big performance cruising cat capsizes

[fxykty]

Originally Posted by Polux

I don't have an idea of what you are talking about, the shape of stability curves are very similar between a performance cruising cat and a condo cat.

Static stability is a scientific concept a measurable one, dynamic stability is an important but it is a variable concept and one that cannot be measured.

For instance James Wharram considers: Static Stability x 0.6 = Dynamic Stability

But you are certainly wrong in saying that : "static stability only defines the height of the righting moment curve. "

Static stability mesures the energy that is needed to capsize a given boat and it corresponds to the area behind RM curve.

Your idea that a performance cat (size for size) is not less stable and therefore more prone to capsize than a condo cat is wrong and it can be dangerous if somebody believes you on a public forum.

Even if someone does not understand nothing about boat stability, it is factual and evident that:

1- there are hugely more condo cats then performance cats

2 - cruising cats that capsize are almost always performance cats on a huge proportion.

This should be enough to make people realize the stability diferences between the two types of catamarans.

Polux, I agreed with you that a performance cat typically has less static stability than a condo cat. Where I differ with you is that a well designed performance cat, just as with racing cats, will often have a flatter RM curve, and are therefore more tolerant of higher levels of heel. This does not mean, and I am not saying, that a typical performance cat is as or more stable than a condo cat, at low angles of heel.

Just to look at one factor that leads to a flatter RM curve for performance cats, the RM calculation includes height of centre of gravity (higher is less stable). By visible inspection a condo cat has a much higher centre of gravity than a performance cat, thanks to fly bridges, large generators in deck lockers, electric winches on cabin tops, larger tenders, etc.

Regarding number of capsizes, exclude all racing events (such as the one that started this thread) and the respective ratio of condo cat vs performance cat capsizes becomes much more balanced. And vanishingly small relative to the number of boats sailing the world’s seas.

Finally, the relative number of condo cats has nothing to do with stability and everything to do with chartering.

[picklesandjesse]

Originally Posted by Paul L

Ouch, that's somebody's baby.

Ugly baby !!! They should never have made love and given birth. Darwin is working here.

[Emouchet]

Someone forgot to push on the emergency button to free the main! Our may be, there was no emergency button!

[Skededel]

Having raced against many of these gents over the years I can pretty much guarantee that they were flat out pushing the boat. As I’ve now retired to a Lagoon 440 I think I can say that Greg is not thinking he should have bought a Lagoon!

[Simi 60]

Originally Posted by Paul L

Ouch, that's somebody's baby.

That only a mother could love

[billgewater]

A cruising catamaran? OK so where then is the large shaded aft deck cover that is largely mandatory in the tropics and/or the rain?.

However the vessel looks a tad experimental and is a certainly a bit different to the rather current collection of bland look alike staggeringly expensive plastic charter monsters.

It is essential that people put their ideas on the line so that we all ultimately benefit. Deep pockets required and some imagination.

Personally I am intrigued by the attempt to reshape the bow form. Most current cats must create enormous wind capture at the bows. Unless the cat is large, these enormous bows are not generally preferable for accommodation etc. Attempts were made earlier with bulbous protruding bow forms as seen on tankers, presumably to affect reserve buoyancy, water line length and stability. It seems to me that the shape on the cat is to allow rapid water shedding and lower bow wind exposure while retaining appropriate reserve buoyancy. It also looks like an attempt to reduce bow weight which seems like a good idea to me. Maybe it needs tweaking at the design level?
It also looks as though it could be built without recourse to moulds. Aka Warram designs.
It also seems that it carries a very powerful rig and was being pushed to the limit while racing. Do you all recall the America's cup challenge boat that actually folded in two and sunk? Pushing design and performance is expensive but faint heart .....

[Polux]

Originally Posted by fxykty

Regarding number of capsizes, exclude all racing events (such as the one that started this thread) and the respective ratio of condo cat vs performance cat capsizes becomes much more balanced. And vanishingly small relative to the number of boats sailing the world’s seas.

Finally, the relative number of condo cats has nothing to do with stability and everything to do with chartering.

Neither of the things are true:

The number of individually owned non performance condo cats is hugely superior to the number of performance cats by a considerable factor.

And regarding capsizes out of racing and regarding big cats the number of campsizes of performance cats is hugely superior to the capsize of condo cats even if they are less, by a factor. You should know that and I don't want to give examples here.

Some have the wrong idea that I am against cats or even performance cats that is not true and if I owned a cat I would have a performance one but that does not mean that I don't know the difference between them the advantages and disadvantages.

While you can have a relatively small offshore condo cat with 36 or 38ft and have a reasonable safety factor that is not possible if it is really a very light performance cat. Performance cats need size to have a bigger beam and that way compensate in stability for their lightness. That's why most of them are are 44ft or over....and even so you see from time to time 50ft performance cats capsizing (even bigger) and not only racing.

I don't know if any condo cat with 50ft or over that has ever capsized but if so it is so rare that I never heard about it.

[Kerry1]

Originally Posted by fxykty

For a larger cat it is a much more complex than just angle of heel. Check out UpsideUp http://www.oceandatasystem.com/references/en. Seems like a reasonable albeit pricey safety solution. Can anyone provide first hand experience?

I saw the 12 point monitoring systems mentioned on the Sunreef cats, is that what you refer to? What about an immediate release system of the main sheet, and a backup sheet that is used to regain momentum and prevent sail flogging? If the mainsheet is released before the irreversible critical righting moment specified for the boat is reached that's problem solved isn't it? I guess more sensors that measure the seaway, yawing, overall attitude of the vessel gives more accurate info upon which to act and a speed advantage. Seems to me that all that stuff can essentially be had in the microcontroller of a cheap self levelling, hover-on-the spot drone these days.

Ok, I read a bit more of that webpage, and it seems they all had "a complete UpSideUp solution installed" so someone is already doing this. Probably be standard issue on these things one day soon. I had a look at the picture and the whole system seems to use load cells and other sensors to read the pressures on the vessel. Thing is it may tell you when to back off, but it doesn't seem to actually trigger any release, unless I am mistaken. Hard to read the item headings. The reason pilots will put the landing process in the hands of their flight computers in adverse conditions is because the computers respond quicker to external influences on many fronts. Our own reactions are regrettably too slow. Still even with this fitted may have saved a lot grief let alone loss of life.

[Bleemus]

Just my opinion but the reserve bouyancy in the bows of that boat was compromised by the design. Wouldnt surprise me at all that was a contributing factor in digging it in and flipping.

[Bleemus]

Originally Posted by Kerry1

I saw the 12 point monitoring systems mentioned on the Sunreef cats, is that what you refer to? What about an immediate release system of the main sheet, and a backup sheet that is used to regain momentum and prevent sail flogging? If the mainsheet is released before the irreversible critical righting moment specified for the boat is reached that's problem solved isn't it? I guess more sensors that measure the seaway, yawing, overall attitude of the vessel gives more accurate info upon which to act and a speed advantage. Seems to me that all that stuff can essentially be had in the microcontroller of a cheap self levelling, hover-on-the spot drone these days.

Ok, I read a bit more of that webpage, and it seems they all had "a complete UpSideUp solution installed" so someone is already doing this. Probably be standard issue on these things one day soon. I had a look at the picture and the whole system seems to use load cells and other sensors to read the pressures on the vessel. Thing is it may tell you when to back off, but it doesn't seem to actually trigger any release, unless I am mistaken. Hard to read the item headings. The reason pilots will put the landing process in the hands of their flight computers in adverse conditions is because the computers respond quicker to external influences on many fronts. Our own reactions are regrettably too slow. Still even with this fitted may have saved a lot grief let alone loss of life.

These systems always make me laugh. I raced in the '94 Twostar race on a 40 foot racing trimaran. When the **** hit the fan you always had the mainsheet in your hand in case you started to bury a bow. Look at all the components of that system that can fail. Pathetic attempt to market to the unknowing.

[boatman61]

From where I sit one can manage the sail well enough to maintain the fine edge.. even through a small gust..
The catastrophic moment comes not via the sail as such.. more when a small cross wave can alter the wind effect/angle beneath the boat and once that lift is emphasised all is lost.. if you think about it.. the further a boat leans the greater the wind deflection on the sail.. and the greater the wind pressure build up under the hull where it has a solid surface to push it upwards in the form of the lee hull.
But hey.. I'm just chucking balls in the air..

[contrail]

Originally Posted by Polux

Neither of the things are true:

The number of individually owned non performance condo cats is hugely superior to the number of performance cats by a considerable factor.

And regarding capsizes out of racing and regarding big cats the number of campsizes of performance cats is hugely superior to the capsize of condo cats even if they are less, by a factor. You should know that and I don't want to give examples here.

Some have the wrong idea that I am against cats or even performance cats that is not true and if I owned a cat I would have a performance one but that does not mean that I don't know the difference between them the advantages and disadvantages.

While you can have a relatively small offshore condo cat with 36 or 38ft and have a reasonable safety factor that is not possible if it is really a very light performance cat. Performance cats need size to have a bigger beam and that way compensate in stability for their lightness. That's why most of them are are 44ft or over....and even so you see from time to time 50ft performance cats capsizing (even bigger) and not only racing.

I don't know if any condo cat with 50ft or over that has ever capsized but if so it is so rare that I never heard about it.

Well, since I am intimately familiar with cruising cats, and sailing them, I can actually name a few such instances, but it will probably do more for your knowledge base if I leave you to google for them.

Cheers,
Tim

[waterman46]

Originally Posted by Franziska

Polux, you nailed it with the last phrase. It's a choice. And it depends on if you want to win a race and take risks or if you want to arrive safe and sail accordingly.

Sail accordingly, like, reef the thing down in wind over 10 knots and hope you never get hit by a gust?

Those pictures show all those cats flying a hull in very moderate sea conditions, where it appears wind must certainly be less than 20 knots. So how can you fly a hull ( which is like balancing an egg on its small end and keeping it from rolling over ) in such moderate wind even with full sail on her?

I have to conclude its a very dangerous design for cruising shorthanded.

[alansmith]

Originally Posted by Ivansgarage

You have never been sailing until you take an 18 foot Hobie Cat
Jibe-Ho and say Jibe-o-**** stick it straight up on its bows and you're
on the ass-end holding on for dear life. Still got the scars from falling
through the rigging.

Now that is Fun.

Ivan, dude, u cracking me up....been there and done that...one of those "ah, sh!t" moments.

[alansmith]

They had competent crew on board. Sometimes...we stupid men...we just gotta see what that baby will do. Now they know. I tell you one thing...You don't come away from this disaster without a big ouch in the pocket book. I hope it doesn't destroy the designer. Personally i have always lusted after a performance cat. But i don't have those kind of finances. Then again i keep writing letters to Penelope Cruz...but i am pretty sure Javier Bartem keeps intercepting them. Why else wouldn't she respond to my meows?