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Old 01-10-2011, 04:35   #16
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Re: 40' Required for Circumnavigation

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Originally Posted by dennisail View Post
Have you found any pics of inverted cruising yachts yet to add to your collection?
Don't have a collection - just googled "capsized sailboat". The results came back with 3 pictures of Volvo/AC-type racing cats and the rest were monos. Interestingly, a search for "sunken sailboat" just turns up monos.

Anyway, I was responding to the person who categorically stated that "A cats most stable position is upside down. A monohulls is right-side up..." He didn't differentiate anymore than that.

And going back to that google search thing - by far, the vast majority of pictures for both capsized and sunken boats were powerboats!

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Old 01-10-2011, 07:26   #17
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Woohoooo! Here we go again!

Ok, here a couple of questions....

A cat uses form stability to stay upright while a mono uses weight stability. Ok?

So when the mono sailors abandon ship and step up into their life raft, they are changing from their cherished weight stable craft to a form stable craft? In a gale? When their lives may depend on the stability of their newly- boarded craft?
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Old 01-10-2011, 08:11   #18
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This is more about personal preference than a true solution. There are facts and figures to support selecting lots of vastly different boats. You need to match what is important to you; how much space, water, sailing characteristics, etc. There are lots of boats I wouldn't go in but there are many both mon and cat that would be fine. You just need to know your boat and how to cope with bad conditions. I suggest you find a good teacher that owns a boat similar to what you purchase and work out how to hand things.
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Old 01-10-2011, 10:13   #19
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Re: 40' Required for Circumnavigation

I would say that, in the seagoing aspect, the size does matter. I would claim that the bigger boat is more seaworthy.

Imagine two similarly shaped / boats - similar hull form, ballast ratio, etc.. Now imagine one of them is 28' the other 32'. (e.g. Westsail 28 vs. Westsail 32).

When met with identical wave at identical angle - which of the two hulls is more likely to get capsized?

The smaller one.

We have only an X probability of meeting an Y sized sea wave. It is a function - the bigger the wave, the lower the probability.

Thus, the smaller the boat (all other factors equal) the bigger the chances (up to the point of certainty) of getting capsized on any extended offshore passage (where seeking refuge in a harbour is no longer an option).

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Old 01-10-2011, 10:22   #20
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Re: 40' Required for Circumnavigation

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Originally Posted by Jimbo485 View Post
(...) So when the mono sailors abandon ship and step up into their life raft, they are changing from their cherished weight stable craft to a form stable craft? In a gale? When their lives may depend on the stability of their newly- boarded craft?
Hehehe ! Bravo, very neat!

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Old 01-10-2011, 10:37   #21
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Re: 40' Required for Circumnavigation

It is so.
It is not.
My brother's going to beat you up.
Will not cause my brother's bigger!

Well, that was edifying. If nobody wants to actual help the OP understand the physics of the thing there can't be much reason to keep this open can there?

This is going to be the only warning.
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Old 01-10-2011, 10:43   #22
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Re: 40' Required for Circumnavigation

I have read that a wave that is 30% the size of the hulls length can capsize a monohull when the wave is on or close enough to the beam of a boat and breaking. A boat may survive the largest wave if it isn't breaking although when the sea is in a "confused state" there are other factors that can result in the boat getting into trouble. Pitchpoling in a following sea is another thing altogether.
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Old 01-10-2011, 10:58   #23
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LOL!

Ok, OP, here is the answer: IT ALL DEPENDS! Haha!

If you are a reasonable sailor, go for min 30', decent rig, good anchoring systems, trade wind RTW, hide during cyclones etc, there is a 99% chance you will get around fine. Go east around in the roaring 40s, smaller boat, cruise during cyclone season etc and you can lower that %. Go around in a bathtub and you will probably make it if you are careful.

Ask us now what you should look for in a lifetime partner!
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Old 01-10-2011, 13:54   #24
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Re: 40' Required for Circumnavigation

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Originally Posted by hummingway View Post
I have read that a wave that is 30% the size of the hulls length can capsize a monohull when the wave is on or close enough to the beam of a boat and breaking. A boat may survive the largest wave if it isn't breaking although when the sea is in a "confused state" there are other factors that can result in the boat getting into trouble. Pitchpoling in a following sea is another thing altogether.
I believe it was tank testing carried out by the USCG that determined the size of wave required to roll a vessel over beam on, was directly proportional to the vessel's beam.

Generally for a given length a cat will have considerably greater beam than a mono, so is less likely to encounter that wave.
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Old 01-10-2011, 14:08   #25
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Re: 40' Required for Circumnavigation

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Originally Posted by Factor View Post
Mythology mainly.
Some of The Myths:

Mono's are more stable. They are not. Cats have several times the righting moment for a similar length boat.

Mono's are self righting. MOSTLY they are not. They are less stable upside down than right way up, so the sea state that rolled them over will USUALLY right them. But not always. They (with only a few exceptions) do have some stability inverted. A truly self righting boat does not.

Mono's are more "seaworthy". The history of cats and mono's being caught in the same storms shows cats have survived when some mono's haven't. Probably vice-versa too.

There are many other myths - mono's sail better to windward etc - races show this to also be untrue.

Bigger is generally more likely to be safer, faster, more comfortable. But plenty of people circumnavigate in small multi's.
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Old 01-10-2011, 14:52   #26
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Re: 40' Required for Circumnavigation

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Originally Posted by 44'cruisingcat View Post
I believe it was tank testing carried out by the USCG that determined the size of wave required to roll a vessel over beam on, was directly proportional to the vessel's beam.

Generally for a given length a cat will have considerably greater beam than a mono, so is less likely to encounter that wave.
The formula I read was for length but only addressed monohulls.
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Old 01-10-2011, 15:17   #27
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Re: 40' Required for Circumnavigation

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Originally Posted by 44'cruisingcat View Post
Some of The Myths:

Mono's are more stable. They are not. Cats have several times the righting moment for a similar length boat.

Mono's are self righting. MOSTLY they are not. They are less stable upside down than right way up, so the sea state that rolled them over will USUALLY right them. But not always. They (with only a few exceptions) do have some stability inverted. A truly self righting boat does not.
Both of these statements seem to me to be pretty lacking in value.

A cat with its higher righting moment is less likely to heel but it capsizes at lower angles. The fact that it doesn't heel means that overpowering the sail is more likely to result in a capsize. Overpowering can also result in pitchpoling. That righting moment should help a mono beam on to a larger breaking wave as well.

Whether monos are "self righting" or not isn't the point. The point is will your boat recover from a capsize or not. A cat won't a mono might. If you are in waters where rescue is likely in a reasonable time that might make the cat the better choice because they are very stable upside down. On the otherhand if you are sailing into places where noone is likely to reach you in time it would seem to me that the chance that your boat will survive being capsizing or pitchpoling makes a mono a better choice.

People have sailed oceans in 18 foot monos. Has anyone done it in a Hobey Cat yet? There is something to this even it makes some of the multi owners insecure.
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Old 01-10-2011, 15:35   #28
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Re: 40' Required for Circumnavigation

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Originally Posted by 44'cruisingcat View Post
Some of The Myths:

Mono's are more stable. They are not. Cats have several times the righting moment for a similar length boat.
If you aren't going to differentiate between initial stability and ultimate stability, then you are just adding to the fog of myths. In general, a cat has greater initial stability than a mono. A mono has greater ultimate stability. A cat can be rolled by wind or wave. A mono by wave.
Quote:
Mono's are self righting. MOSTLY they are not. They are less stable upside down than right way up, so the sea state that rolled them over will USUALLY right them. But not always. They (with only a few exceptions) do have some stability inverted. A truly self righting boat does not.
I don't understand what you mean that most monos are not self-righting. If they don't suffer from down flooding, then most monos are self-righting in any weather that was large enough to capsize them in the first place.. A few of the more extreme race machines may not self right for a long time or at all
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Mono's are more "seaworthy". The history of cats and mono's being caught in the same storms shows cats have survived when some mono's haven't. Probably vice-versa too.
I don't know why you say 'probably vice-versa too'. It isn't probably, it is definitely. Look at the Queens Birthday storm. The fact that a boat was mono or multi was not a deciding factor. Length overall was a good predicator.
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There are many other myths - mono's sail better to windward etc - races show this to also be untrue.
Since we are talking cruising boats here, monos typically are significantly better sailing to weather. A dog overloaded poor mono design goes to weather like crap. An overloaded cat does too. A clean, modern mono cruising design goes to weather significantly better than a clean, modern cruising cat. Cats have lots of positives, sailing close to windward is not one of them.
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Bigger is generally more likely to be safer, faster, more comfortable. But plenty of people circumnavigate in small multi's.
Yep
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Old 01-10-2011, 16:04   #29
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Re: 40' Required for Circumnavigation

The following poem was written by Jo Djubal and I took it off the emultihulls website.

MONO TO MULTI

The weather is foul, the winds more than fresh...
Should we be this lopsided? Should we be in this mess?
Down below are the books and the clothes - plates galore -
in an abstract still life all over the floor ...
The meth stove swings crazy in a ludicrous dance,
to cook even water requiring a gymnasts stance ...
Aaaah - this is sailing ... this is fun ... this is sweet ...
and Hey, look how my heads almost level with my feet!
So the hours wear on and the heeling continues,
'till being skewiff seems almost not twisted.
2 minute noodles are dinner - formal,
and sideways on the head - well - isn't this normal?
Then on the horizon,
like a bird on the wing,
appears this strange vessel - this multi hulled thing ...
In no time it's passing - too stable, too quick-
and what's in that cockpit?
Are our Tascos playing tricks?
Is that really a table laid out with lunch?
Are those glasses free standing - without suction cups?
Is that guy in a deckchair? Is that woman asleep?
Is that guy on the helm in some new gimballed seat?
We stare somewhat awestruck at this boat without heel,
sailing too quickly shoreward like something surreal,
leaving us on our lean in the foam of their wake,
contemplating our world where nothing is straight ...
and although well in love with our classic, keeled mono,
the mirage of that multi seemed a dream fit to follow ...
... to sail smooth and stable in 20knt winds,
with the absence of even one gimballed thing ...
to relax back in deckchairs in a spacious cockpit,
- sundowners spared,
any murderous tilts ...
... Mono or multi ...?
somehow it seems plain ...
...in a world truly crazy,
and already askew,
to cruise at least upright,
seems the sane thing to do!
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Old 01-10-2011, 16:36   #30
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Re: 40' Required for Circumnavigation

Didn't the Polynesians populate the majority of the islands of the south Pacific using Multi Hulls?
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