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Old 13-05-2015, 06:04   #526
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pirate Re: The criteria of "blue"

Quote:
Originally Posted by paulanthony View Post
Some one on another thread called Jedi mentioned water tight compartments with NO through holes in the center compartment.

Sounds very logical but never thought of it before.

Is this a iso standard for cat A: Getting into the realms of unsinkable thought.
No its not..
Jedi tends to talk sense..
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Old 13-05-2015, 06:18   #527
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Re: The criteria of "blue"

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Originally Posted by paulanthony View Post
That's kind of awesome. I read also that side doors simply will not qualify for an A rating even if the the craft is a able to maintain water tight integrity in a big knock down. It is simply not tested for and is down graded to B by default.
Hi. Friendly question and comments follow to clarify and to add to the discussion.

Do you have a source (citation) for the statement about the "simply not tested and is down graded to B by default?" In other words, where does that come from or who said it? I would like to see it if possible.
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The Nauticat line of boats includes SOME boats (their "Traditional Motor Sailor" styled boats such as the MS44) that have the side door/hatches that are sliding. That type of large "door style" hatch on the side of the pilot house cabin is considered the weak point (being closer to the water in a knockdown, large opening etc.) for possible water ingress and down-flooding in a knockdown or capsize.

But, that same type of sliding door is also found on many "blue water" smaller commercial fishing vessels (but likely made in steel). On SOME of the Traditional Motor Sailor styled boats the hatch is easy to see as it was made in a contrasting "wood" finish that stands out visually from the rest of the cabin/pilot house. The Nauticat 38 Traditional Motor Sailor is an example.

Some other of the Nauticat models (also considered "pilot house" designs) have their companionway hatch in the centerline of the boat (as seen in typical sailboats) with the hatch opening to the cockpit rather than the side deck and typical hatch boards and sliding hatch (typical again).

So, it is important to know specifically WHICH Nauticat model one is speaking of when discussing the hatches and AVS etc.

I will post a few photos to illustrate these features. Notice that most of the photos I am posting show the sliding side "door style" hatch shown on SOME of the Nauticat models. I will also post a couple of photos showing the "centerline typical" hatch that is on SOME of the Nauticat models.
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Old 13-05-2015, 07:01   #528
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Re: The criteria of "blue"

Quote:
Originally Posted by paulanthony View Post
Some one on another thread called Jedi mentioned water tight compartments with NO through holes in the center compartment. ..... Is this a ISO standard for cat A? Getting into the realms of unsinkable ...
Paul, you yourself quoted from ISO12217-2 (about 355 pages back on this thread):
"...boats may also be assigned to category A or B provided that certain limitations are fulfilled. Simplyfying here only the more relevant ones:
a) AVS ≥ 90º for category A, ...
b) when the swamped or inverted boat is totally inmersed, buoyancy is sufficient to support the mass of the loaded boat by a margin
c) watertight compartments used to provide buoyancy shall be constructed to watertightness degree 1 in accordance with ISO 11812 and hatches and doors satisfy watertightness degree 2 of ISO 12216 ...."


I took this to mean that Cat A allows a reduced AVS of 90º if a monohull yacht retains positive buoyancy after flooding. I believe many smaller French-built keelboats were designed this way, i.e. they are 'unsinkable'.
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Old 13-05-2015, 07:24   #529
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Re: The criteria of "blue"

Ok so here is a question. How do you find out a boats Avs?


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Old 13-05-2015, 07:42   #530
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Re: The criteria of "blue"

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Originally Posted by brookiesailor View Post
...How do you find out a boats Avs?
Google "RYA Stability List" and you'll find a database of around 400+ yachts in alphabetical order. I'm afraid it's a most unwieldy spreadsheet: AVS comes into a column that is way across the pages from the boat's name - it's a nightmare to try to read. Has anyone found a better source?

I've managed to 'unfreeze' the spreadsheet and get rid of 50% or more of the useless information - makes it much easier to read and you can then select the size of boats you are interested in and leave out the rest.

Individual builders also provide stability data on their boats in some cases - I think all European builders are required to and the better builders should have GZ curves available on their websites.
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Old 13-05-2015, 08:08   #531
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Re: The criteria of "blue"

Quote:
Originally Posted by Steady Hand View Post
Hi. Friendly question and comments follow to clarify and to add to the discussion.

Do you have a source (citation) for the statement about the "simply not tested and is down graded to B by default?" In other words, where does that come from or who said it? I would like to see it if possible.
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This is not the quote I was trying to find to pass over to you. I have seen a more detailed explanation some place.

"Nauticat 441 is the CE B-category boat and we have a dream to cross the oceans one day. Nauticat Yachts Ltd managing director Kaj Gustafsson told that "CE B-classification is due to EU certification requirements that count side doors as the downflood opening. Even thou the 441's aluminium frame doors are watertight enough EU officials speculate that a crew member may forget the door open and the doorstep will be thus counted as a downflood opening. The whole yacht is however designed and built fully according to the CE category A requirements. In other countries like Japan, Nauticat 441 is approved as an ocean capable yacht.""


From this link https://www.suwena.net/en/taxonomy/term/11

I will try to find the others source as I go.. Keeps cropping up so I will find it. Hope this helps in the mean time.

P.S I am guessing the wordage sounds like the yard owner is implying all and any of their boats with sliding doors falls foul of the cat rating.

Have you got a Nauticat Steady Hand? - I do like them.
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Old 13-05-2015, 08:16   #532
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Re: The criteria of "blue"

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Originally Posted by NevisDog View Post
Paul, you yourself quoted from ISO12217-2 (about 355 pages back on this thread):
"...boats may also be assigned to category A or B provided that certain limitations are fulfilled. Simplyfying here only the more relevant ones:
a) AVS ≥ 90º for category A, ...
b) when the swamped or inverted boat is totally inmersed, buoyancy is sufficient to support the mass of the loaded boat by a margin
c) watertight compartments used to provide buoyancy shall be constructed to watertightness degree 1 in accordance with ISO 11812 and hatches and doors satisfy watertightness degree 2 of ISO 12216 ...."


I took this to mean that Cat A allows a reduced AVS of 90º if a monohull yacht retains positive buoyancy after flooding. I believe many smaller French-built keelboats were designed this way, i.e. they are 'unsinkable'.
I should read my own words sometimes.. ISO 12216 got past my net.

Well spotted!
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Old 13-05-2015, 08:28   #533
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Re: The criteria of "blue"

Quote:
Originally Posted by paulanthony View Post
This is not the quote I was trying to find to pass over to you. I have seen a more detailed explanation some place.

"Nauticat 441 is the CE B-category boat and we have a dream to cross the oceans one day. Nauticat Yachts Ltd managing director Kaj Gustafsson told that "CE B-classification is due to EU certification requirements that count side doors as the downflood opening. Even thou the 441's aluminium frame doors are watertight enough EU officials speculate that a crew member may forget the door open and the doorstep will be thus counted as a downflood opening. The whole yacht is however designed and built fully according to the CE category A requirements. In other countries like Japan, Nauticat 441 is approved as an ocean capable yacht.""


From this link https://www.suwena.net/en/taxonomy/term/11

I will try to find the others source as I go.. Keeps cropping up so I will find it. Hope this helps in the mean time.

P.S I am guessing the wordage sounds like the yard owner is implying all and any of their boats with sliding doors falls foul of the cat rating.
Thanks for posting the quote.

In a storm or heavy seas, I would keep the hatch shut on any boat! Even if it was a brief squall I would shut the hatches to prevent rain from soaking my interior. Which is why I like Dorades so much.

But, of course there is the unexpected, such as high wind, clear day, spinnaker broaches, white squall knockdowns, supertanker bow waves, and the ever possible, dreaded "rogue wave" too.

My solution would be to simply have a boat rule to treat that side hatch as if it were a refrigerator door when sailing: open it to get in and shut it otherwise.
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Old 13-05-2015, 08:48   #534
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Re: The criteria of "blue"

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Originally Posted by Steady Hand View Post
Thanks for posting the quote.

In a storm or heavy seas, I would keep the hatch shut on any boat! Even if it was a brief squall I would shut the hatches to prevent rain from soaking my interior. Which is why I like Dorades so much.

But, of course there is the unexpected, such as high wind, clear day, spinnaker broaches, white squall knockdowns, supertanker bow waves, and the ever possible, dreaded "rogue wave" too.

My solution would be to simply have a boat rule to treat that side hatch as if it were a refrigerator door when sailing: open it to get in and shut it otherwise.
Fishing vessels get built under Lloyds or ABS classification or a working vessel variant of the ISO standard. I also wondered how a fishing boat can be A rated but it is to do with commercial ratings and not a pleasure craft ones.. (I think)
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Old 13-05-2015, 09:10   #535
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Re: The criteria of "blue"

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Originally Posted by paulanthony View Post
Fishing vessels get built under Lloyds or ABS classification or a working vessel variant of the ISO standard. I also wondered how a fishing boat can be A rated but it is to do with commercial ratings and not a pleasure craft ones.. (I think)
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Old 13-05-2015, 16:06   #536
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Re: The criteria of "blue"

When a boat is trimmed where can those cues be taken from. Passive auto pilot?
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Old 13-05-2015, 16:33   #537
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Re: The criteria of "blue"

"ISO stability curves do account for a raised cabinhouse, but not all designers believe this is a good thing... The ISO formulas (for calculating AVS)... may award high stability ratings to... deck-saloon boats... that may be vulnerable in extreme conditions." - Douane.

Since this thread is all about 'blue', extreme conditions should be an important consideration here. Remember that a 'knockdown' or a 'rollover' is not caused by wind, but by waves. (The most dangerous time, deep offshore, is when the wind begins to abate, allowing distant waves to merge and build to far more dangerous levels as they travel towards you - that's when you must cease to lie ahull and get the vessel underway again for a small yacht to survive.)

Anyone who has experienced a knockdown due to wave action will tell you it is like hitting concrete as the boat drops 20m or so from the breaking crest to the trough below. In these conditions, those decorative wooden sliders on the Nauticats would shatter like matchwood. Was it Tzu Hang or some other sturdily built vessel, where the entire cabin trunk shifted sideways in a knockdown, leaving a gaping hole in the deck where the trunk once was? (Okay Tzu Hang was pitchpoled, so it may have been some other yacht.) Damage always occurs on the lee side - the downflooding side.
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Old 13-05-2015, 16:56   #538
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Re: The criteria of "blue"

Years ago while racing, the idea of using a 24 foot boat for the Single Handed Transpac had come up but we found that by adding all the weight of food and water changed the dynamics of the boat and slowed it considerable which meant adding more food and water for the extended time, we were talking a fair percentage of weight5 gain.. So I bring up the issues at hand with all the numbers.. The numbers are such as rated for the boat based on weight and displacement .. When you take a couple, all their goodies, the stores, fuel, water and everything else for a cruising life,
Are you changing the numbers by adding the weight..
On our boat, dry weight is around 24k, but we probably add another 4k in weight for cruising. Thats a pretty good percentage addition.
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Old 13-05-2015, 17:55   #539
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Re: The criteria of "blue"

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Originally Posted by NevisDog View Post
"ISO stability curves do account for a raised cabinhouse, but not all designers believe this is a good thing... The ISO formulas (for calculating AVS)... may award high stability ratings to... deck-saloon boats... that may be vulnerable in extreme conditions." - Douane.

Since this thread is all about 'blue', extreme conditions should be an important consideration here. Remember that a 'knockdown' or a 'rollover' is not caused by wind, but by waves. (The most dangerous time, deep offshore, is when the wind begins to abate, allowing distant waves to merge and build to far more dangerous levels as they travel towards you - that's when you must cease to lie ahull and get the vessel underway again for a small yacht to survive.)

Anyone who has experienced a knockdown due to wave action will tell you it is like hitting concrete as the boat drops 20m or so from the breaking crest to the trough below. In these conditions, those decorative wooden sliders on the Nauticats would shatter like matchwood. Was it Tzu Hang or some other sturdily built vessel, where the entire cabin trunk shifted sideways in a knockdown, leaving a gaping hole in the deck where the trunk once was? (Okay Tzu Hang was pitchpoled, so it may have been some other yacht.) Damage always occurs on the lee side - the downflooding side.
I believe I understand your POV as I have read things like that years ago too.

Who doesn't love a good "Storm at Sea" story?

But, I have a different POV today, after reading more things and learning more about a different approach to "storm survival" that is highly recommended by very accomplished "blue water" sailors.

For one thing, IF you are dropping 20m down the face of a wave, there is probably little that any crew can do to survive with a crew alive inside.

The trick is to not "drop" down the wave, but instead to ride up the wave front and let it pass beneath the boat.


How can this be possible?

I read the very interesting tests done by Don Jordan (Jordan Series Drogue inventor) and learned something about how the wave action would be if a boat is allowed to slowly move up the wave and to NOT go down the wave front at high speed or yawing to a broach in the trough.

A key aspect of this approach is to let the more buoyant back end of the boat be approached by the wave, with the JSD (Jordan Series Drogue) streaming from the stern with the stern to the oncoming waves.

This is "counter intuitive" and very different (the opposite, in fact) to a commonly recommended and traditional approach that had "a very big parachute sea anchor off the bow, with the boat's bow to oncoming waves."

The testing by USCG confirmed how the boat acts when in breaking waves (off Oregon) and with parachute drogues, Jordan Series Drogues, and other devices.

Anyway, that is how I see it. I have more supporting statements from other very accomplished/respected sailors in my notes, but that is probably best left for another thread on that topic or on "seamanship" issues in the future.

In Sum: My POV is that the decision of what to do in a storm (methods, gear, tactics) a captain makes for his/her boat is their decision. There are differences of opinion on what is "best practice." Based on what I have read from numerous respected sailors and from actual testing conducted by the USCG where I can see the actual results (in documentation), I feel I have a good sense of what I will do in a survival storm situation.
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But back to the issue of big hatches and "wood trim" (the somewhat decorative upper wood pieces are called "eyebrows" above the rollers on a sliding hatch) I will add a few more comments:

1. I think a properly managed/sailed Nauticat (remember there are several models and very different designs, hulls, styles of Nauticats) could be as safe as just about any boat out on the open ocean if one practices good seamanship (batten the hatches, avoid broaching, use a JSD, etc.).

2. Many contemporary yachts (monos and cats) have VERY large pilot house or cabin windows (portlights) and cats even have very large sliding glass doors etc. So, large portlights on "pilot houses" or "cabins" can certainly be a risk, but it is one that many or most sailors seem willing to take in order to have the "deck saloon or cat" views. I will post a photo showing the kind of hatch I would prefer to have on my companionway if I were in a survival storm in a mono. I don't think they make one big enough for a cat.

3. I happened to see a video today on Facebook that shows a large quantity of water dumped from a huge bucket (earth moving machine) on top of a station wagon automobile. The car was crushed by the tons of water coming down on it. So, I respect the damage the weight of water (a breaking sea) that could come down on a boat and the damage it can do to any boat.

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Old 13-05-2015, 17:56   #540
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Re: The criteria of "blue"

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Originally Posted by FastCruiser View Post
...The numbers are such as rated for the boat based on weight and displacement .. When you take a couple, all their goodies, the stores, fuel, water and everything else for a cruising life, are you changing the numbers by adding the weight..
"...the dislacement values used in calculating stability curves are normally lightship, ... even worse, much of this extra weight - in the form of roller-furling, radomes and other heavy gear - will be well above the waterline... installing an in-mast furling system may reduce your boat's AVS by as much as 20 degrees. ... you should assume a loaded cruising boat will have an AVS at least 10 degrees lower than that indicated on a stability curve..." - Douane (again - I keep his book handy!). He goes on to warn about other 'real world' effects: downflooding, cockpit shipping water...

"Lies, damned lies, and statistics" - Winston Churchill.
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