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Old 21-05-2015, 09:28   #361
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Re: Is there a catamaran of cruising size that can self right unaided?

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Originally Posted by Juho View Post
No. All use cases are valid use cases. One approach would be to study all available accident reports. That should give us a reasonably balanced and wide basis for research.



No changes intended. All use cases that are relevant to the original question are valid.
Please to go forth and study! But work with real data, written by engineers, and from first hand accounts of what happened. Nothing derived from imaginations or extrapolated from risk assessments of one insurance underwriter.

Please report back with your findings so we can balance the discussion!
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Old 21-05-2015, 09:48   #362
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Re: Is there a catamaran of cruising size that can self right unaided?

Beyond 90 degree aversion. See diagram.

The diagram was a tested technology on small craft that required manual deployment, however because the craft was small it could rely on a mast float to maintain the 90 degree stability that was needed whilst an articulating bowsprit ( that was able to swing back on a hinge like a gate because of the 90 degrees capsize ) be attached to a water bag and allowed to become effectively a crane lift arm.

This arm when attached to submerged bag was able to use the load of that bag as leverage to right the boat.

It did not translate to larger craft back then because.

A: There is no mast float to stop the boat going to 90.

B: Relates to (a) yeyond 90 the tech can not work(too late)

C: The bowsprit could not be engineered to double up as a crane as it could not be made strong enough and light lift to lift the bigger loads.

However 30 years later we have advanced censors and electronics which overcomes problem of (A) above because sensors can anticipate the boat going turtle before it does happen.

Secondly we have advance materials (carbon) that allow the use of a hinged crane under the bowsprit line instead of the bowsprit itself that can be fired back very fast on a trigger due to the mass of carbon is low.

Thirdly the carbon arm engineered as a back to back arch is able to provide the load capacity to lever upright a larger boat whilst being extremely light weight itself.

Put that all together and then you are possibly able to effectively deploy a large drag anchor automatically when you need it to keep the boat at 90 degrees.

I do not know the righting forces needed but one chap the other day said that to right a hobbie when totally inverted requires a 3rd of top side weight. So lets assume the boat is 10 ton then like for like you would need a 3 ton bag but at 90 and just beyond the balance point it would be far less and in fact a relatively minimal load is needed compared to the total boat weight to maintain near equilibrium balance point. Newton's first law of uniform of motion. The mass is trying to go down and not sidways.

There is not relatively a great deal of sideways pivot force at a static 90 degress. The forces come from the acceleration on the way over.

A ballast bag on the bow end of a rearward hinged arm when dropped would be in the water very fast as the boat would be moving over it from the hinge resulting in the bag being pushed down deep. The challenge faced though is about overcoming the forces acting on the brake(lever bag) when that deployment happens from a 10 ton boat scooting along at 10 knots. The other challenge is deployment when the craft is static as this would require the punching of that that arm into deep water to get the bag operational as quickly as possible.

It was a similar problem they had to overcome when emergency chutes were deployed from aircraft. Kept failing but they solved it.

Holding a boat at 90 does not require a lot of force. The forces that are being fought and controlled is inertia, wind and wave and sail.

The set up as a standard would seem capable of lending itself to most cat designs as the hinged arm simply needs to hinge just aft of the CG with the arm itself being no more than a double sided crane boom that terminates at the bow under the deck.

If you look at some of the carbon support arches now they support tons and weigh very little and the leverage force to hold a boat at 90 and drop a boat from 90 is very little.

The problem is not destroying the brake when it is deployed and trawled at a multitude of knots.

With today’s tech I do not think it is an overly complex nut buster to get this working. I hope there is success. The problem will be to make it cheap but I don’t think it presents such high cost either and we will probably start to see these first in flying hulls as any boat even those that fly are not good for business if they go turtle a lot and it also loses its fun factor after a while..

Works for pitch pole also.

I am quite sure we will start to see this tech coming through.

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Old 21-05-2015, 10:06   #363
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Re: Is there a catamaran of cruising size that can self right unaided?

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Originally Posted by paulanthony View Post
So... let me get this straight then. Car manufacturers, designed and bought another kind of cat to the market because they thought it was a great idea?
We were not talking about another kind of car but about safety features.

Yes, Manufacturers added safety features because they thought it was a great idea. Because it was a unique selling point.

See the history of seat belts, ABS or ESC. Invented a long time ago, made available as options in some cars, then became standard for some cars. And only years or decades later they became a legal requirement for new cars.
But there was a real world problem to solve. How often have you been glad that you had ABS or ESC? Many folks don't notice these systems anymore but they are there and working in the background to save your a**. More often than most think.
on the contrary I never ever felt the need for a righting device.


If there was a perceived need for a righting device, the manufacturers would spend money on research. If they had any solution they would make it available as an option, because its a unique selling point.
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Old 21-05-2015, 10:13   #364
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Re: Is there a catamaran of cruising size that can self right unaided?

Quote:
Originally Posted by Juho View Post
No. All use cases are valid use cases. One approach would be to study all available accident reports. That should give us a reasonably balanced and wide basis for research.



No changes intended. All use cases that are relevant to the original question are valid.
Go read this story, citing first hand account of what happened.

Renegade Cruisers • View topic - Lagoon 38 capsize,

Is this use case supported in this conversation?
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Old 21-05-2015, 10:13   #365
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Re: Is there a catamaran of cruising size that can self right unaided?

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Originally Posted by paulanthony View Post
With today’s tech I do not think it is an overly complex nut buster to get this working. I hope there is success. The problem will be to make it cheap but I don’t think it presents such high cost either and we will probably start to see these first in flying hulls as any boat even those that fly are not good for business if they go turtle a lot and it also loses its fun factor after a while..

Works for pitch pole also.

I am quite sure we will start to see this tech coming through.
Seriously, when you brought this system up in your previous post I thought you were making a joke.
Now i see you take this seriously....
This IS a joke. It works on tiny toy cats in sheltered controlled environments. It won't scale and it won't work in shitty weather.

Buy a cat and go sailing. Cross an ocean. Then Re-read the thread and come back To report your progress on this idea.
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Old 21-05-2015, 10:36   #366
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Re: Is there a catamaran of cruising size that can self right unaided?

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Seriously, when you brought this system up in your previous post I thought you were making a joke.
Now i see you take this seriously....
This IS a joke. It works on tiny toy cats in sheltered controlled environments. It won't scale and it won't work in shitty weather.

Buy a cat and go sailing. Cross an ocean. Then Re-read the thread and come back To report your progress on this idea.
Physics is physics. Toy boats are subjected to the same laws as big boats and big planes.

As things get bigger we see acting forces multiplied, square and cubed. The designers and engineers then match the resisting forces where possible with suitable materials. When we can't achieve spec we tend to wait for science to provide something new so we can continue the matching process and achieve scale later.

The laws of big physics are the same for small things as they are big things and humanity has never been put off by the challenge of big numbers and scale. What works for small things generally works for big things also and often big scale provides own its own advantage in overcoming problems.

This is why we have very tall buildings, planes bigger than football pitches and ships so big we need to build special ports to accommodate them.

With all that we have achieved if you really think that a solution can not be found for capsize aversion on a large scale then you are grossly mistaken. It requires one thing only. Will!

Shitty weather is a definable mathematical problem.
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Old 21-05-2015, 11:29   #367
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Re: Is there a catamaran of cruising size that can self right unaided?

I think we may have done this topic to death. How about we change to another perennial topic that sounds good at first but has turned out not to be practical in cruising designs: main sheet fuses to prevent capsize. Here are a couple of websites to get people going:

Ganovelli Concept - Presentation ACS cruising

Syst?me anti chavirage UpSideUp

Mark.
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Old 21-05-2015, 11:42   #368
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Re: Is there a catamaran of cruising size that can self right unaided?

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Originally Posted by mark_morwood View Post
I think we may have done this topic to death. How about we change to another perennial topic that sounds good at first but has turned out not to be practical in cruising designs: main sheet fuses to prevent capsize. Here are a couple of websites to get people going:

Ganovelli Concept - Presentation ACS cruising

Syst?me anti chavirage UpSideUp

Mark.
Thanks Mark,

Keeping the shinny side up makes more sense.
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Old 21-05-2015, 11:46   #369
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Re: Is there a catamaran of cruising size that can self right unaided?

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Originally Posted by Juho View Post
Also gusts can flip a boat. Cruising cats don't just flip because of a gust. Unless you do something idiotic, it just isn't going to happen.

I mentioned also the possibility that the sea would right the boat. Crew might assist. And there may also be techniques that the crew can handle alone (no special technique in my mind at this point). Once over the weight and lever arm of the mast make it unlikely to just pop back up. No in storm conditions, the crew is not going to be able to right a cruising catamran.



Just wondering if five seconds fit in this "any length of time" category.
Quite possilby. Once on it's side the waves are now hitting the broadside of the exposed bridgedeck.


I'm not familiar with the design of all the catamarans. To my understanding it is typical that either hull is sufficient to carry the weight of the whole boat. If the hull is watertight enough, the hull might remain completely dry. I believe it is possible to make the hulls watertight enough to tolerate a 90 degrees turn to either side and back. You could design for this but thenn you have a far less functional boat for normal usage. Since it's not a likely scenario, it's not worth the tradeoff. Once over on it's side, waves can easily wash in any exposed openings.



If the boat design aims at tolerating a 90 degree angle, then water and fuel tanks should be built accordingly. I would not start the engine right away after the incident, but I'm sure the engine is not dead yet, especially if it was not running during the incident. If it can not tolerate 90 degrees while running, the boat manufacturer could design a switch that turns it off. There are techniques also for the batteries.
The boat is out off control and in danger, you are going to sit and wait to try starting the engine? Full tanks weigh a lot and in a violent roll to 90 degrees or more, the odds of something breaking loose is high. Now you are going to design a custom engine to tolerate operations to 90 deg? Lots of issues with your assumptions.


In some conditions the waves may break the boat, but in some other conditions that will not happen. It may also be that there are no big waves. If the boat turns back quickly, the probability of being hit by large waves in an unfavourable position decreases. A boat that is designed to survive 90 degree angles would be built stronger than a boat that is not planned not survive 90 degree angles. But in most (statistically unlikey to ever be an issue), the boat won't go over, so why design for it? If you make the boat capable of surviving the huge forces involved, it will lose a lot of performance and other desireable characteristics of catamrans.



I don't consider those two situations to be equally bad.
Run the numbers on the forces of a wave hitting the underbelly broadside and then come back.
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Old 21-05-2015, 11:52   #370
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Re: Is there a catamaran of cruising size that can self right unaided?

Quote:
Originally Posted by mark_morwood View Post
I think we may have done this topic to death. How about we change to another perennial topic that sounds good at first but has turned out not to be practical in cruising designs: main sheet fuses to prevent capsize. Here are a couple of websites to get people going:

Ganovelli Concept - Presentation ACS cruising

Syst?me anti chavirage UpSideUp

Mark.
Interesting that these yachtsman are seeking solutions to problems that don't seem to exist..

I am not sure sailing fuses are aggressive enough but step in the right direction.

if for instance this boat had a pivot arm released with a large bag on the end it is gonna go no where. Screenshot by Lightshot but race boats don't wana be overly delayed resetting such a big switch I'm guessing.
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Old 21-05-2015, 12:01   #371
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Re: Is there a catamaran of cruising size that can self right unaided?

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Originally Posted by paulanthony View Post
Beyond 90 degree aversion. See diagram.

The diagram was a tested technology on small craft that required manual deployment, however because the craft was small it could rely on a mast float to maintain the 90 degree stability that was needed whilst an articulating bowsprit ( that was able to swing back on a hinge like a gate because of the 90 degrees capsize ) be attached to a water bag and allowed to become effectively a crane lift arm.

This arm when attached to submerged bag was able to use the load of that bag as leverage to right the boat.

It did not translate to larger craft back then because.

A: There is no mast float to stop the boat going to 90.

B: Relates to (a) yeyond 90 the tech can not work(too late)

C: The bowsprit could not be engineered to double up as a crane as it could not be made strong enough and light lift to lift the bigger loads.

However 30 years later we have advanced censors and electronics which overcomes problem of (A) above because sensors can anticipate the boat going turtle before it does happen.

Secondly we have advance materials (carbon) that allow the use of a hinged crane under the bowsprit line instead of the bowsprit itself that can be fired back very fast on a trigger due to the mass of carbon is low.

Thirdly the carbon arm engineered as a back to back arch is able to provide the load capacity to lever upright a larger boat whilst being extremely light weight itself.

Put that all together and then you are possibly able to effectively deploy a large drag anchor automatically when you need it to keep the boat at 90 degrees.

I do not know the righting forces needed but one chap the other day said that to right a hobbie when totally inverted requires a 3rd of top side weight. So lets assume the boat is 10 ton then like for like you would need a 3 ton bag but at 90 and just beyond the balance point it would be far less and in fact a relatively minimal load is needed compared to the total boat weight to maintain near equilibrium balance point. Newton's first law of uniform of motion. The mass is trying to go down and not sidways.

There is not relatively a great deal of sideways pivot force at a static 90 degress. The forces come from the acceleration on the way over.

A ballast bag on the bow end of a rearward hinged arm when dropped would be in the water very fast as the boat would be moving over it from the hinge resulting in the bag being pushed down deep. The challenge faced though is about overcoming the forces acting on the brake(lever bag) when that deployment happens from a 10 ton boat scooting along at 10 knots. The other challenge is deployment when the craft is static as this would require the punching of that that arm into deep water to get the bag operational as quickly as possible.

It was a similar problem they had to overcome when emergency chutes were deployed from aircraft. Kept failing but they solved it.

Holding a boat at 90 does not require a lot of force. The forces that are being fought and controlled is inertia, wind and wave and sail.

The set up as a standard would seem capable of lending itself to most cat designs as the hinged arm simply needs to hinge just aft of the CG with the arm itself being no more than a double sided crane boom that terminates at the bow under the deck.

If you look at some of the carbon support arches now they support tons and weigh very little and the leverage force to hold a boat at 90 and drop a boat from 90 is very little.

The problem is not destroying the brake when it is deployed and trawled at a multitude of knots.

With today’s tech I do not think it is an overly complex nut buster to get this working. I hope there is success. The problem will be to make it cheap but I don’t think it presents such high cost either and we will probably start to see these first in flying hulls as any boat even those that fly are not good for business if they go turtle a lot and it also loses its fun factor after a while..

Works for pitch pole also.

I am quite sure we will start to see this tech coming through.

So if we scale up that picture, you are suggesting that cruising cats go over in 6" waves and 5kt winds?

That's a large beach cat. If you knew anything about scale design, you would know that you can't just increase the size of the parts and expect it to work.
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Old 21-05-2015, 12:23   #372
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Re: Is there a catamaran of cruising size that can self right unaided?

Quote:
Originally Posted by paulanthony View Post
Physics is physics. Toy boats are subjected to the same laws as big boats and big planes.

As things get bigger we see acting forces multiplied, square and cubed. The designers and engineers then match the resisting forces where possible with suitable materials. When we can't achieve spec we tend to wait for science to provide something new so we can continue the matching process and achieve scale later.

The laws of big physics are the same for small things as they are big things and humanity has never been put off by the challenge of big numbers and scale. What works for small things generally works for big things also and often big scale provides own its own advantage in overcoming problems.

This is why we have very tall buildings, planes bigger than football pitches and ships so big we need to build special ports to accommodate them.

With all that we have achieved if you really think that a solution can not be found for capsize aversion on a large scale then you are grossly mistaken. It requires one thing only. Will!

Shitty weather is a definable mathematical problem.
Whatever it is that you are ingesting, please let us know so we don't take the same! It obviously destroyed whatever logic you were born with...

I have the WILL for a $3M Sunreef Catamaran. When can I take delivery????
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Old 21-05-2015, 12:24   #373
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Re: Is there a catamaran of cruising size that can self right unaided?

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Originally Posted by DotDun View Post
Go read this story, citing first hand account of what happened.

Renegade Cruisers • View topic - Lagoon 38 capsize,

Is this use case supported in this conversation?
Experienced guys in a boat they were familiar with - and did not seem to have done anything wrong except may be head towards where they wanted to go to.

Could not happen according to previous posts.

But it does happen. And in this case for this particular delivery company two well founded cruising catamarans flipped within a few months of each other with loss of life in both cases.
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Old 21-05-2015, 12:31   #374
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Re: Is there a catamaran of cruising size that can self right unaided?

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Originally Posted by med View Post
Experienced guys in a boat they were familiar with - and did not seem to have done anything wrong except may be head towards where they wanted to go to.

Could not happen according to previous posts.

But it does happen. And in this case for this particular delivery company two well founded cruising catamarans flipped within a few months of each other with loss of life in both cases.
Hmm...you see nothing wrong with that picture?

So you have concluded that a monohull would have made it Annapolis???
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Old 21-05-2015, 12:41   #375
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Re: Is there a catamaran of cruising size that can self right unaided?

I'm lost? Is anyone saying a cat can't turtle or a mono can't broach, I think not. I thought it was about righting a knocked down cruising cat unassisted. I think it can be done when pigs fly.
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