • How does the Saarberg mast differ in flex and construction from the Fiberfoam mast?
  • Questions on the long term durability of foam have been raised in this post without satisfying answers. Can you provide relevant fatigue SN charts for both honeycomb and foam cored panels for comparison?


#111 Börni

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Posted 16 July 2012 - 05:55 PM

At around 1:52: Really interesting to see the difference of downwind trapezing. Much faster and it seems not higher compared to the rest.




#112 flojo

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Posted 17 July 2012 - 11:26 AM


We did put up a little report about the Vision and it's development so far.
It can be found at http://www.catamaran...nl/Reports.html

Hans,

Congratulations on the performance of the Vision. The Vision is obviously a fast boat and the equal of the other top boat designs. I am interested in the Vision and would like more technical information about both the boat and the mast.

The Vision analysis at the link is mostly a list of unsubstantiated claims with very little technical information with the exception of the bow shape explanation. IMHO Catamaran Parts and other A-cat builders would benefit from providing a thorough and ongoing technical discussion of their boat designs similar to what the DNA people have done on their blog. Americans as well as other sailors are going to be hesitant to buy any of the new European A-cat designs without substantially more information.

In particular, I would like answers to the following questions:
  • How does the hull shape differ from other top boat designs and how do these differences benefit the Vision?
  • A claim is made that the Vision is "the stiffest we have measured by a factor of 2 or more." How was this test performed?
  • What other boat designs were tested for stiffness?
  • What accounts for this increased stiffness?
  • How does the Saarberg mast differ in flex and construction from the Fiberfoam mast?
  • Questions on the long term durability of foam have been raised in this post without satisfying answers. Can you provide relevant fatigue SN charts for both honeycomb and foam cored panels for comparison?

I asked Hans almost the same questions way back in post 74. No answer until now. Perhaps still struggling with the term "factor of 2 or more".

#113 pontoon

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Posted 18 July 2012 - 07:46 AM

Dear all,

Sorry for the late reply but the work is asking a lot of me, please find the answers below on the questions.

Straight questions need straight answers.

1. The bow of the Vision is square to the waterline. This gives the opportunity to make the front part slab sided, which provides more volume when the bow goes down into the water. Not having a pear shape cross section does away with the negative force pushing the bow further down once it enters a wave, hence less tendency to pitch pole. This explains why the need to trapeze downwind is shifted to a later stage when wind increases. Further back the hull is not flattened under the waterline and remains curved.

2. The torsional stiffness of the platform was tested putting it on 3 solid posts at each end of the hull except one bow. Hanging a weight of 20 kg on the mast support of the front beam. Then measuring the distance to the floor on both bows. After that you do the same on leaving the other bow unsupported. Take the difference of the measurements of each bow and then take the average of the 2. This gives you an average twist of the platform.

3. The comparison was done with a DNA earlier this year, the latest new design and supposedly very stiff. Older designs like the Tool and the Flyer were no match. If you look at photos of the latest EC, they support the real measurement.

4. The stiffness of the Vision platform was derived by torsional stiff hulls, straight special carbon knitted beams and the way the beams are connected to the hulls. Curved beams are torsional weaker.

5. The Saarberg mast has a lay-up of more different layers and is stiffer in the lower part. By exploiting directional stiffness of the material and the way the mast is baked, weight is saved as well, making it lighter compared to other masts, we are pursuing an even bent under load, making life easier for the sail maker. The extra sideway stiffness was first exploited on the Saarberg mast.

6. The long term durability of a platform is hard to test as nobody has the ability to test like they do i.e. in the car industry. The universal way of building with foam was a long time the industry standard, with only a few boats being built with honeycomb. Those old foam boats are still around everywhere. Honeycomb is very good material when used correctly. There is absolutely an advantage in panel stiffness. Torsional stiffness is another thing. We believe it is different here. No laboratory test have been done, but the design of the hull, the choice of the properties of the foam itself and the way the laminate was produced gave a very stiff Vision hull. The sensitivity to sudden impact and high load hits in foam are superior to honeycomb, which helps longevity. The lay-up of the hull’s skin is not much different from honeycomb hulls, so no weight is saved there. To bond honeycomb often an extra layer of bonding film is used and at the edges filler is used to get a more even cross over. This is where there is extra weight making the advantage of the honeycomb weight lower. The only way to get a real technical answer here is to test under laboratory control on the different aspects. So we hope somebody can invest in testing panel stiffness, torsional stiffness, and impact absorbing ability, which would give more satisfying answers.


Best regards,

Hans

#114 flojo

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Posted 18 July 2012 - 10:34 AM

Dear all,

Sorry for the late reply but the work is asking a lot of me, please find the answers below on the questions.

Straight questions need straight answers.

1. The bow of the Vision is square to the waterline. This gives the opportunity to make the front part slab sided, which provides more volume when the bow goes down into the water. Not having a pear shape cross section does away with the negative force pushing the bow further down once it enters a wave, hence less tendency to pitch pole. This explains why the need to trapeze downwind is shifted to a later stage when wind increases. Further back the hull is not flattened under the waterline and remains curved.

2. The torsional stiffness of the platform was tested putting it on 3 solid posts at each end of the hull except one bow. Hanging a weight of 20 kg on the mast support of the front beam. Then measuring the distance to the floor on both bows. After that you do the same on leaving the other bow unsupported. Take the difference of the measurements of each bow and then take the average of the 2. This gives you an average twist of the platform.

3. The comparison was done with a DNA earlier this year, the latest new design and supposedly very stiff. Older designs like the Tool and the Flyer were no match. If you look at photos of the latest EC, they support the real measurement.

4. The stiffness of the Vision platform was derived by torsional stiff hulls, straight special carbon knitted beams and the way the beams are connected to the hulls. Curved beams are torsional weaker.

5. The Saarberg mast has a lay-up of more different layers and is stiffer in the lower part. By exploiting directional stiffness of the material and the way the mast is baked, weight is saved as well, making it lighter compared to other masts, we are pursuing an even bent under load, making life easier for the sail maker. The extra sideway stiffness was first exploited on the Saarberg mast.

6. The long term durability of a platform is hard to test as nobody has the ability to test like they do i.e. in the car industry. The universal way of building with foam was a long time the industry standard, with only a few boats being built with honeycomb. Those old foam boats are still around everywhere. Honeycomb is very good material when used correctly. There is absolutely an advantage in panel stiffness. Torsional stiffness is another thing. We believe it is different here. No laboratory test have been done, but the design of the hull, the choice of the properties of the foam itself and the way the laminate was produced gave a very stiff Vision hull. The sensitivity to sudden impact and high load hits in foam are superior to honeycomb, which helps longevity. The lay-up of the hull’s skin is not much different from honeycomb hulls, so no weight is saved there. To bond honeycomb often an extra layer of bonding film is used and at the edges filler is used to get a more even cross over. This is where there is extra weight making the advantage of the honeycomb weight lower. The only way to get a real technical answer here is to test under laboratory control on the different aspects. So we hope somebody can invest in testing panel stiffness, torsional stiffness, and impact absorbing ability, which would give more satisfying answers.


Best regards,

Hans

Thanks for your explanations, Hans.
And now for the numbers: What's the average "bow drop measurement" of the Vision according to your procedure?
Do you use three identical posts or are you aligning the waterline with the floor?
flojo

#115 SimonN

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Posted 18 July 2012 - 03:21 PM

Hans

First off, congrats. it is clear that the Vision is a very competitive platform and anything i say below isn't meant to contradict that. However, some of your comments aren't, IMO, quite right.

1. The bow of the Vision is square to the waterline. This gives the opportunity to make the front part slab sided, which provides more volume when the bow goes down into the water. Not having a pear shape cross section does away with the negative force pushing the bow further down once it enters a wave, hence less tendency to pitch pole. Sorry, but this is a commonly held view that I believe is incorrect. If you are saying that the Vision doesn't pitchpole as easily as some other designs, the reason has to be elsewhere. If the only difference was the bows, your shape would pitchpole more. The reason for this that the bow goes down, the extra volume and wider waterline increases drag, slowing the boat, which in turn increases the pitchpole action. The other misconception about the "wave piercing" bow driving the boat under is thinking that the water flow along the hull remains horizontal. If it did, the bow would be driven down but the water flow goes with the direction of travel. Imagine you tip a hull 90 degrees to the water and drop it. The water will still flow along the hull as the boat goes down into the water. The reason for the "wave piercing" bow is that as it is driven down, it minimises the changes in displacement and therefore minimises drag, making it easier to recover. You won't see any AC72's with your style of bow for exactly this reason

This explains why the need to trapeze downwind is shifted to a later stage when wind increases. Further back the hull is not flattened under the waterline and remains curved.Now you hit the real reason why your boat doesn't pitchpole as easily. It will be because of a combination of the rocker profile and the bouyancy distribution. Now, I am not saying that the Vision would be faster with a wave piercing bow, because there are a whole load of things that combine to make a hullshape behave the way it does. All I am saying is that I question your particular explanation

2. The torsional stiffness of the platform was tested putting it on 3 solid posts at each end of the hull except one bow. Hanging a weight of 20 kg on the mast support of the front beam. Then measuring the distance to the floor on both bows. After that you do the same on leaving the other bow unsupported. Take the difference of the measurements of each bow and then take the average of the 2. This gives you an average twist of the platform. I am not sure why you put the weight where you do. Whenever I have tested platform stufness on a cat, I simply hang the weight on the untied down bow. I also repeat the tests on the back of the boat as well.

3. The comparison was done with a DNA earlier this year, the latest new design and supposedly very stiff. Older designs like the Tool and the Flyer were no match. If you look at photos of the latest EC, they support the real measurement.FWIW, I would have expected this based on a number of factors. The DNA is far more torsionally stiff than older platforms, but is nowhere near as stif as can be built

4. The stiffness of the Vision platform was derived by torsional stiff hulls, straight special carbon knitted beams and the way the beams are connected to the hulls. Curved beams are torsional weaker.While all of this is correct, be careful not to get too obsessed with torsional stiffness. There are other loads on the platform as well. You really do need to consider torsional stiffness with the mast up, and even then, the amount of rig tension being used makes a huge difference. for instance, C Class cats don't have a lot of torsional stiffness until the mast goes in and they achieve it through the mast, shrouds and forestay. Curved beams are far better at handling the compressive loads of rig than straight beams. In theory, D shaped beams (or even box section as we see on the rear beam of the ETNZ AC72) are also a better compromise that round ones.

5. The Saarberg mast has a lay-up of more different layers and is stiffer in the lower part. By exploiting directional stiffness of the material and the way the mast is baked, weight is saved as well, making it lighter compared to other masts, we are pursuing an even bent under load, making life easier for the sail maker. The extra sideway stiffness was first exploited on the Saarberg mast.You will be pleased to hear I won't argue with you over masts. I use one and won't change :)

6. The long term durability of a platform is hard to test as nobody has the ability to test like they do i.e. in the car industry. The universal way of building with foam was a long time the industry standard, with only a few boats being built with honeycomb. Those old foam boats are still around everywhere. Honeycomb is very good material when used correctly. There is absolutely an advantage in panel stiffness. Torsional stiffness is another thing. We believe it is different here. No laboratory test have been done, but the design of the hull, the choice of the properties of the foam itself and the way the laminate was produced gave a very stiff Vision hull. The sensitivity to sudden impact and high load hits in foam are superior to honeycomb, which helps longevity. The lay-up of the hull’s skin is not much different from honeycomb hulls, so no weight is saved there. To bond honeycomb often an extra layer of bonding film is used and at the edges filler is used to get a more even cross over. This is where there is extra weight making the advantage of the honeycomb weight lower. The only way to get a real technical answer here is to test under laboratory control on the different aspects. So we hope somebody can invest in testing panel stiffness, torsional stiffness, and impact absorbing ability, which would give more satisfying answers.There is lots of data on this and the benefits of honeycomb are well documented. If a builder cannot gain significant weight savings from honeycomb, they shouldn't be using it, but constructed correctly, those weight savings are there. As for longevity, again there is significant data. I do agree that foam can be more forgiving than honeycomb with high impacts, but as Ben has reported, built correctly, a honeycomb A Class can be very impressive. It is also very hard to use real life examples to show how long boats last becasue of vastly differing construction techniques. I cannot think of any examples where boats have been built to the same spec except for foam or honeycomb cores. But there are well known examples of honeycomb boats having vastly longer competitive lifespans than foam boats. How much of that is down to other factors is hard to say.


Best regards,

Hans

Finally, please don't misunderstand me. I am in no way saying that the Vision is bad, has faults or even could be better. This is meant purely as comment on your techical analysis and not on the design and construction of the particular boat.

#116 Dyneema_forever

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Posted 18 July 2012 - 03:54 PM

Hans

First off, congrats. it is clear that the Vision is a very competitive platform and anything i say below isn't meant to contradict that. However, some of your comments aren't, IMO, quite right.


1. The bow of the Vision is square to the waterline. This gives the opportunity to make the front part slab sided, which provides more volume when the bow goes down into the water. Not having a pear shape cross section does away with the negative force pushing the bow further down once it enters a wave, hence less tendency to pitch pole. Sorry, but this is a commonly held view that I believe is incorrect. If you are saying that the Vision doesn't pitchpole as easily as some other designs, the reason has to be elsewhere. If the only difference was the bows, your shape would pitchpole more. The reason for this that the bow goes down, the extra volume and wider waterline increases drag, slowing the boat, which in turn increases the pitchpole action. The other misconception about the "wave piercing" bow driving the boat under is thinking that the water flow along the hull remains horizontal. If it did, the bow would be driven down but the water flow goes with the direction of travel. Imagine you tip a hull 90 degrees to the water and drop it. The water will still flow along the hull as the boat goes down into the water. The reason for the "wave piercing" bow is that as it is driven down, it minimises the changes in displacement and therefore minimises drag, making it easier to recover. You won't see any AC72's with your style of bow for exactly this reason

This explains why the need to trapeze downwind is shifted to a later stage when wind increases. Further back the hull is not flattened under the waterline and remains curved.Now you hit the real reason why your boat doesn't pitchpole as easily. It will be because of a combination of the rocker profile and the bouyancy distribution. Now, I am not saying that the Vision would be faster with a wave piercing bow, because there are a whole load of things that combine to make a hullshape behave the way it does. All I am saying is that I question your particular explanation

2. The torsional stiffness of the platform was tested putting it on 3 solid posts at each end of the hull except one bow. Hanging a weight of 20 kg on the mast support of the front beam. Then measuring the distance to the floor on both bows. After that you do the same on leaving the other bow unsupported. Take the difference of the measurements of each bow and then take the average of the 2. This gives you an average twist of the platform. I am not sure why you put the weight where you do. Whenever I have tested platform stufness on a cat, I simply hang the weight on the untied down bow. I also repeat the tests on the back of the boat as well.

3. The comparison was done with a DNA earlier this year, the latest new design and supposedly very stiff. Older designs like the Tool and the Flyer were no match. If you look at photos of the latest EC, they support the real measurement.FWIW, I would have expected this based on a number of factors. The DNA is far more torsionally stiff than older platforms, but is nowhere near as stif as can be built

4. The stiffness of the Vision platform was derived by torsional stiff hulls, straight special carbon knitted beams and the way the beams are connected to the hulls. Curved beams are torsional weaker.While all of this is correct, be careful not to get too obsessed with torsional stiffness. There are other loads on the platform as well. You really do need to consider torsional stiffness with the mast up, and even then, the amount of rig tension being used makes a huge difference. for instance, C Class cats don't have a lot of torsional stiffness until the mast goes in and they achieve it through the mast, shrouds and forestay. Curved beams are far better at handling the compressive loads of rig than straight beams. In theory, D shaped beams (or even box section as we see on the rear beam of the ETNZ AC72) are also a better compromise that round ones.

5. The Saarberg mast has a lay-up of more different layers and is stiffer in the lower part. By exploiting directional stiffness of the material and the way the mast is baked, weight is saved as well, making it lighter compared to other masts, we are pursuing an even bent under load, making life easier for the sail maker. The extra sideway stiffness was first exploited on the Saarberg mast.You will be pleased to hear I won't argue with you over masts. I use one and won't change :)

6. The long term durability of a platform is hard to test as nobody has the ability to test like they do i.e. in the car industry. The universal way of building with foam was a long time the industry standard, with only a few boats being built with honeycomb. Those old foam boats are still around everywhere. Honeycomb is very good material when used correctly. There is absolutely an advantage in panel stiffness. Torsional stiffness is another thing. We believe it is different here. No laboratory test have been done, but the design of the hull, the choice of the properties of the foam itself and the way the laminate was produced gave a very stiff Vision hull. The sensitivity to sudden impact and high load hits in foam are superior to honeycomb, which helps longevity. The lay-up of the hull's skin is not much different from honeycomb hulls, so no weight is saved there. To bond honeycomb often an extra layer of bonding film is used and at the edges filler is used to get a more even cross over. This is where there is extra weight making the advantage of the honeycomb weight lower. The only way to get a real technical answer here is to test under laboratory control on the different aspects. So we hope somebody can invest in testing panel stiffness, torsional stiffness, and impact absorbing ability, which would give more satisfying answers.There is lots of data on this and the benefits of honeycomb are well documented. If a builder cannot gain significant weight savings from honeycomb, they shouldn't be using it, but constructed correctly, those weight savings are there. As for longevity, again there is significant data. I do agree that foam can be more forgiving than honeycomb with high impacts, but as Ben has reported, built correctly, a honeycomb A Class can be very impressive. It is also very hard to use real life examples to show how long boats last becasue of vastly differing construction techniques. I cannot think of any examples where boats have been built to the same spec except for foam or honeycomb cores. But there are well known examples of honeycomb boats having vastly longer competitive lifespans than foam boats. How much of that is down to other factors is hard to say.


Best regards,

Hans

Finally, please don't misunderstand me. I am in no way saying that the Vision is bad, has faults or even could be better. This is meant purely as comment on your techical analysis and not on the design and construction of the particular boat.


Cant wait for the 'perfect' SimonN-A-Cat ;)

#117 AClass USA 230

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Posted 18 July 2012 - 05:06 PM

US A-Class sailor, designer and builder, and mast/boat repair guru OH Rodgers made an interesting comment to me this spring regarding A-Class design and how to design a boat that minimizes the pitch poling tendency in big breeze and chop/waves. The conversation above regarding the Vision design basis versus the other current A-Class designs questions the logic of the wave piercer concept. SimonN makes a valid point that if the wave piercer concept was flawed, then the AC guys are spending a lot of money going in the wrong direction! But getting back to OH, he commented to me that the volume distribution of the boat around the front beam area is really critical to whether the boat will sail bow up downwind in breeze and waves. That seems to make some sense to me as the CG of the boat is behind the front beam. I'm not a designer, just a listener and I found his comment interesting in light of the conversation above.

But it's great that so many designs seem to be so similar that even though the class is development by definition, the racing seems very one design for sure if you have a current kit and have put the time in on it.

#118 SimonN

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Posted 18 July 2012 - 09:17 PM

Cant wait for the 'perfect' SimonN-A-Cat ;)

I wish! The easy bit is sorted. I do have the person I believe to be one of the best composites boat builder lined up and ready to go, with all the engineering done etc. But there are 3 problems.

1. Money. To do this properly needs a fairly big investment to get the tooling, money I don't have. Every time I think I have a chance of getting a group together so as to spread the cost, somebody goes and buys an existing boat.

2. Demand. With the strength of the Aussie dollar, building boats here and sending them overseas would, I believe, price us out of the market. And the demand in Oz won't be that high because a lot of people have replaced their boats in the last couple of years - I think there have been something like 30 boats brought in from Europe.

3. Deciding on a design. If I was totally convinced that there is a design breakthrough to build, it might change things but at the moment, the class is well served by a range of designs which are available in good enough quantity and quality. Building a small variant of an existiung boat to the highest possible standard isn't going to make enough difference for everybody to change their boat.

There are a couple of projects underway down here in Oz and I wish them the best of luck but at the moment, I cannot even afford a new boat never mind funding new moulds etc. :(

#119 flojo

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Posted 19 July 2012 - 07:26 AM


Cant wait for the 'perfect' SimonN-A-Cat ;)

I wish! The easy bit is sorted. I do have the person I believe to be one of the best composites boat builder lined up and ready to go, with all the engineering done etc. But there are 3 problems.

1. Money. To do this properly needs a fairly big investment to get the tooling, money I don't have. Every time I think I have a chance of getting a group together so as to spread the cost, somebody goes and buys an existing boat.

2. Demand. With the strength of the Aussie dollar, building boats here and sending them overseas would, I believe, price us out of the market. And the demand in Oz won't be that high because a lot of people have replaced their boats in the last couple of years - I think there have been something like 30 boats brought in from Europe.

3. Deciding on a design. If I was totally convinced that there is a design breakthrough to build, it might change things but at the moment, the class is well served by a range of designs which are available in good enough quantity and quality. Building a small variant of an existiung boat to the highest possible standard isn't going to make enough difference for everybody to change their boat.

There are a couple of projects underway down here in Oz and I wish them the best of luck but at the moment, I cannot even afford a new boat never mind funding new moulds etc. :(

Crowdfunding? In AUS ie Pozible.

#120 MountainCat

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Posted 19 July 2012 - 04:40 PM

Dear all,

Sorry for the late reply but the work is asking a lot of me, please find the answers below on the questions.

Straight questions need straight answers.

1. The bow of the Vision is square to the waterline. This gives the opportunity to make the front part slab sided, which provides more volume when the bow goes down into the water. Not having a pear shape cross section does away with the negative force pushing the bow further down once it enters a wave, hence less tendency to pitch pole. This explains why the need to trapeze downwind is shifted to a later stage when wind increases. Further back the hull is not flattened under the waterline and remains curved.

2. The torsional stiffness of the platform was tested putting it on 3 solid posts at each end of the hull except one bow. Hanging a weight of 20 kg on the mast support of the front beam. Then measuring the distance to the floor on both bows. After that you do the same on leaving the other bow unsupported. Take the difference of the measurements of each bow and then take the average of the 2. This gives you an average twist of the platform.

3. The comparison was done with a DNA earlier this year, the latest new design and supposedly very stiff. Older designs like the Tool and the Flyer were no match. If you look at photos of the latest EC, they support the real measurement.

4. The stiffness of the Vision platform was derived by torsional stiff hulls, straight special carbon knitted beams and the way the beams are connected to the hulls. Curved beams are torsional weaker.

5. The Saarberg mast has a lay-up of more different layers and is stiffer in the lower part. By exploiting directional stiffness of the material and the way the mast is baked, weight is saved as well, making it lighter compared to other masts, we are pursuing an even bent under load, making life easier for the sail maker. The extra sideway stiffness was first exploited on the Saarberg mast.

6. The long term durability of a platform is hard to test as nobody has the ability to test like they do i.e. in the car industry. The universal way of building with foam was a long time the industry standard, with only a few boats being built with honeycomb. Those old foam boats are still around everywhere. Honeycomb is very good material when used correctly. There is absolutely an advantage in panel stiffness. Torsional stiffness is another thing. We believe it is different here. No laboratory test have been done, but the design of the hull, the choice of the properties of the foam itself and the way the laminate was produced gave a very stiff Vision hull. The sensitivity to sudden impact and high load hits in foam are superior to honeycomb, which helps longevity. The lay-up of the hull's skin is not much different from honeycomb hulls, so no weight is saved there. To bond honeycomb often an extra layer of bonding film is used and at the edges filler is used to get a more even cross over. This is where there is extra weight making the advantage of the honeycomb weight lower. The only way to get a real technical answer here is to test under laboratory control on the different aspects. So we hope somebody can invest in testing panel stiffness, torsional stiffness, and impact absorbing ability, which would give more satisfying answers.


Best regards,

Hans

Hans, Thank you for your answers. They are not quite as complete as I would have liked, but I can understand the need to keep some information proprietary.

On Foam versus Honeycomb:

It seems that foam Corecell has advantages over honeycomb when used in the slamming areas of Volvo 60's and 70's. See Merf Owens post in this link: http://forums.sailin...ic=133213&st=50

Whether this experience would extend to A-cat racing longevity with its lower core densities and probably higher number of cycles is unknown. The fatigue life of panel cores is tested by stress cycling panels to failure and is recorded on fatigue SN curves. See: http://www.fkm.utm.m...2%20Fatigue.pdf

Some SN curves are available for PVC (Divinycell). I have not been able to find SN curves for either SAN (Corecell) or honeycomb (Nomex). Can anyone provide these fatigue SN charts?

If the maximum stresses a panel experiences can be reduced below the Endurance Limit by good design, then the panel can theoretically have an infinite fatigue life. Maximum panel stresses can be reduced by increasing panel thickness or by using properly designed stringers. The higher density of foam versus honeycomb at equal strength makes foam panels greater than 3/8 inch or 10 mm in thickness too heavy to reach the total minimum A-cat weight.

Based on the higher material properties of honeycomb versus foam on a density basis, the honeycomb core is likely to have a higher Endurance Limit. This means that for two identical A-cats, one foam, one honeycomb, with equal panel core thickness, say 10 mm, the honeycomb boat will have a longer life before failure (going soft).

My current opinion is that foam A-cats may be able to be weight competitive and have the same racing life (near infinite) as honeycomb if properly designed stringers are used to reduce maximum stresses in the panel cores.

#121 ita 16

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Posted 19 July 2012 - 07:49 PM

This topic is very interesting , but I do not understand why speak of longevity into a category Class A boats are obsolete in 8 months.

#122 k2mav

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Posted 19 July 2012 - 09:12 PM

This topic is very interesting , but I do not understand why speak of longevity into a category Class A boats are obsolete in 8 months.


Tell that to Nils Bunkenburg Nikitas...

#123 ita 16

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Posted 19 July 2012 - 09:56 PM

The nikita is the only exception in 40 years of history, Nils is a friend and his boat is the best, this is what I think. I insist with saying that the problem is exaggerated gold rush that the class allows.

#124 k2mav

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Posted 19 July 2012 - 11:17 PM

I've seen the same complain in the F18, what do you want? stop development?
You need OD. Wrong class to be. In my view and objective numbers in sales and events (Latest Europeans) , the A-Class is booming. So I don´t see nothing wrong.

By definition the class is expensive, but more new boats means more alternatives in the used market, so I don´t get your complain reviewing current class status quo.



#125 SimonN

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Posted 19 July 2012 - 11:28 PM

The nikita is the only exception in 40 years of history, Nils is a friend and his boat is the best, this is what I think. I insist with saying that the problem is exaggerated gold rush that the class allows.

Sorry, but if you don't like it, don't sail a development class. And there really is no exaggerated gold rush as you like to claim. You had just as much development going on in the first decade of this century without curved boards as you do today. And if you think that the class would have stopped developing if curved boards had not come along, again you are mistaken. In fact, i know of new designs which were put on hold when the DNA came out and I believe we would have seen as much, if not more development anyway.

As for boats being obselete in 8 months, again that is total bullshit! Start with the DNA. It is not outclassed, as we saw from Stevie Brewin's results once he got hgis rig sorted at the Europeans and that is now 30 months old. Even the Vision is now well over a year old and that isn't obsolete. Yes, Scheurer has updated it's design but if you are trying to say it will be outdated in 8 months, you really don't have much grasp on reality. I have gone back over the results from worlds past and can find no evidence when looking at designs that suggests that development is going any faster now than it has been in the past. The difference is that now it is more obvious, because of the curved boards. Major changes, such as moving the front beam back as many designs did, weren't so obvious as to make people believe they needed to change, even though it does make a significant difference.

The argument about how long a boat lasts has nothing to do with it how quickly it becomes obsolete. To start with, you don't know how long a design will remain competitive. Then there is the issue of the second hand market. You seem to have forgotten that many accept they cannot sail the latest, fastest design but still want to sail in the class. It is far better for the class to have a supply of strong, long lasting boats. You also have no idea whether it might be possible to modify a design in the future. For instance, I wish I could find a strong, honeycomb/carbon/epoxy Flyer 1 at the momnent. I would be prepared to pay a premium over a standard Flyer 1 for it because I know that with a bit of work, I could turn it into a boat that would be competitive at any level.

But instead of focusing in on the platforms, the other big area of change has come in the rig and this has made the gains of the new designs seem even bigger, because instead of upgrading the rigs on older boats, people have bought new boats with new rigs. So what we end up comparing is old platforms with old style rigs with new platforms with new style rigs. The difference wouldn't be anywhere near as marked if the rigs hadn't progressed in the way they have. Stick and old style rig on a new platform and you won't be doing very well. And this is something we cannot control. The moulds for the masts haven't changed. All that has changed is the lay up of the material. In the same way, the sails have progressed not because of new materials but because of new designs. The only way to chang ethat is to make the rig one design.

I can understand the frustration of some when they see their fleets shrinking. They look for something to blame and that becomes the speed of development. Yet in some countries, we see the class growing despite that. What I believe is going on is that the biggest problem is that of ecomomic crisis. In a strong ecomony like here in Australia, the class is booming. In economies in crisis, the class is struggling. I really do believe it is that simple.

#126 ita 16

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Posted 20 July 2012 - 06:59 AM

Unfortunately I have not much time to write here, or read poems idyllic,the brands you use as an example have made many changes to the boats in the last year: materials,structures,center boards,new rudders,masts and sails well in the last months, Everybody does this. I want to repeat what I said before: I believe in this class,I learn from the past,development is just but not with this exaggerated frequency.

#127 Waynemarlow

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Posted 20 July 2012 - 09:07 AM

2. Demand. With the strength of the Aussie dollar, building boats here and sending them overseas would, I believe, price us out of the market. And the demand in Oz won't be that high because a lot of people have replaced their boats in the last couple of years - I think there have been something like 30 boats brought in from Europe.


The DNA's were bought into Aus at a time when the the Aussie dollar was very much weaker than todays level, the Aussies still bought them as they were considered the latest toy and could afford them in a booming economy. No excuses on the dollar rate as the home built boats would be devoid of import duties making any Aussie built boat a bargain in comparison to the Euro boats.

Any good designer could use NZ to have boats built as there the dollar is quite weak against the Euro and they probably have a more experianced work force in making high quality composites.

#128 SimonN

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Posted 20 July 2012 - 03:20 PM


2. Demand. With the strength of the Aussie dollar, building boats here and sending them overseas would, I believe, price us out of the market. And the demand in Oz won't be that high because a lot of people have replaced their boats in the last couple of years - I think there have been something like 30 boats brought in from Europe.


The DNA's were bought into Aus at a time when the the Aussie dollar was very much weaker than todays level, the Aussies still bought them as they were considered the latest toy and could afford them in a booming economy. No excuses on the dollar rate as the home built boats would be devoid of import duties making any Aussie built boat a bargain in comparison to the Euro boats.


Wayne

This isn't actually correct. To start with, when the first batch of DNA's came over, they cost about the same price as a new Tool (built here) would have cost. This was one of the reasons why the Tool Mk2 was put on hold. And with the strengthening dollar having done better than the price rise of, say, the DNA, it is still cheaper to buy a DNA, ship it here and pay duty than it is to build one here. Before tax, a complete DNA platform is euro 15,050 which is, lets say, $18000 dollars. That's about what we would need to charge for a bare platform. The cheapest I could see us building a complete platform here of the right standard is about $24,000 ( say euro 20,000) and then you need to ship.

Add to that the fact that with all the DNA's that have been bought, there really aren't very many people looking to replace boats at the moment. When the DNA first came out, people were looking to upgrade as many were sailing boats that were 3 or 4 years old.

Any good designer could use NZ to have boats built as there the dollar is quite weak against the Euro and they probably have a more experianced work force in making high quality composites.

I have tried to play this sort of game before and have seen others do it as well. I will give anybody who is interested a tip here. If you want to build in another country, be prepared to spend a lot of time in that country and be prepared to make numerous trips. By the time you have done all that and then shipped boats over to Aus for testing etc, you really won't see any savings unless you achieve high production numbers and i really don't think the A's are ready or have the demand to see the numbers we have seen with the DNA happen in the current economic climate.

Boatbuilding is a tough way of earning a living to start with. Needing an international market to gain success adds an even greater challenge and when your key larkets are in a different hemisphere, it's even more tough.

I am far more likely to try to find a way to be able to produce a one off/limited run with no profit in mind than try to be commercial. If only there was away of building tools that could be used for prepreg cheaply........

#129 SimonN

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Posted 22 July 2012 - 12:15 AM

To take this one stage further, if anybody knows of a single Flyer 1 hull lying around, I would love to get hold of one as the basis of a plug. I have considered taking a rough mould off my boat, building a rough plug out of that, shaping, fairing it and then making a good mould, but an existing hull would save a lot of time, money and effort.

#130 NZL255

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Posted 22 July 2012 - 08:35 AM

You are right Wayne. With New Zealand being so isolated and our dollar not being as strong as others, it is very expensive to buy and import A-Cats / parts / sails down here. Most of the NZ A-Class fleet boats are designed and built by their owners. Even Mike Drummond has gone down that road.

But don't worry we're up with the rest of the world with the 2014 Worlds being held here in NZ! :)




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