Catamaran Sinking

[44'cruisingcat]

Originally Posted by socaldmax

I would consider that to be a very dangerous area. Not only did those boats sink there for some reason (grounding, right?) but now there's the wreckage to possibly strike or get entangled with.

Pioneer bay is a place to avoid if strong north-easterlies are coming. It's wide open from that direction. And there are lots of boats moored there, many of which are basically left to their own devices in storms.

In the last few years dozens of boats have been wrecked there, quite possibly over a hundred, but generally they're all the same - boats left on moorings in the path of a cyclone, with plenty of warning it was coming.

Any wrecks that are in normally navigated area have been either removed or marked by now.

If you pay attention to weather forecasts, it's a safe area. It's NOT a cyclone refuge.

[socaldmax]

Originally Posted by Jim Cate

As it was secured to a mooring at the time, I believe that it went sideways... ie, a "normal" capsize. Post flipping, it dragged the mooring through the mooring field, striking and damaging several other boats. Sad for everyone involved.

Boats involved claimed that there were gusts to around 80 knots, sustained winds between 50 and 60. There was a lot of shore damage... roofs blown off, trees down, and one poor chap was killed in his car when a tree fell onto him. The Bruny island ferry (a biggish car ferry) was unable to operate and took refuge behind a nearby point. The storm was embedded in a well predicted cold front, and was only this intense over a fairly small path. We were about 75 miles west (in Port Davey) and only experienced 55 knots sustained, no thunderstorm activity when the front passed over us.

Cheers,

Jim

Wow! I wouldn't have thought that it would have enough windage to flip over like that! Surprising how much damage winds like that can cause, even though when I first read the wind speeds they didn't seem all that dangerous, but I guess they are!

[44'cruisingcat]

Originally Posted by DoubleWhisky

I think we all can agree for the following points:

1. Many cats can sink.
2. Some cats are really unsinkable.
3. Even some monos are unsinkable.
4. Any boat can be destroyed one way or another.
5. All discussions along the lines "cats do flip and monoss do sink" are nonsense.
6. Boat can be seaworthy having one or more hulls.
7. The safety on the sea is no matter of number of hulls.

I certainly agree with those points. But you only have to look at few a few threads here to see that plenty of people don't agree with points 6 and 7....

[s/v Jedi]

Originally Posted by DoubleWhisky

I think we all can agree for the following points:

1. Many cats can sink.
2. Some cats are really unsinkable.
3. Even some monos are unsinkable.
4. Any boat can be destroyed one way or another.
5. All discussions along the lines "cats do flip and monoss do sink" are nonsense.
6. Boat can be seaworthy having one or more hulls.
7. The safety on the sea is no matter of number of hulls.

Highly sensible post, almost got completely ignored, but true nonetheless !

[Factor]

Originally Posted by Jim Cate

A
Boats involved claimed that there were gusts to around 80 knots, sustained winds between 50 and 60. There was a lot of shore damage... roofs blown off, trees down, and one poor chap was killed in his car when a tree fell onto him.

Jim

I dont suppose you know what design it was? Or even the name of it? I would be interested to know more

[44'cruisingcat]

Pretty sure it was an Easy. Don't know the name though.

[Jim Cate]

Originally Posted by Factor

Jim

I dont suppose you know what design it was? Or even the name of it? I would be interested to know more

Sorry, I don't know either of those things. As I said, I wasn't there myself until a couple of weeks later. However, Sapient Sue, a new member of CF was there and was on the m/s that rescued Varg. She might have those facts available. I believe that it was a home-built craft, though... not that this has much bearing on things!

Jim

[sparau]

Originally Posted by Factor

Jim

I dont suppose you know what design it was? Or even the name of it? I would be interested to know more

It was a Snell Easy 37, owner build glass over ply construction ~4,000kg, sold after the incident via auction in May this year. I made a post at the time surprised at the event however the yachthub advert is gone so can't give name.

[DoubleWhisky]

Originally Posted by Jim Cate

And just to add some spice to the thread, did any of you hear about the 38 foot catamaran that flipped at its mooring in Little Oyster Cove, Tasmania in a thunderstorm last February? Not much publicity, but in front of many reliable witnesses! Several monohulls came to grief in that storm, and one, a recently launched reconstructed classic 8-metre named Varga was snatched from doom on the rocks at the very last moment by a stalwart yottie in a big motor sailor.

Something similar to Ormos Vlikho disaster, September 2011.

From one sailor's blog:
envoyinthemed.blogspot.com

Storm whipped through this bay killing one person aboard a yacht, causing significant damage to anchored boats, many of which were flung onto their beams, and resulting in 27 boats on the hardstand falling over. Winds of 90 knots (Force 11) were recorded during the approximate 45 minute duration of the storm, which was localized only to this particular bay. The wind flipped over a 37 ft catamaran, Sanyassa, trapping a 67 year old lady under the upturned hull. Ruairi Bradley, the owner of the Yacht Club, went out to the cat, dived below and rescued the lady, earning himself a Royal Humane Society Bronze Medal for Bravery. Ironically Sanyassa had completed a 14 year circumnavigation covering 54,000 miles and visiting 54 countries without major problems, only to be destroyed while safely anchored.

In reality the storm was not so localized, affected even Corfu, but the winds were mainly 50 - 60 knots. The patch of 90+ winds was only several hundred meters wide.
Cat (Prout?) was destroyed along with some monos. None were immune - one or two hulls.

S#!t happens, bigger boats were just pushed underwater in microbursts...

Tomasz

[a64pilot]

Mesoscale convective system, it's when several thunderstorms come together at once and winds etc. can be far more than expected.
We had one at Ft. Hood that destroyed many helicopters, broke chains and tossed Chinooks and Apaches around. Bad this is, you can't forecast them, yes you know bad wx is coming, usually a front, but it takes a life of it's own when more than one thunderstorm combine and you get very local, very bad wx and winds.

Damage at Ft Hood, $600 million
http://articles.latimes.com/1989-05-...rs-john-chapla

[Mirage Gecko]

44 cruisin cat are you near the VMR now we are anchored about a NM directly in front?
Chris

[Caribsailor]

Nepenthe, a 40 ft. Norseman was caught up in Hurricane Luis when it struck St. Maarten back in 1995. With a walk through hole in the hull, both bows and one transom gone she floated like this for a few months before being sold for the salvage price of $5k. Which turned out to be a real bargain as both engines were floating out of the water and undamaged. After some patches and paint she was sold some months later for $75k. I last saw her in Bequia, St. Vincent on sale with a new rig and sails for $260k. You might wonder how she could sustain so much damage. During hurricane conditions a cat at anchor will start swing back and forth in greater arcs until the diesels are used to bring it under control or she smashes into something. There were 1,200 boats in the lagoon during that storm so there was no shortage of boats to smash into. During Hurricane Omar, I spent hours working the throttles to limit such oscillations, as I was afraid they would jerk my anchors loose. Consequently, I consider anchoring in a hurricane hole as the last option I might chose to protect my boat. FYI, I went out to sea for Luis.

[Sea Frog]

From the above, I was able to figure out that I should stay away from smaller cats of less than 45'

[socaldmax]

In a case like that where a vessel has sustained severe damage, do they mark the title "salvage" or similar? I'm just having a difficult time imagining someone willing to pay that much for a vessel that was damaged so severely in the past.

[donradcliffe]

Originally Posted by 44'cruisingcat

No, not every cat. Or tri. Mine can't. The materials to build bare shell of my boat occupied three 1.2 x 2.4 metre pallets stacked 1 metre high.

So 8.64 cubic metres, just in the empty shell. Then there's at LEAST another 3 cubic metres of materials in the furniture and fitout.

Yet at launch the boat weighed 4.8 tonnes, partly loaded. We cruise at maybe 6.5 tonnes, maximum.

So it simply can't sink. Even in the unlikely event that every one of the 50+
sealed buoyancy compartments were flooded, the boat, on average, is simply not as dense as water.

And there are plenty of similarly built boats, which also simply cannot sink.

Originally Posted by 44'cruisingcat

Yes, and as I've repeatedly said, the materials to build my boat would occupy at least 12 cu metres. But still there are people here saying it would sink.

I'm now a little curious about the material volume. I just did a rough calculation, figuring that your boat hulls are 12 meters long, 2 meters high, roughly v-shaped. If I add 50% for the bridge structure/decking and assume one inch thick cored construction, I get about 3.6 cu meters, which would float 3.6 tonnes when awash.

This would explain why some cats are close to sinking, but others seem to float fairly high when holed.

If you put 8.6 cu meters into a 4 ton shell, it should float about half out of water when both hulls are holed. But does it really average over 2 inches thick, or are my estimates off??