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Old 18-05-2015, 07:39   #166
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Re: Is there a catamaran of cruising size that can self right unaided?

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If we go by your recent statement that this thread is purely about being self righting, you are in the same position. Once it turns turtle offshore in a storm, there is no viable means to right it.

While I do find the proas interesting, when you start digging into them as cruising boats, they come with major compromises.
I said.. Perfect design .. "nearly" It lends its self to stability re-distribution after the flip better than a cat.

It could become self righting.
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Old 18-05-2015, 08:09   #167
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Re: Is there a catamaran of cruising size that can self right unaided?

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There is much debate about the new 'beamier' monohulls being able to recover from a 90+ degree knockdown.



For the same reason I don't wear a parachute on an airplane. Both needing a parachute while flying and capsizing a modern cruising catamaran are so statistically insignificant, it's a total waste of time.

And if such does happen, what guarantees your invention will work in whatever conditions caused the capsize in the first place???

This may be a fun mental exercise, but unless you design/build your catamaran with the highest priority requirement being recover from capsize, you waste lots of thought cycles better spent on learning how to sail (hint!).

Go forth and build/retrofit your catamaran with whatever invention you dream up. In 15 years when you're ready to shove-off, holler and we'll tell you the best destinations, as we'll have already been there!

A classic case of analysis paralysis.....
Planes that are susceptible to bad weather usually the small ones actually(similar to a cat of 40 foot and less) do have a defence. They have a parachute attached to the plane itself. Quite common now. They have refused to rely on the minimal probability of failure.

Those beamy hulls if they are ISA cat A will have a minimum stability vanishing point of around 130 and also negative buoyancy once inverted. They will be compliant in most cases to the current standards of mono stability. They deceive the intuition of the eye somewhat.
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Old 18-05-2015, 08:29   #168
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Re: Is there a catamaran of cruising size that can self right unaided?

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Great post.. Thanks.
Ditto!
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Old 18-05-2015, 08:50   #169
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Re: Is there a catamaran of cruising size that can self right unaided?

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With respect to capsize mono's are safer.. They can recover. I concur that a breached hull of mono will sink but my focus is capsize and not loss of displacement. - cats have won this battle.

Why would you not be interested in a cat that has capsize defence beyond the point of no return? Not sure why you would not want that.
The problem is they don't need a hull breach. An open hatch or companion way can and likely will take a boat to the bottom.
- In storm conditions, you are incredibly unlikely to flip a prepared cat. They have reduced sail and retracted the boards early as the storm is developing. They just don't flip that easily in that situation.
- If it's a sudden unexpected squall, odds are the mono has hatches and companion way open allowing it to quickly flood and go down.

I am interested in capsize defence but cats are intrinsically resistance to capsize, so they have a defence. If you look at the typical righting moments, cats are far more resistant to capsize of comparable monos. Monos are designed to be self righting because they are far more likely to go over. If the boat doesn't go over, there is no need for self righting and it's a waste of time, money and effort.

Do you have a ICBM armor on your boat? Most people don't because not too many people shoot ICBM's at cruising boats, so similarly, it would be a waste of time trying to protect against them. You can't protect against all possibilities, so you pick the ones that have reasonable odds of occuring and unless you are in a high performance racing cat or just an idiot, it's really hard to flip a modern cruising cat.

Still waiting on any documentation showing monos are safer.
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Old 18-05-2015, 08:58   #170
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Re: Is there a catamaran of cruising size that can self right unaided?

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I said.. Perfect design .. "nearly" It lends its self to stability re-distribution after the flip better than a cat.

It could become self righting.
Sure looks like it would be nice and stable upside down.

The idea that you will move a few thousand pounds of balast in storm conditions with the boat upside down is just ludicrous. Similar to traditional cats, your first and best defense is not to flip the boat. With monos you just hope not to go to the bottom during the inital knock down.

Interestingly, I believe the vast majority of commercial boats are NOT self righting. They put in far more miles in offshore conditions that a cruiser would wait out or otherwise avoid, yet when they've done the calulations and self righting boats were not the answer they came up with....hmmm...
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Old 18-05-2015, 09:29   #171
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Re: Is there a catamaran of cruising size that can self right unaided?

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Sure looks like it would be nice and stable upside down.

The idea that you will move a few thousand pounds of balast in storm conditions with the boat upside down is just ludicrous. Similar to traditional cats, your first and best defense is not to flip the boat. With monos you just hope not to go to the bottom during the inital knock down.

Interestingly, I believe the vast majority of commercial boats are NOT self righting. They put in far more miles in offshore conditions that a cruiser would wait out or otherwise avoid, yet when they've done the calulations and self righting boats were not the answer they came up with....hmmm...
This is true about commercial vessels. The compromise for self righting may not sit well with the intended task and may be cost prohibiting. Leisure wise I think we should have more choice.

With respects to the harryproa I found this.. I have not siffed through it yet though.

"To view the video, go to www.harryproa.com, then Designs/Racing/Solitarry and it is at the bottom of the page.

how much extra for the rig?

Not sure yet. As it is telescoping and we have not built one at this size, there may be some costs or savings we have not included in the numbers. The estimate is $30,000 if we built moulds for both parts. Be a few grand less if we use the bottom piece as a mould for the top one. Plus the sail. I'm still looking for a sailmaker with the right mix of imagination, willingness to experiment and suitable pricing.

A non telescoping tube mast would cost about $10,000.

having the tender double as an outboard sled is a brilliant idea. you should redo the movie and second image so people don't miss it.

A big tender with plenty of power makes exploration, rough anchorages, big payloads, water skiing etc possible. Also makes a much better liferaft, particularly if it has a rig and/or a solar panel and an electric outboard. I will change the drawing when I get the build plans complete.


how big would the tender's motor have to be help right the mother ship after a capsize?

Too many variables, but it would not be huge. In the very unlikely event of the schooner rigged cruiser capsizing (bendy masts, no extras, more than half the weight in the ww hull), the masts keep the boat floating at 90 degrees, with the mast heads upwind. Deploy a sea anchor from the leeward hull (the one in the water) and attach a tow line to the hull out of the water and tow downwind and it would not take much grunt to get it up as the waves and wind are both helping. May need to give some thought to launching the tender when the mothership was capsized.

The Solitarry in the video above is race oriented so much more likely to capsize (this will be one of the things we do deliberately as part of the sea trials). If the semi automatic righting (the mast can be canted to leeward and the big, buoyant boom immersed) doesn't work, we will add the tender to the mix.

rob"
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Old 18-05-2015, 09:58   #172
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Re: Is there a catamaran of cruising size that can self right unaided?

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Planes that are susceptible to bad weather usually the small ones actually(similar to a cat of 40 foot and less) do have a defence. They have a parachute attached to the plane itself. Quite common now. They have refused to rely on the minimal probability of failure.
And common = ??? 1%, 3%, 5% ?? I have to believe that 95+% of GA small aircraft do not have a parachute.

And I don't agree that all cats <40' are somehow extra susceptible to flipping in bad weather. Did you conclude this from insurance statistics also???

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Those beamy hulls if they are ISA cat A will have a minimum stability vanishing point of around 130 and also negative buoyancy once inverted. They will be compliant in most cases to the current standards of mono stability. They deceive the intuition of the eye somewhat.
Is this with full sails up and sheeted in tight? Load capacity = 100%?? 60kts wind pushing the rig in the water? 30' breaking waves? (all conditions that are likely during a knockdown!)
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Old 18-05-2015, 10:36   #173
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Re: Is there a catamaran of cruising size that can self right unaided?

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Several minutes is better than no minutes. The window of negative stability in modern mono's is around 90 degrees now. some even less at 60.



The fact they come back up saves life's and saves boats. It is not as terminal for the mono craft when inverted and they can be still fit for propose after where as the cat shifts its duty to that of being dedicated as a survival raft. I am not sure in this position they lend selves to the word "survival" much either and those that venture to sea with no life raft have a screw loose in my humble opinion.



I believe that designers and manufacturers could provide a lot more defence and recovery capability for cats but its not going to happen whilst every cat owner is willing to side with the manufacturer and echo their sermon and rely solely on the probabilities of a non event. I personally think this is the fools paradise. In less than 40 foot or even more you would not get me venturing to the fringes of season or geography on what is available now catamaran wise. - I would like more safety and ability to recover please Mr designer.

Since we've already determined that monohulls have a better chance of sinking than a catamaran flipping, shouldn't the builders of monohulls be designing some type of flotation so their designs don't sink?
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Old 18-05-2015, 10:45   #174
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Re: Is there a catamaran of cruising size that can self right unaided?

It would seem trying to argue either side must be by Don Quixote.
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Old 18-05-2015, 11:38   #175
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Re: Is there a catamaran of cruising size that can self right unaided?

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And common = ??? 1%, 3%, 5% ?? I have to believe that 95+% of GA small aircraft do not have a parachute.

And I don't agree that all cats <40' are somehow extra susceptible to flipping in bad weather. Did you conclude this from insurance statistics also???



Is this with full sails up and sheeted in tight? Load capacity = 100%?? 60kts wind pushing the rig in the water? 30' breaking waves? (all conditions that are likely during a knockdown!)
Wave height distribution is affected by wind so even if the smaller cat like for like is exposed to the same proportional sail loads as their big sisters the smaller cat then runs greater risk from the sea state which favours big cats over small ones. A 15 foot wave to 0 feet is a greater angle for a boat of 40 in length with a beam of 20 than a cat of 60 foot in length with a beam of 30. I think the current average significant wave height is about 10 foot so amongst that average expect to see some 20 foot waves according to wave science(quite exact) which I think is the approx beam of a 40 foot cat. Give or take. Wana go touring north Atlantic in a sub 40 foot cat? Be my guest but I would not do it.
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Old 18-05-2015, 11:50   #176
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Re: Is there a catamaran of cruising size that can self right unaided?

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Since we've already determined that monohulls have a better chance of sinking than a catamaran flipping, shouldn't the builders of monohulls be designing some type of flotation so their designs don't sink?
Maybe.. but that is not the question raised here.
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Old 18-05-2015, 11:54   #177
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Re: Is there a catamaran of cruising size that can self right unaided?

Can we keep this thread about anti capsize tech for catamarans. Some seem to wana turn it into a mono v's catamaran war. Best to keep those kind of passions for football.
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Old 18-05-2015, 12:08   #178
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Re: Is there a catamaran of cruising size that can self right unaided?

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Can we keep this thread about anti capsize tech for catamarans. Some seem to wana turn it into a mono v's catamaran war. Best to keep those kind of passions for football.
Then why do you start the thread by stating as "fact" that catamarans are more dangerous than monohulls without factual data to support it? If it wasn't your point to argue cat vs mono, why did you bring it up and repeatedly argue when people pointed out the flaws in your logic? I suggest in future threads, leave extraneous issues out if you don't want people to correct you on them.

As has been said a number of times by various people, you aren't going to self right a large cruising cat by yourself on the open ocean, particularly in the kind of storm conditions that could flip a large cruising boat just the same as you aren't going to raise a mono from the bottom in storm conditions by yourself.
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Old 18-05-2015, 12:11   #179
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Re: Is there a catamaran of cruising size that can self right unaided?

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Wave height distribution is affected by wind so even if the smaller cat like for like is exposed to the same proportional sail loads as their big sisters the smaller cat then runs greater risk from the sea state which favours big cats over small ones. A 15 foot wave to 0 feet is a greater angle for a boat of 40 in length with a beam of 20 than a cat of 60 foot in length with a beam of 30. I think the current average significant wave height is about 10 foot so amongst that average expect to see some 20 foot waves according to wave science(quite exact) which I think is the approx beam of a 40 foot cat. Give or take. Wana go touring north Atlantic in a sub 40 foot cat? Be my guest but I would not do it.
Why would you let yourself become abeam to a breaking wave large enough to capsize your boat with sails up, be it cat, mono, big or small?
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Old 18-05-2015, 12:22   #180
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Re: Is there a catamaran of cruising size that can self right unaided?

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Why would you let yourself become abeam to a breaking wave large enough to capsize your boat with sails up, be it cat, mono, big or small?
Coz some times they sneak up on you from other directions and it only takes one and if you make a mistake you kinda up the creak without the paddle with no second chances even a small one. Hence the title of the thread.
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