15M Catamaran Capsize off Portugal

[Hardhead]

Trouble is, it seems 2 lane country roads are where a large number of the deer/vehicle collisions occur. I'd hit them on the corner if I could - but I could easily see my wife or elderly parents taking that advice and swerving far out of the lane and into a tree or traffic. I try to go noticeably slower around dusk and dark on such roads. I just realized this is a thread on a capsized catamaran... All concern for the sailors aboard, no matter what they sail.

[fxykty]

Originally Posted by owly

People who buy performance boats generally want performance, and are likely to push them to the limits, or at least very hard for that thrill of speed we all love. It is very likely that the cause of this disaster had to do with speed.. at least to some extent. ...

To be charitable, I will assume that you are speaking from ignorance and somehow transferring your highway driving experiences to sailing.

You, me, and everyone else has absolutely no idea how the crew were sailing that boat leading up to the incident. We can infer from their own report that they were reasonably conservative with double reefed mainsail in moderate conditions. Doesn’t sound to me like “pushing to the limits”.

You may not realise that one common reason people choose performance cruising boats (monos, cats and tris) is for their easily driven sailing natures. This means that a small sail area still propels the boat at speed, comfortably and without any pressing.

[Seaslug Caravan]

Originally Posted by fxykty

To be charitable, I will assume that you are speaking from ignorance

.......... performance cruising boats is for their easily driven sailing natures. This means that a small sail area .........

Is all thats required to capsize.

Fixed it for ya.

[Yihang]

Looks like a TS50 capsized in 2012.

https://www.bbc.com/news/uk-scotland...lands-19092243

TS 52.8′ | Christophe Barreau

[yvest]

Not any factual news on this one since the first articles ?

[XL2]

lots of speculation and road kill....
I hope they release the findings

[arsenelupiga]

Originally Posted by Seaslug Caravan

Is all thats required to capsize.

Fixed it for ya.

i thought you are performance cat frick?! Last thing i expect from you saying that lagoons are the best balanced boats possible considering performance, price, comfort and safety.

but yeah we all get smarter with age, so i should be prepared.

[jtsailjt]

Originally Posted by fxykty

You, me, and everyone else has absolutely no idea how the crew were sailing that boat leading up to the incident. We can infer from their own report that they were reasonably conservative with double reefed mainsail in moderate conditions. Doesn’t sound to me like “pushing to the limits”.

You may not realise that one common reason people choose performance cruising boats (monos, cats and tris) is for their easily driven sailing natures. This means that a small sail area still propels the boat at speed, comfortably and without any pressing.

You’re right that none of us know how the crew were sailing but as you said, even with prudently reduced sail, the boat will be propelled “at speed” so I don’t think we can yet rule out speed as a factor in this accident. I don’t know how fast these big cars sail but as speeds increase to well in excess of 10 knots with the boat planing on top of the water, the effect of hitting an object OR a wave is much different than in a displacement monohull at 6 knots. The increase in kinetic energy as speeds get higher can do some very powerful things to an object that would be impossible at lower speeds.

Hopefully we will eventually learn just what they hit (wave or whale or object) that caused this so we can all learn something useful and real, rather than having to guess at what caused this using the very limited info we now have.

[fxykty]

Originally Posted by Seaslug Caravan

Is all thats required to capsize.



Fixed it for ya.

Nope, you are not understanding. A performance cruising cat can use smaller sail area for more gust resistance with near the same average speed as if it used full sail area. A charter-type cat will require full sail area to generate the power necessary move at reasonable speeds, with a lower level of gust resistance.

In 20 knots AWS we can sail 90% upwind, 85% reaching and 95% downwind of our full sail average speed with a triple reefed main (34% of full mainsail area) and staysail (62% of full headsail area). That gives us a sail plan that can handle a steady 45 knots AWS and another 15 knots of gust response (though possibly the headsail will shred by then). That’s three times the current wind speed in gust resistance. Note that with 20 knots AWS we can use full sail areas in all wind angles.

For actual numbers, consider the following comparison of our Outremer 55L and a Leopard 48 taken from www.multihulldynamics.com.

• SA O55L 1297, L48 1555
• Disp O55L 11, L48 14
• SA/D O55L 24.5, L48 24.7
• SSpd O55L 23.0, L48 20.8
• KSI O55L 38.7, L48 35.0

SSpd is Stability Speed, which is the suggested abeam wind speed to begin reefing, allowing for a 40% gust factor.

KSI is the Kelsall Stability Index, which predicts abeam wind speed at which point the windward hull will lift out of the water (effectively the wind speed at maximum righting moment).

So, the heavier Leopard requires 30% more sail area for a similar sail area to displacement ratio. And the wider and deeper hulls (to support that extra displacement) do not have nearly the same speed ability as the lighter and skinnier (hulls) of the performance cruising cat.

Where it turns bad for the charter-type cat are the stability measures: almost 4 less knots to lift a hull and should reef 2 knots earlier. And imagine how much better the performance cruiser would appear when heavily reefed down and still sailing faster than the full sail area charter-type cat?

Looks like the performance cat is actually more stable than a charter-type catamaran using real world stability measures.

[fxykty]

Continuing a comparison of our Outremer 55L as representative of traditional high performance cruising cats to a TS50 as representative of higher performance racer/cruiser cats. www.multihulldynamics.com.

• SA O55L 1297, TS50 1615
• Disp O55L 11, TS50 7.4
• SA/D O55L 24.5, TS50 39.8
• SSpd O55L 23.0, TS50 15.2
• KSI O55L 38.7, TS50 25.6

But, can we really consider a TS50, or a Gunboat 55, or TS5, and other similar cats with sky high SA/D and very poor stability numbers, as performance cruising cats? Or are these actually racer/cruiser cats that shouldn’t be considered for short handed offshore cruising?

[Yihang]

Get caught with too much sail up and over you go though. As is with the case of the capsize in Skye. Once you get up to the TS5/TS50s it seems the margin of error is quite low.

[Yihang]

Originally Posted by fxykty

Continuing a comparison of our Outremer 55L as representative of traditional high performance cruising cats to a TS50 as representative of higher performance racer/cruiser cats. Multihull Dynamics, Inc. - Home.

• SA O55L 1297, TS50 1615
• Disp O55L 11, TS50 7.4
• SA/D O55L 24.5, TS50 39.8
• SSpd O55L 23.0, TS50 15.2
• KSI O55L 38.7, TS50 25.6

But, can we really consider a TS50, or a Gunboat 55, or TS5, and other similar cats with sky high SA/D and very poor stability numbers, as performance cruising cats? Or are these actually racer/cruiser cats that shouldn’t be considered for short handed offshore cruising?

Just saw that and It's good that we can admit there is a limit. I remember outremer saying they didn't increase the height of the mast on the 4X and 5X precisely for that reason.

Is there a SA/D calculator somewhere. I wonder what the current outremers have.

EDIT: found a calculator. the current outremer 45 has the same ratio as your 55L . Seawind 1260 is also not far from it. Interesting.
Maybe 24 is themagic number.http://www.nuomo.com/boatSadBruceCalculator.htm

[smj]

Originally Posted by Yihang

Just saw that and It's good that we can admit there is a limit. I remember outremer saying they didn't increase the height of the mast on the 4X and 5X precisely for that reason.

Is there a SA/D calculator somewhere. I wonder what the current outremers have.

EDIT: found a calculator. the current outremer 45 has the same ratio as your 55L . Seawind 1260 is also not far from it. Interesting.
Maybe 24 is themagic number.http://www.nuomo.com/boatSadBruceCalculator.htm

The SA/D for the 4x is 30.43 and the 5x is 31.1, according to multihulldynamics.
The performance numbers on our TRT 1200 are almost an exact match to the TS50 and is considered a racer/cruiser.

[Factor]

Originally Posted by Yihang

Get caught with too much sail up and over you go though. As is with the case of the capsize in Skye. Once you get up to the TS5/TS50s it seems the margin of error is quite low.

Cats very very rarely capsize sideways over, they are much more likely to pitchpole which gets into a whole different discussion on dynamic hull shapes etc.

[Yihang]

Originally Posted by Factor

Cats very very rarely capsize sideways over, they are much more likely to pitchpole which gets into a whole different discussion on dynamic hull shapes etc.

Yes, but with a SA/D in in the high 30s it seems a lot more likely. Which makes a lot of sense, we are talking 80% increase over a normal performance cruiser like an outremer 45. There has to be drawbacks.

Not trying to get into a cat capsize argument at all. Just trying to understand the limitations.