Cats rarely flip ... Irma

[Polux]

Originally Posted by donradcliffe

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.

That makes sense. More then a decade ago I remember a transat where several big ocean racing catamarans where capsized in bare poles. It turned out that their wing masts would generate a capsizing moment over 70K winds, no matter waves. After that they modified the masts and give the boats more stability. I don't know know what will be the wind that capsizes them but surely hurricane winds will do the job.

This new increase of abnormal conditions (or normal but stronger ones) pose a new defy to monohull cruising designers.

Recently I was kind of racing with a 50ft cat when I saw black clouds coming with nasty seas. I took two reefs on the main and deeply reefed the genoa, the cat did not reef. The wind passed from 15k winds to 45k winds on a moment along with nasty seas.

I had to turn on the wind and with the boat deeply heeled took out the main (from the cockpit) and reduced the genoa to a tiny piece of sail. Even only with the small front sail I was going at 12.5k.

When I resumed sailing I saw with concern that the cat was unable to take out the main (probably afraid to turn on the wind due to capsize risk) and was going at speed right in direction of an Island (Hydra) unable to change direction, taking the wind almost directly from the back. Any other direction would increase capsize risk with that huge amount of sail up.

I was seeing a lot of guys trying to pull the sail down but it took a long, long time and they were already very very close to the Island when they succeed (I was really concerned).

The fright was so much that they took out the sails completely and proceed with the engine.

[mikedefieslife]

Originally Posted by john61ct

funny, not. . .

I think many insurance companies will go under, be unable to pay out

And fewer will offer such coverage at all, or maybe just at rates untenable except for the silly-rich

I severely doubt that. I bet the vast majority of boats are backed some of the largest insurers in the world such as Allianz Global and the like, then resold or packaged on various markets.

[Bean Counter]

It is likely the same underwriters eg LLoyds and the rest of the sub underwriters will be up for not just the boats, but land based damage too and maybe the odd airplane. We all pay significant premiums for events like this, hurricanes, tsunamis, etc. My own insurance for the Caribbean is more than double for the med. I recall an insurance policy that if in a hurricane zone, the mast should be unstepped (any boat) and stored securely and the boat should be strapped down. If the mast is not unstepped it should be secured by lines to ground anchors. I noticed in the drone view of Nanny Cay a number of strapped down boats that still fell over. Maybe the straps busted.

[Falbala60]

I would like to learn for the FUTURE from this exceptional (I hope!) hurricane.

Some questions :

In Nanny Cay...

https://www.youtube.com/watch?v=keCJwQsKBh0

thank you "Bored At Work" for this so fine video., it should help to understand !

On this video, in the beginning, on the opposite side of the bay, you can see 4 or 5 catamarans that seems arrived there the "day after", they look perfectly intact, all their lines and springs OK... but one sinked on the right.

Question 1 : What the manager or owners did for those units to withstand the hurricane so well ? They had the same hurricane as the others piled up 100ft apart ! Look like no hurricane for those.

At the end when the drone shows the boatyard, there are maybe 10 catamarans also in supposed pristine condition. You can see their tie-downs... but some does not show any.

Question 2 : This boatyard is approx 5 to 6 ft, OK say 10 ft max (I already chartered there), above sea level, and as the storm surge évaluated at 20ft+ came, the water depth with big waves should be at 12ft... and then those looking fine catamaran should float and rock with the waves...
is it possible for tie-down to keep a catamaran from floating, and if so they should be full of water ?

[NoahTreat]

Originally Posted by Falbala60

I would like to learn for the FUTURE from this exceptional (I hope!) hurricane.



Some questions :



In Nanny Cay...

thank you "Bored At Work" for this so fine video., it should help to understand !



On this video, in the beginning, on the opposite side of the bay, you can see 4 or 5 catamarans that seems arrived there the "day after", they look perfectly intact, all their lines and springs OK... but one sinked on the right.



Question 1 : What the manager or owners did for those units to withstand the hurricane so well ? They had the same hurricane as the others piled up 100ft apart ! Look like no hurricane for those.



At the end when the drone shows the boatyard, there are maybe 10 catamarans also in supposed pristine condition. You can see their tie-downs... but some does not show any.



Question 2 : This boatyard is approx 5 to 6 ft, OK say 10 ft max (I already chartered there), above sea level, and as the storm surge évaluated at 20ft+ came, the water depth with big waves should be at 12ft... and then those looking fine catamaran should float and rock with the waves...

is it possible for tie-down to keep a catamaran from floating, and if so they should be full of water ?

I live in the Central USA (Arkansas) in what they call tornado alley. And the smallest of small tornadoes F1 is winds from 73-112 mph. I've seen an F4 winds 207-260 mph completely destroy one house and the house next door still has a shingles on its roof.

While these are great questions, you will probably find that those cats did nothing different than the one next to it that sank or flipped over.

[SV THIRD DAY]

How they always land on their

https://youtu.be/RtWbpyjJqrU

oh....not those cats

[Steadman Uhlich]

Regarding the question up above about the four cats that are on the opposite side of the small bay from the boats that were destroyed:

You asked what was different, and why those boats seem unaffected.

Notice they are on the OPPOSITE side of the bay from the boats that are piled up on one another. And notice the general direction of the boats and masts of the boats that were piled up.

Notice the "safe" cats are at the base of a relatively high mountain.

Notice there are several multistory buildings near the "safe cats", near the water's edge.

I suspect those few boats were relatively sheltered from the wind, because of the position in respect to the buildings and mountain. In short, they could have been in a "wind shadow" location.

[SecondBase]

I've enjoyed many charters on cats and own a monohull. I like both because I enjoy sailing.

People first and property second both during the storm and as a recovery priority.

I don't intend this as a statement against cats and I know they are very popular, roomy, twin-engined, fast and convenient. The question I would ask is

-- What would John Vigor do? --

A choice to sail a boat through a survival storm - cat or monohull?

A choice to anchor a boat through a survival storm - cat or monohull?

I don't mind a genuine debate on seaworthiness. If that's what we're having then it starts with John Vigor's criteria.

On the other hand, if someone said 99% of cat owners have no interest in sailing thru a survival storm I totally get that. And I stand with them as the eye readies to roll by 60 miles away from me.

-

One lesson learned may be the addition of Kevlar storm skirts to cats stored on land as part of a better standard strap down. These run 360 from toe rail, bow, stern and are staked out to ground. Blocking the wind from flipping. We would see these show up for mega cat storage first - as early as next season's layup.

Another lesson may be deliberate flood compartments forward for cats left in the water to weigh down the bows while moored. Maybe using air bags as "water bags". These same compartments would protect when hitting a container under sail. 500 gallons of water in each bow would reduce windage and change the airflow into a downforce on the cat roof instead of an upforce on the bridge deck.

Third option is a travelift that can flip and store cats before the storm. 65 foot boats do get safely rotated every day.




Not saying any of those are even feasible but all options should be explored by those more knowledgeable than me.

[smj]

Originally Posted by SecondBase

I've enjoyed many charters on cats and own a monohull. I like both because I enjoy sailing.

People first and property second both during the storm and as a recovery priority.

I don't intend this as a statement against cats and I know they are very popular, roomy, twin-engined, fast and convenient. The question I would ask is

-- What would John Vigor do? --

A choice to sail a boat through a survival storm - cat to monohull?

A choice to anchor a boat through a survival storm - cat or monohull?

I don't mind a genuine debate on seaworthiness. If that's what we're having then it starts with John Vigor's criteria.

On the other hand, if someone said 99% of cat owners have no interest in sailing thru a survival storm I totally get that. And I stand with them as the eye readies to roll by 60 miles away from me.

-

One lesson learned may be the addition of Kevlar storm skirts to cats stored on land as part of a better standard strap down. These run 360 from toe rail, bow, stern and are staked out to ground. Blocking the wind from flipping. We would see these show up for mega cat storage first - as early as next season's layup.

Another lesson may be deliberate flood compartments forward for cats left in the water to weigh down the bows while moored. Maybe using air bags as "water bags". These same compartments would protect when hitting a container under sail. 500 gallons of water in each bow would reduce windage and change the airflow into a downforce on the cat roof instead of an upforce on the bridge deck.

Third option is a travelift that can flip and store cats before the storm. 65 foot boats are rotated every day.


Attachment 155784

Not saying any of those are even feasible but all options should be explored by those more knowledgeable than me.

This guy has extensive experience with both mono and multi.
http://www.yachtingworld.com/skip-no...wins-out-70549

[44'cruisingcat]

Originally Posted by SecondBase

I've enjoyed many charters on cats and own a monohull. I like both because I enjoy sailing.

People first and property second both during the storm and as a recovery priority.

I don't intend this as a statement against cats and I know they are very popular, roomy, twin-engined, fast and convenient. The question I would ask is

-- What would John Vigor do? --

A choice to sail a boat through a survival storm - cat or monohull?

A choice to anchor a boat through a survival storm - cat or monohull?

I don't mind a genuine debate on seaworthiness. If that's what we're having then it starts with John Vigor's criteria. .

When it comes to multihulls, what does John vigor know? I mean, what actual experience does he have? I read one of his books years ago, and the impression I got was his absolute certainty that the ONLY way to successfully go cruising was HIS way. In an old wooden ketch. Any other boat was doomed to fail. At that point he'd sailed from the US to New Zealand, and was slipping the boat for major work.

[SecondBase]

Originally Posted by smj

This guy has extensive experience with both mono and multi.
http://www.yachtingworld.com/skip-no...wins-out-70549

I'll read this - nothing else to do since we're more than 40 miles up river from Ft Myers and tucked in tight.

I'd really enjoy an article from an expert like Skip to go right through John Vigor's checklist, plus his additional considerations, and get Skip's professional point of view. Might get us away from conjecture.

For example if he can refute the older, valid "how your rudder is attached matters" points that John made I'd enjoy learning something.

[zeehag]

i have a question for all of you argumentative folks
ok here goes
is ok. gotta have a build up.. drum roll please.....
if a 47 durbeck heavy and i mean heavy cruising ketch can fly 62 miles to be found in a tree 62 miles from biloxi mississippi in katrina, how far can a flipping catamaran fly???

my baby black cat can flip from 3 ft altitude when dropped. we practice standing back flips with treats there is also a tuck n roll technique cats have that is intriguing to watch. i donot know how they do it.

[model 10]

[QUOTE=rabbi;2473366]canvas storm skirts...
I have never been in anything close to Irma but certainly no canvas something would survive winds that are capable of flipping a cat. Cats don't flip in storm winds, only in total desasters that not even houses survive.


Well airplanes can go 400mph covered in canvas. Seems like somebody could think of something for a boat. You can take off in almost a million pound airplane at 185kt. Maybe some sort of storm sail that pushes the bow down?

[SecondBase]

Originally Posted by smj

This guy has extensive experience with both mono and multi.
http://www.yachtingworld.com/skip-no...wins-out-70549

Skip makes a great point - for a family charter, in season, catamaran is the way to go. This particular article, not Skip, is light in seaworthiness analysis. So this is a call for a talented author like Mr. Novak to square the catamaran trend vs John Vigor's gritty checklist. One point might be it is harder to breach 2 hulls than one.

I'd enjoy reading that article !

[smj]

Originally Posted by SecondBase

I'll read this - nothing else to do since we're more than 40 miles up river from Ft Myers and tucked in tight.

I'd really enjoy an article from an expert like Skip to go right through John Vigor's checklist, plus his additional considerations, and get Skip's professional point of view. Might get us away from conjecture.

For example if he can refute the older, valid "how your rudder is attached matters" points that John made I'd enjoy learning something.

If your anchored at the lollipop why don't you travel 2000 ft to the SW and check on my boat? How is it out there?