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Old 13-09-2017, 05:39   #121
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Re: Cats rarely flip ... Irma

It has just appeared to me that possibly there is a subversive psychological effect in place too.

Imagine you come into a cozy protected bay in the BVI. It is September and you find if full with dozens of charter cats moored neatly in clean, regular rows. All shiny and in perfect order.

A view like this could lull someone into thinking this is a perfect hurricane hole.

In fact, the charter company may have a special deal with their en masse insurer while the spot is a mouse trap and there is no proper hurricane hole within nearest 1000 miles (and the ones that there are, are full up with moored craft of all condition and, as such, no longer a safe hurricane hole).

There is no safe place in the hurricane belt in the hurricane season. People who believe otherwise are fooling themselves and should carry full insurance in case their roulette decisions turn against them. Given enough time, they will.

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Old 13-09-2017, 05:41   #122
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Re: Cats rarely flip ... Irma

add: anecdotal evidence is NOT proof to the contrary!
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Old 13-09-2017, 06:19   #123
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Re: Cats rarely flip ... Irma

Greetings and welcome aboard the CF, ixnax

Despite your reservations you did add (materially) to the discussion.
Thanks, also, to Just Another Sa.
These are interesting hypothesis, well worth pursuing.
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Old 13-09-2017, 20:34   #124
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Re: Cats rarely flip ... Irma

Wow. I see a de-masted Nautitech Open 40 in the middle I still would buy on the cheap.
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Old 14-09-2017, 01:03   #125
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Re: Cats rarely flip ... Irma

Well short term you may get some hurricane project cats on the cheap, in the long run the market for used cats may get overheated, a lot of potential ex-charter boats seem to be damaged in the Caribbean so the market could probably drain out a lot for years.
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Old 17-09-2017, 11:33   #126
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Re: Cats rarely flip ... Irma

The fact that so many cats flipped is revealing but to be fair a seemingly equal number of monohulls are sunk or half-sunk. My take is that the latter is likely due to the monohull drifting into something and grinding a hole into the boat. And we can see from many photos that also quite a few cats sunk or half sunk. Probably the result of hitting a submerged object, or another boat, and grinding a hold into the boat. That was probably more due to 15-30' waves washing into the mooring area than purely just the winds. In short, I don't think any ultimate conclusion can be drawn as to which boat design is better except that the insurance companies will all attempt to spread the risk by raising all of our rates, worldwide. Yes, even if you're not in a hurricane prone area, they will raise your rates too.

This was a CAT 6 storm. The weather planners will have to expand that scale. I have always said if at sea when a storm like this is barreling down on me, I will turn 90 degrees to it's predicted track and run out of the way. But that if I'm caught in one, I can survive up to a CAT 3 winds at sea using my sea anchor. Beyond that all bets are off. The boat will surely flip and hopefully become the worlds biggest life raft. If not for the winds, then surely the 40-50' breaking waves that would be generated as a result.

BTW, my buddies cat is at the bottom of that photo. Upright and fully in tact. He lucked out. I assume the damage will be minimal.

One thing I'd like to know is as these boats broke from the moorings, whether it was due to snapped mooring lines or failed cleats? I have been told that the first thing to fail in a hurricane of any great magnitude are the cleats pulling right through the deck under the extreme pressure of the surge.
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Old 17-09-2017, 11:47   #127
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Re: Cats rarely flip ... Irma

I have friends and clients who lost their boats and almost everyone associated with the Cruising community does, so sometimes that makes it hard to say this for the fear of sounding judgmental, harsh, uncompassionate or just being mean. But at the end of the day this is I believe one of the "Muy Importante" lessons to be learned from Irma. Once you come to terms with this fact of life, then you plan and act accordingly with your eyes wide open to what can happen because it's happened before.

It's just hard to not look at the carnage photos and feel sick to your stomach imaging your boat in that pile......sad for sure.

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Originally Posted by barnakiel View Post
There is no safe place in the hurricane belt in the hurricane season. People who believe otherwise are fooling themselves and should carry full insurance in case their roulette decisions turn against them. Given enough time, they will.
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Old 19-09-2017, 00:20   #128
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Re: Cats rarely flip ... Irma

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Originally Posted by donradcliffe View Post
If I was head a school of naval architecture specializing in catamarans, I would send teams down to the hardest hit areas immediately to gather as much data as I could. There are standardized calculations for transverse and longitudinal bare poles velocity for catamarans--the theoretical wind speed at which the a cat will flip with no sails up. By studying the designs and the mooring arrangements of the cats which flipped and the ones which did not flip, the school could validate or improve these calculations.

For instance, one of the pieces of data which could come pretty easily is whether any power cats flipped. Its pretty easy to calculate the bare poles velocity with and without a mast up. If the BPV is 50 knots higher with the mast down, I could see insurance companies demanding that masts be removed before a major storm.
Irma begs three questions:

1. What aerodynamic modifications in hull shape could help prevent a flip for a vessel on anchor or mooring riding out a cyclone?

2. What changes can quickly be made to prevent a flip?

3. Whether ballast would prevent a flip?

If vessels continue to moor in the path of cyclones these are natural questions which we should be asking.

It is the third question which has me most intrigued. Multihull owners loath weight forward, however, in extreme winds wouldn't a few thousand pounds of seawater be very useful?

I am thinking of floodable forward compartments which a fleet could easily employ when the big winds are coming.

All someone needs to do is open a valve and pump the compartment out after the danger is gone.
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Old 19-09-2017, 01:03   #129
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Re: Cats rarely flip ... Irma

For me the interesting point which I doubt we will find answers too is
- why are some of the cats upside down and others not ? Was it because of holes in the one hull ?

Why do some boats still have their masts and others not. This fascinates me the most ? Two boats next to each other one with a mast one without. Is it because of bad rigging ? Stronger mast section or what ?
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Old 19-09-2017, 02:06   #130
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Re: Cats rarely flip ... Irma

Quote:
Originally Posted by pbmaise View Post
Irma begs three questions:

1. What aerodynamic modifications in hull shape could help prevent a flip for a vessel on anchor or mooring riding out a cyclone?

2. What changes can quickly be made to prevent a flip?

3. Whether ballast would prevent a flip?

If vessels continue to moor in the path of cyclones these are natural questions which we should be asking.

It is the third question which has me most intrigued. Multihull owners loath weight forward, however, in extreme winds wouldn't a few thousand pounds of seawater be very useful?

I am thinking of floodable forward compartments which a fleet could easily employ when the big winds are coming.

All someone needs to do is open a valve and pump the compartment out after the danger is gone.
Asked already and answered too in this thread, see Cats rarely flip ... Irma and the next one lower down.

Short version:
1) select a boat with no rigid bimini.
2) select attachement points of mooring rope / anchor rode in such a way aerodynamic load resultant is inside them. 3 points allows this, one on each bow and one up the mast at a well supported point, like code0 halyard.
Make sure all fluctuation on loads effect mostly ropes to the bows, but not the mast, suitable elasticity of the ropes allows this. Won't work on tight anchorage with a lot of other boats.
3) No, it will make things worse when wind or boat change direction/orientation. And it will happen, just one other boat getting loose and hitting your boat will rotate your boat enough to cause flipping stern over bows (or diagonally) with bow ballast as both vertical lift and drag are very high in such case. And there is also problem with waves hitting windows, hatches and under the bridgedeck with a boat ballasted too deep.
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Old 19-09-2017, 05:22   #131
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Re: Cats rarely flip ... Irma

200+ mph winds, and about 1 in 10 cats were tipped over. Is this really a problem?

I've seen reports that between 50 and 80% of monohulls sank. Is that a problem?
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Old 19-09-2017, 05:33   #132
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Re: Cats rarely flip ... Irma

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Originally Posted by 44'cruisingcat View Post
200+ mph winds, and about 1 in 10 cats were tipped over. Is this really a problem?

I've seen reports that between 50 and 80% of monohulls sank. Is that a problem?


My thoughts exactly.
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Old 19-09-2017, 05:54   #133
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Re: Cats rarely flip ... Irma

This topic huuu, cat5 , anything can fly in those conditions, multis dont carry any ballast and then they can take off, but in any case monos are fukked to, there is any diference ?? no, no point at all.
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Old 19-09-2017, 06:00   #134
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Re: Cats rarely flip ... Irma

Those wind conditions are the very definition of chaos.

We humans love to seek patterns, try to make sense but. . .
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Old 19-09-2017, 14:48   #135
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Re: Cats rarely flip ... Irma

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This topic huuu, cat5 , anything can fly in those conditions, multis dont carry any ballast and then they can take off, but in any case monos are fukked to, there is any difference ?? no, no point at all.


In a Cat 5 Storm, 40 foot long steel boxes weighing between 4 tons empty and 30 tons loaded are picked up and thrown around like so much cardboard.

Must be about time to re-design the Aerodynamic shape and ballasting of a rectangular Corten steel box me thinks.

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