big performance cruising cat capsizes

[Franziska]

It makes me smile to see how people can start a stability discussion on this.
This was a boat driven hard in a race. Of course it can go over, be it with or without contribution of weather.
Of course a high powered performance boat has a higher risk.

It's crew is more likely to push it than the super careful owner of an undercanvased condomaran.

If you drive a Porsche you are probably also aware it does handle different than a Beetle or 2CV...

At the moment nothing points towards that there is anything wrong with the design.
If someone wants to take the higher risks it's their freedom and liberty to do so.

[Jim Cate]

And it depends on if you want to win a race and take risks or if you want to arrive safe and sail accordingly.

Gotta finish to win... in most forms of racing, balancing the degree of risk vs need for speed is a big factor. Some folks have the talent... Juan Fangio was an absolute master of extracting all of the performance available from a race car... had some expire on the victory lap.

But I believe that some cars and some boats have a broader range between goin' like hell and crashing. Maybe the edge is pretty narrow for Fujim?

Jim

[Polux]

Originally Posted by Jim Cate

.....

But I believe that some cars and some boats have a broader range between goin' like hell and crashing. Maybe the edge is pretty narrow for Fujim?

Jim

It is not a believe it is a fact.

Even on monohull that range exists in what regards SA/D (that is always bigger on a performance cruiser and even bigger on a racer) and makes a boat more easy or difficult to sail and control.

On a monohull that bigger difficulty on sailing makes it more prone to a knockdown. On a catamaran more prone to a capsize.

[Polux]

Originally Posted by Factor

Who told you that. Displacement-Beam-Sail Area is what you meant to say.

Your equation would suggest that a boat that weighs 10 tonne and has a HC to HC beam of 6 metres and has 10sq metres of sail is exactly as stable as a cat that weighs 10 tonne and has a HC to HC beam of 6 metres and has 100sq metres of sail. It is the sail area that acts as the lever. And in any event, racing cats rarely capsize, they invariably pitchpole. Some ugly outcome but the dynamics are different and need to be considered and managed differently. Maybe you should sail a few to gain some insight.

It is not my formula and if you don't know about that it is not even worth to discuss with you.

Sail area is sometimes considered but it has nothing to do with boat stability. It regards the sail area that a given stability can carry safely. But sail area can be reefed and boat stability remains the same with the boat with less or more sail area or even without any sail area.

[Factor]

Originally Posted by Polux

It is not my formula and if you don't know about that it is not even worth to discuss with you.

I know about it. Its just irrelevant.

Sail area is sometimes considered but it has nothing to do with boat stability. It regards the sail area that a given stability can carry safely.

Seriously? Sail area has nothing to do with stability? Seriously. Like I said, get out and sail a couple of boats - come back when you have some actual experience to draw from

[Factor]

Originally Posted by Polux

On a catamaran more prone to a capsize.

Again, few cats actually capsize, they pitchpole, and whilst the outcome is the same the cause and methods of mitigation are quite different.

[Polux]

Originally Posted by fxykty

Sigh, still conflating the concepts of static and dynamic stability and also not understanding that the shape of the righting moment curve is just as important as the height and f the curve.

In the first place, static stability only defines the height of the righting moment curve. Ignoring everything else, higher is better and your example makes sense only when ignoring all the other factors.

The shape of the righting moment curve describes the behaviour at higher amounts of heel. Typically a performance catamaran will have a lower maximum righting moment but a much wider range of positive righting moment (partly due to the higher SA/D). Hence, the performance catamaran can sail with a raised hull with a much lower decrease in righting moment than the heavier condo cat.

So at anchor a condo cat may withstand a higher gust from the side, but at sea while sailing the performance cat may handle higher wind loads.

And all this still ignores the dynamic stability factors, which favour performance cats. Taken to extreme, consider the cats and tris setting records while flying hulls around the world.

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.

[double u]

...the thing just saw itself in the mirror - & commited suicide! what an eyesore!

[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.

[Paul Kelly]

Never mind the theories of static and dynamic stability. This is all about seamanship. My father used to crew in races on a 30 foot Cat in the Mediterranean back in the 1970s. He told me that when the wind was up, they would always have one member of the crew looking astern. The moment one hull wake disappeared, they would ease the mainsheet.

And that particular Cat had a great big rigid buoyancy fitting at the masthead so she couldn't turn turtle if she did flip.

[akprb]

Performance and Cruising Cat in the same sentence. That's funny.

Well if it deters the incompetent from buying a cat more room for us :-)

[Dave Humphreys]

It is one thing in racing a sailboat to push the edge, take a risk if you will, but as a mono-hull sailor (R 26 & J 30) and racer for 40 years, my calculated risks sometimes didn't work out all that well. Rounding up, broaching, and broken equipment have been the result, sometimes. I have also owned a beach cat, (Prindel 16), lots of fun but never a cruising cat. I have pushed the edge on that little cat and found out what happens when flying a hull goes badly; its not nice! A cruising cat flying a hull and turtling is called a disaster not rounding up, not broaching, it is a disaster and quite possible life threatening. I have rolled a mono-hull and it righted itself (R 26). I had a mess on my hands but no real damage and after some clean up sailed home. I am suspect of a boat that incorporates an escape hatch in its bottom. Many love cruising cats, for me the term cruising cat is an oxymoron. They should be called condo cats and never leave protected waters. This post ought to ruffle some fur!

[Souzag818]

Originally Posted by Kentm

I needed the sarcasm font. I agree with you, it always seems to go the same way. I get it, I was joking (not very well science I’m explaining) every one makes their own choices for their own reasons.

Some/most of us got it. Others need to get a sense of humor and lighten up

[Franziska]

Yeah let's start the old battle again!
I prefer to be on an upside down multi over being 100ft under in a seaworthy sunk mono.

End of thread subscription from my end now.
Old horse beaten dead Dave.

[Cadence]

Originally Posted by Bleemus

Beauty is in the eye of the beholder. Maybe it looks better upside down?

You beat me to it. But beauty I guess has nothing to do with performance. She appears to be hard chined which seems unusual..