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Gludy 12-07-2008 04:27

Sinking Cats
 
Modern well designed cats as I understand it do not sink - they float upside down.

I have just heard of a cat sinking on the way to the Caribbean last year when the mast punched a hole in the cat and it sank - does anyone know of other cats that have sunk?

GordMay 12-07-2008 04:40

Like ANY boat, Catamarans can (& have*) be sunk - usually when “holed” in some manner.
Capsized Catamarans tend to remain floating upside down.

For recent stories, search catamarans:
SAMPSON
CATANOVA

ssullivan 12-07-2008 05:02

Unless you have watertight bulkheads, fully enclosed in many areas that are not compromised, any boat can sink (whaler types made of foam excepted).

Factor 12-07-2008 05:03

Quote:

Originally Posted by GordMay (Post 181770)
Like ANY boat, Catamarans can (& have*) be sunk - usually when “holed” in some manner.
Capsized Catamarans tend to remain floating upside down.

With respect that should read SOME catamarans,

My multi wouldnt sink if you cut ten holes in the bottom of it.

Bagatelle (crowther) hit the bricks and destroyed half of one hull and stayed afloat

A madman tried to scuttle his own Factsback 43 eroica, it floated in spite of his efforts

GordMay 12-07-2008 05:22

Quote:

Originally Posted by Factor (Post 181776)
1.With respect that should read SOME catamarans,
2.My multi wouldnt sink if you cut ten holes in the bottom of it...

1. With respect, I'll grant that I might have said "virtually" all ...
2. Captain Edward J. Smith was of the same opinion regarding his vessel ...

JusDreaming 12-07-2008 05:28

I was told by a coast guardsman that when they found abandoned catamarans they could not sink them. They would shoot them with their guns but could only get them to sink to the gunnels. They would blow the cabin off. but they just sink to where they were level with the waterline

exfishnz 12-07-2008 05:30

Quote:

Originally Posted by Factor (Post 181776)
My multi wouldnt sink if you cut ten holes in the bottom of it.

Really??? What if you cut ten holes in each hull? :)

Whimsical 12-07-2008 05:43

Depends on what it is made out of.
Take mine for example. The cored panels alone displace over 7 ton while the loaded displacement is only 6.5 ton. This is without taking into account any sealed boyancy chambers of which there are many.

Mike

Gludy 12-07-2008 05:53

All interesting stuff but how do you find out if the cat you are looking at can be sunk other than asking for comments from the dealer?

cat man do 12-07-2008 06:01

Quote:

Originally Posted by Gludy (Post 181799)
All interesting stuff but how do you find out if the cat you are looking at can be sunk other than asking for comments from the dealer?


Go out and punch holes through the bottom;)

Dave

Gludy 12-07-2008 06:10

GordMay
"recent stories, search catamarans:
SAMPSON
CATANOVA"

Both your examples were powered cats with heavy engines/gear etc.
I am talking about sailing cats

Whimsical 12-07-2008 06:14

Quote:

Originally Posted by Gludy (Post 181799)
All interesting stuff but how do you find out if the cat you are looking at can be sunk other than asking for comments from the dealer?

Custom boat and talk to the designer.

Mike

maxingout 12-07-2008 07:59

I know of a chartered Privilege catamaran in the Caribbean that had a hose failure on a through hull. The charterers abandoned the catamaran because water was coming into the hull. They actually got on board a ship who "rescued" them. The charter agency knew the boat could not sink, and they found out where the boat was abandoned from the charterers, and they sent a recovery boat out to find the catamaran.

When they found it, the Privilege was motoring in circles with water up to a person's calf in one of the hulls. They fixed the leak, pumped the water out and returned it to charter base.

That's one of the reasons I brought my Privilege 39. I wanted a boat that was extremely difficult to sink.

BigCat 12-07-2008 08:15

Floatation and multihulls
 
The BigCat 65 structure has about 450 cubic feet of displacement in its structure, that is, if you add the thickness of all the structures, most of which is balsa cored. That's 28,800 pounds of floatation. I would think that it is probably typical in that it could easily sink to the point of being more or less awash. It has a lot of tankage, but that tankage is pretty close to neutral in buoyancy if the tanks are full. I think that to reliably float high, multihulls should have some sealed compartments or floatation (2 pound density polyurethane) foam. One cubic foot of foam will float 62 pounds of weight. I would think that most catamarans would float well upside down because they have a lot of trapped air inside of them. However, if you start cutting holes in the bottom because you are offshore and need access and shelter, you are in some jeopardy of sinking., or at least floating rather low.

My advice is to add a bunch of foam. The BigCat 65 uses crossbeams which I am filling with foam, and I am filling the one foot thick bridgedeck with foam, too. This is enough foam to float the boat fully loaded, and is in addition to the roughly 29,000 pounds of floatation in the structure. If upside down, the BigCat 65 should float with the bridgedeck above the water. We have discussed all of this before, I think a lot of it is under the thread about liferafts. You are adding 16 pounds of foam per 1000 pounds of floatation to your boat, but it is worth it to me.

cat man do 12-07-2008 08:20

There was a 40 ft Brisbane cruising cat that flew a hull and the leverage on the daggerboard tore a large section of hull away,

That hull filled with water and drowned the motor on that side, but they still got her back to port under her own power.

Dave


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