New Gludy Video

The saloon roof is the floor and flooded but not flooded all the way.
The buoyancy built into the saloon roof is very high and water level is such that there is a small gap between the saloon floor and the water level.

Keep in mind that the floor of the saloon is well below hull top deck level so the upside down hulls would have to be submerged a long way to drown out the saloon.

This was one of my very early questions in the path to a multihull sailing boat.

There are no modern multihull sailing boats that i know of that have the full height bulkheads and nor do they need them. The foam sandwich hulls and saloon roof are very buoyant ... honest /forums/images/graemlins/ooo.gif /forums/images/graemlins/ooo.gif

It interesting that you started with the same questions that i did when I looked at these boats - maybe because I had just come from looking at the PC Power Multihull.
 
Do you mean that the saloon roof and the deck have enough buoyancy to keep the whole boat afloat, keeping the hulls almost completely out of the water, with no help at all from the additional displacement created by empty (or air-filled if you prefer) volumes?
If so, I must admit that I would have never expected that. Really impressive.
Ok, I'd still prefer to capsize with a battleship style, self-righting, multi-watertight compartments, steel monohull if I had to choose, but must admit that if it works as you say describe, it's not as bad as I would have thought.
Such characteristics would even lead to the conclusion that a life raft doesn't make sense! Well, maybe just in case of a major fire...
Do you know if they ever tested that with a decent size model, or even better with a real boat? Or is that just the result of their calculations?
I'm sure you'll see why I remain a bit skeptical...
 
Upside down the saloon roof sinks into the water(its itself is very buoyant) then before it even reaches the saloon floor both hull tops are into the water providing a great amount of buoyancy.
These hulls do not go far under before the sinking stops and you are now in the stable upside down position.

The hulls upside down a very bouyant indeed - even when flooded.

Its the hulls plus saloon roof that provide the buoyancy and yes - on a sailing cat the use for a life raft is when you have a fire.

On the video you will see the underside of the saloon painted orange - when upside down this is above the water and has to be painted orange by CE regulation.

You seem to be missing the order of sinking and in particular the fact that the wide hulls enter the water well before the floor of the saloon gets near.
 
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You seem to be missing the order of sinking and in particular the fact that the wide hulls enter the water well before the floor of the saloon gets near.

[/ QUOTE ]Nope, I got it. That's easily visible from the overall boat structure.
But I assumed that the saloon roof, the deck, and also the upper part of the hulls were just made of thick grp, whose buoyancy is very poor - if any (depending on the specific technique).
Considering what you said, I guess that all those parts are instead built in some sort of foam-filled sandwich.
Alas, you seem to have missed the last question of my previous post...? /forums/images/graemlins/wink.gif
 
The entire super structure is built of foam filled sandwich.
The boat is designed to float upside down no matter how badly holed hence blukheads all the way make no sense.

I know of no tests other than real live cases. The problem is that whilst I have found cases and images of early type cruising cats flipped I cannot find a single case of a modern one - it is very , very difficult to do.

Even the old ones floated upside down OK but lower in the water.Of course racing cats are a different animal.

One of my fears has always been hitting a container - Ellen Macarther did just that in her first big race and still managed to get in second place.

I have studied every documented major storm I can find and cats have done very well in all of them. They are easily IMHO the safest vessels to cruise in.

My flip over to a sailing cat resulted from me realising that with my planned MoBo cruising speed of 8 knots - I could probably cruise faster in sailing cat which can cruise safely at 15 knots if the wind is there and drink very little fuel when its not. Its easily the most stable shape at sea with minimal roll and is very, very safe.

I then asked the same questions as you have here.

Its the only boat which has both stable positions on the surface.
 
Agreed, speed and running economy are huge points in favour of sailing cats vs. long range displacement MoBos. The inherent propulsion redundancy (two engines and sails) is another one, not to mention that you can get much more boat for any given initial budget.
Not sure about stability=comfort, though.
During long passages it's not minimal roll that you want, it's regular/predictable roll.
I really don't think that a wide cat can beat a heavy stabilized monohull in terms of comfort, in anything but a flat sea.
 
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During long passages it's not minimal roll that you want, it's regular/predictable roll.

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Sorry disagree - ask those who have crossed the Atlantic in the trade winds in a tolling monohull - they have been rolled hundreds of thousands of times. I have watched crews desert on arrival!

In any event what wrong with a regular predictable roll of less than 1 degree?


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I really don't think that a wide cat can beat a heavy stabilized monohull in terms of comfort, in anything but a flat sea.

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I have had the heavy stablised mono and sure the stabilisation makes for much more comfort but it cannot beat the wide cat. /forums/images/graemlins/ooo.gif
 
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not to mention that you can get much more boat for any given initial budget.

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You can say that again ... I just wish I had waited another 10 days before forward buying my rand - it was a saving of £50k in just 10 days!!!!

Anyway the cost of a sailing cat is much lower than a MoBo - basically under half the price.
 
I see from your plan you are going to have a laundry up forward in the starboard bow, it is my understanding that the bows of cats need to be kept as light, and buoyant as possible, to alleviate hobby horsing and help prevent pitch poling. On my cat, only 37ft though, if a crew member walks out onto the bow, when under sail, the boat drops a knot in speed.
 
Mmmm... the subject has been debated at length, and you're surely aware that the least we can say is that there is no common consensus about the better comfort of cats. Surely, not when compared to heavy stabilized MoBos.
Personally, I've been out in a 45' or so diving cat (not a sailing one, but very wide - could easily accomodate some 30 divers and gear) in some short irregular waves, not more than 6 feet or so.
In the middle of the trip around the island, after half an hour or so, the helmsman had to enter a bay and leave a couple of divers on the beach 'cause they threw up anything they could, and their faces went all the way from violet to marble white.
Even myself and swmbo, both pretty used to some sea dancing, jumped into the water as fast as we could upon arrival, 'cause we couldn't stand anymore that cork-style, very irregular and unpredictable motion. Everybody onboard had to grab some rail all the time when standing.
Now, obviously I didn't have my boat handy to arrange a proper comparison, but knowing a fair bit of her behaviour I can safely say that I could have had a supper onboard with that sort of sea.
 
You are comparing a motor cat with a displacement motor boat; a sailing cat has a rather large stabiliser up in the air, sails. The motion of a sailing cat is nothing like a motor cat, which doesn’t have the motion dampening effect of the sails.
 
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I see from your plan you are going to have a laundry up forward in the starboard bow, it is my understanding that the bows of cats need to be kept as light, and buoyant as possible, to alleviate hobby horsing and help prevent pitch poling. On my cat, only 37ft though, if a crew member walks out onto the bow, when under sail, the boat drops a knot in speed.

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True but its a matter of scale.
This is a big cat and crew walking anywhere on it have no noticable effect. Also the washing machine is not right up front.
At the other end - the stern the same rule applies but so much buoyancy has been built in that you can have a large 15 foot rib with a massive engine.... if that is what you want. /forums/images/graemlins/ooo.gif
 
Mapism - as BigWow states - its very different on a sailing cat.

Its easier to get a clam out of its shell than have you take of your MoBo overcoat!! /forums/images/graemlins/ooo.gif

The corkscrew motion you talk about can be a very sickening experience - and it can occur on some badly designed cats. Although I think they are not as bad if used upside down! /forums/images/graemlins/ooo.gif
 
Yup, I'm aware of that.
On the other hand - other things being equal - a motor cat is bound to be bulkier than a sailing cat, and the weight also affects the inertia, thus reducing the "snap back" effect when riding the waves.
I accept that this is not enough to compensate the missing dampening effect of sails, but this effect is also inversely proportional to the beam, which is extremely wide in sailing cats.
 
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Its easier to get a clam out of its shell than have you take of your MoBo overcoat!!

[/ QUOTE ]Huh? I'm neither interested to defend MoBoers nor to keep any overcoat, what I reported was just a personal experience, fwiw. I've never been interested in religion debates (see my reply to bigwow for the other point).
 
More experience?
As of today, 'dunno exactly, but in the near future you'll have the opportunity to gain much more of it than myself, I reckon.
And I hasten to add that I'm getting greener with envy about that, as I'm typing!... /forums/images/graemlins/smile.gif
 
Just because I am retiring, albeit with a full video studio and broadband etc, to laze around the most exotic places in the world and never have to work again .... provides you with no reason to be jealous!!!! /forums/images/graemlins/ooo.gif /forums/images/graemlins/ooo.gif /forums/images/graemlins/ooo.gif

Besides which I plan to take you on a trip when we are around your part of the world just to give you a taste of my decadent live style.... then of course boot you off the boat - then you can be jealous!!! /forums/images/graemlins/laugh.gif
 
More than glad to accept the invitation, but mind, I could bring some of my best Sassicaia bottles for the trip.
And after some of those, it would be the first of us who fells asleep that could wake up with nothing but his lifejacket to keep him afloat... /forums/images/graemlins/tongue.gif
 
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