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Old 13-05-2015, 18:20   #541
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Re: The criteria of "blue"

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Originally Posted by Steady Hand View Post
The trick is to not "drop" down the wave, but instead to ride up the wave front and let it pass beneath the boat.
You've done a lot of research and I think your findings tend to confirm Monsratt's methods (actively steering towing warps or whatever) may be preferable to Pardey's (lying ahull with parachute anchor), at least in some instances. That may be too simplistic and my limited experience tends to confirm that view also, but there is huge disagreement here. As you say, it's up to the skipper to fully inform himself - a whole other subject for another thread.

My only point is - that rogue wave appears suddenly out of the blackness, and from a completely different direction! You are overwhelmed before any directional change can be effected.

Strong, stable boats survive, others might not. (Geese I need to shut up let someone else post here)
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Old 13-05-2015, 18:23   #542
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Re: The criteria of "blue"

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"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.
Some of the old school designers I have been reading lately think that deck houses are big contributors to the risk of turning turtle.

Basically that which is designed to provide high AVS or give high AVS as a by product is the very same thing that would cause you to reach the limits of that AVS and beyond. The curl of a breaking wave likes the extra leverage provided by a deck houses as tons of water is dumped on to what effectively becomes a protrusion when a boat is heel at 90.

I read one document some time back by a designer who said they should not be allowed on anything less than 35 foot because a 12 foot wave which is the "average" height of all waves is enough to put less than 35 on its back and deck house helps it happen.

It maybe though that designers simply can't make full monty deck houses strong enough unless they uses exotic materials or heavy ones and the boat becomes a bit wobbly in normal use undermining the righting moment so most prefer not to make them.

Who's right - ISO or the designer? Have no idea. Maybe both are right and both are wrong.

I do know though that wave height distribution and probability calculation is a very clever science and I would imagine ISO will be tuned into this a little bit more than your average boat designer. So maybe ISO has the bigger picture and in a world of averages and probabilities has determined there are more pro's than cons to having a deck house than not.
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Old 13-05-2015, 18:24   #543
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Re: The criteria of "blue"

So we have older steel boats. Designers not active or dead.

How would one calculate AVS etc. short of spending a ton of money?
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Old 13-05-2015, 18:46   #544
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Re: The criteria of "blue"

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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.


That video is cool as mustard. Now we understand why it hurts when we dive off the top platform. Ouch!

The bubble is cool as well. You think it works though when its raining? Not sure you would see much.
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Old 13-05-2015, 18:52   #545
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Re: The criteria of "blue"

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So we have older steel boats. Designers not active or dead. How would one calculate AVS etc. short of spending a ton of money
Fair question. What I'm doing (because most older yachts that I can afford don't have AVS data available) is looking at the general characteristics that cause a particular design or type of yacht to have a high or low value. Grossly oversimplifying for clarity here:
- Pilothouse yachts will tend to have very high AVS (but there is a downside!)
- Wide beam yachts tend to have low AVS (high initial (form) stability tends to make them equally stable inverted - not so good)
- Narrow beam, traditional designs (relying on ballast for stability, rather than wide beam) tend to have high AVS.
- Flush deck will have lower AVS than a raised cabin trunk (steel boats should have no worries over cabin trunk being dislodged or damaged)
- High ballast ratio, or deep keel, (or both!) will have higher AVS (that's how deep and shallow keel configurations of the same vessel can have the same AVS - the designer simply increases the amount of ballast)
- heavy (steel) yachts may tend to have lower ballast ratios (not always though - don't take my word on this), so lower AVS, in some cases (but added inertia is always good in a storm - high inertia requires more wave energy to cause the knockdown).

AVS is only a guide at best, even when calculated to great accuracy for a specific design (add that in-mast furler and the AVS reduces 20 degrees!) so exact figure is less important than identifying general characteristics that lead to greater ultimate stability, IMO.
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Old 13-05-2015, 19:03   #546
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Re: The criteria of "blue"

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So we have older steel boats. Designers not active or dead.

How would one calculate AVS etc. short of spending a ton of money?


I am guessing the proving ground is real life. Seal the boat and turn it over.

Good question I will try to find out.. However I do know that some mast suppliers will not supply rigs unless they have these numbers given.
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Old 13-05-2015, 19:17   #547
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Re: The criteria of "blue"

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... your findings tend to confirm Monsratt's methods (actively steering towing warps or whatever)...
Monsaratt???!!! Sorry, I meant Bernard Moitessier of course
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Old 13-05-2015, 19:19   #548
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Re: The criteria of "blue"

I've just dug out the 'Inclining Experiment Report and Stability Assessment' for my boat...OK a sistership... all 30 pages of it.
This was done in 1991 as she was in service as a sail training yacht and she had to comply with the UK 1990 Safety of Sail Training Ships Code of Practice.

Inclining experiment carried out with the ship in almost all respects ready for sea... full fuel and FW, roller furler etc etc... only vittles and crew absent.

Found to comply with Cat 2... near continental ...under those regs ie AVS greater than 121* and less than 131*.... however the fitting of a Firdell Blipper to the mast would take her into Cats 1 and 0.

A heeling experiment isn't too hard... if you know what you are doing....

I wouldn't stress toooo much about needing a huge AVS...lots more to worry about...like storm jibs.

I went for a wander around the marina yesterday evening.... plenty of 'blue water' boats to be seen... only found one that could set a hanked on storm jib........

Them as had inner forestays invariably had roller furling staysails on 'em.
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Old 13-05-2015, 19:34   #549
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Re: The criteria of "blue"

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A heeling experiment isn't too hard... if you know what you are doing....
... but the calculations required of that inclining experiment, also requiring the full lines plan, are way beyond the ability of mere mortals. Inclining only gives us the CoG - we still need CoB and all those heeled waterlines (never parallel to upright WL) to arrive at AVS.

But I agree - don't focus too much on AVS - there are much greater concerns.
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Old 13-05-2015, 19:40   #550
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Re: The criteria of "blue"

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Some of the old school designers I have been reading lately think that deck houses are big contributors to the risk of turning turtle.


I read one document some time back by a designer who said they should not be allowed on anything less than 35 foot because a 12 foot wave which is the "average" height of all waves is enough to put less than 35 on its back and deck house helps it happen.

Not be allowed? By whom? Some autonomous body crafting regulations? There is not an agreement as to what "blue" actually is never mind what is the best boat to transit it. That, of course, would not stop a government from feeling it necessary to regulate "it". Is that a good thing?

Be careful what you wish for.
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Old 13-05-2015, 20:05   #551
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Re: The criteria of "blue"

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Originally Posted by El Pinguino View Post
I've just dug out the 'Inclining Experiment Report and Stability Assessment' for my boat...OK a sistership... all 30 pages of it.
This was done in 1991 as she was in service as a sail training yacht and she had to comply with the UK 1990 Safety of Sail Training Ships Code of Practice.

Inclining experiment carried out with the ship in almost all respects ready for sea... full fuel and FW, roller furler etc etc... only vittles and crew absent.

Found to comply with Cat 2... near continental ...under those regs ie AVS greater than 121* and less than 131*.... however the fitting of a Firdell Blipper to the mast would take her into Cats 1 and 0.

A heeling experiment isn't too hard... if you know what you are doing....

I wouldn't stress toooo much about needing a huge AVS...lots more to worry about...like storm jibs.

I went for a wander around the marina yesterday evening.... plenty of 'blue water' boats to be seen... only found one that could set a hanked on storm jib........

Them as had inner forestays invariably had roller furling staysails on 'em.


I think you are right, there are many more things one could worry about (or prepare on any yacht) that will likely have a greater likelihood of mattering WHEN (or IF) the boat capsizes, and I think many yacht owners fail to prepare for those things. At least that is how I see it based on reading so many reports of boats lost or abandoned in recent years.

I have more thoughts on this, and I usually don't like posting just a simple or brief statement like the one above, but I think more would need to be in a different thread/topic.
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Old 13-05-2015, 20:52   #552
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Re: The criteria of "blue"

Bubble Hatch (in rain)?

I have wanted one of these since I saw Moitessier use one on his boat Joshua.

Seemed like a great idea many years ago and I always thought "that looks great for bad weather."

But, I don't think it has to be only practical for use in a storm. I have been below deck during heavy rain and wanted to look at the sails and not wanted to go up on deck or even open the companionway hatch to see around, because opening the sliding hatch cover would have let a LOT of water into the boat. It would be nice to simply stick one's head up into the dome for a look around.

Rain on the dome? I think some regular coats of "Rain-X" (a commonly found rain dispersing fluid/coating in the USA) would make it easier to see through. It works very well on my vehicle windscreen. Water/rain beads up and blows right off. Salt spray may be different, TBD (to be determined).

Anyway, you started the thread/discussion about "Blue," and this particular feature/gear/hatch is something I always thought of as "blue water" oriented and practical.
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Old 14-05-2015, 03:41   #553
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Re: The criteria of "blue"

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Anyway, you started the thread/discussion about "Blue," and this particular feature/gear/hatch is something I always thought of as "blue water" oriented and practical.
This boat is for sale at the moment:


Greyhound

Has two of those bubbles. And certainly "blue water". Was build for the OSTAR... I almost bought this boat when it was for sale in the 90ies, maybe I should now.
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Old 14-05-2015, 04:43   #554
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Re: The criteria of "blue"

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Bubble Hatch (in rain)?

I have wanted one of these since I saw Moitessier use one on his boat Joshua.

Seemed like a great idea many years ago and I always thought "that looks great for bad weather."

But, I don't think it has to be only practical for use in a storm. I have been below deck during heavy rain and wanted to look at the sails and not wanted to go up on deck or even open the companionway hatch to see around, because opening the sliding hatch cover would have let a LOT of water into the boat. It would be nice to simply stick one's head up into the dome for a look around.

Rain on the dome? I think some regular coats of "Rain-X" (a commonly found rain dispersing fluid/coating in the USA) would make it easier to see through. It works very well on my vehicle windscreen. Water/rain beads up and blows right off. Salt spray may be different, TBD (to be determined).

Anyway, you started the thread/discussion about "Blue," and this particular feature/gear/hatch is something I always thought of as "blue water" oriented and practical.
I have seen them offset to port or starboard above the nav station to give an external view in boats with minimal saloon height. I have wondered about them. I just wondered how they are defended against bad weather in that position so that visibility is not inhibited. If they were caped somehow at the top in a minimalist way you could include a manual wiper mechanism. They are interesting and definitely get round the problem of having to raise the saloon to see out whilst being buttoned up.
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Old 14-05-2015, 04:44   #555
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Re: The criteria of "blue"

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This boat is for sale at the moment:


Greyhound

Has two of those bubbles. And certainly "blue water". Was build for the OSTAR... I almost bought this boat when it was for sale in the 90ies, maybe I should now.
Looks as tough as nails.
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