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Old 04-05-2013, 19:40   #271
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Re: Storm Sailing Advice

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Originally Posted by CaptForce View Post
It does help to have all of us speaking the same language. From the most basic definitions that I have looked at, a storm is generally accepted to have winds at a minimum of 55mph for a minimum duration of 12 hours. We might best consider the term squall for those events of the same minimum winds that are normally coastal and for a far shorter duration. This doesn't mean that a squall may not last for 5 hours with winds well over 55mph, but still; these events are usually a result of the temperature dynamics differening between the land that heats and cools faster than the adjacent water. Storms, unlike the squalls, would be associated with large low pressure systems with a vortex or cyclonic movement streching over 100 miles or much more. We might communicate better if we were to use some operational definition to identify these very different weather patterns. Both can be severe and overwhelming, but they do have different characteristics.
I think we should all agree… defining the weather terms and distances from safe refuge, will help us to better qualify the Challenges and suggested Solutions.

STORM:…. As defined by Beaufort scale….
(For me forecast wave heights and wave period dictates the level of danger)

OFFSHORE:….. Simply means you are unable to seek Coastal refuge before the STORM has passed

COASTAL:…. Option to seek shelter, tempered by dangers of a Lee Shore…
ie../Shoaling and Confused Seas…/Tidal and river affects… plus /possibility of Orographic and Anabatic effects of Coastal Topography, creating hurricane force wind bullets.

Assuming you are caught fully in the path of a large STORM system:

OFFSHORE Tactics are much simpler to decide upon as generally the wave periods and directions are predictable as the STORM passes over your position.
If she is handling and recovering from the breaking seas and crest top windage well, then relieving stress on boat by crabbing out of danger zone under a storm sail is usually the first stage of survival.

However, I am like Boatman…. If it gets too hairy, but I trust the boat, I will position her to be self-tending and get everyone safely down below.

COASTAL Tactics are far more challenging and dynamic and I think impossible to define except deciding if your refuge port is accessible in those conditions.
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Old 05-05-2013, 04:55   #272
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Re: Storm Sailing Advice

^^

There are three challenges with using the met definitions to discuss 'storm tactics':

#1 is that waves are the primary driver of storm tactics, while the met definitions are mostly about the wind. You can have flat (but smoking) water in 60kts while you can have severely dangerous breaking waves in 40kts. So, my conclusion is that if you want a 'standard' set of definitions they have to be about the wave size and shape, which unfortunately 'storm' and 'gale' are not.

#2 The waves are relative to the boat and crew. For instance, it's generally agreed that lying a hull is no problem and is 'safe' (but uncomfortable) until the waves (both) get to be the height of the beam and start breaking (breaking, not just white capping or cresting, which gets into another set of wave definitions). Obviously that point is going to be earlier for a 26' boat than for an 80' boat. And an experienced crew is going to be much more comfortable and safer using the active running technique in bigger conditions than an inexperienced crew. So, it's all relative to the boat and crew.

#3 The met definitions use 'sustained winds', and most cruisers read the gusts off their wind instruments as 'the wind' and so think they are in more wind than the met definitions suggest. Further there is also a strong human psychological tendency to add a bit to the gusts . . . if you see 38kts, in your mind it often becomes +40kts, and then in retelling later it becomes 45kts. And finally some of the most noted 'experts' (see at least two out of 4 of the authors we discussed way up the thread) don't even have wind instruments. . . . their judgment of wind speeds under 35kts is probably pretty accurate, but because it's so rare I doubt their judgment of wind over 50kts is very accurate. I see a lot of photos where people claim more than 60kts, and anyone who's actually been in 60kts can see immediately it's not . . . there is a 'phase change' and the water starts to smoke around then. So, even if the met wind speeds were useful (which as I suggest in 1 & 2 above I don't think they are), 'sailor wind speeds' are often quite different than the official met winds.

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So IMHO, the official met definitions are pretty much useless in trying to discuss when to use which technique. You need to start with wave size and shape. But then you have to also add in a whole set of qualitative 'feel' factors.
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Old 05-05-2013, 07:26   #273
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Re: Storm Sailing Advice

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The met definitions use 'sustained winds', and most cruisers read the gusts off their wind instruments as 'the wind' and so think they are in more wind than the met definitions suggest. Further there is also a strong human psychological tendency to add a bit to the gusts . . . if you see 38kts, in your mind it often becomes +40kts, and then in retelling later it becomes 45kts.
The average is the lowest number you see on your wind speed indicator! Mind you in the Cape Palliser storm we had the windspeed pegging the indicator at it's maximum of sixty knots for at least an hour before it finally failed. The sea was much like your picture Evans, except with 20-25 foot breaking waves on top of it!

This is an interesting read on the metservices recorded windspeeds, compared to the yachts for the 98 Syd/Hob.

I also strongly suspect they windspeed indicators overread in a seaway. I have been at sea with the thing jumping to 55 knots but it's only a force 8 by my reckoning having served as a met observer for 7 years on Voluntary Observing Ships.

If you look at all the bigger storms that have hit fleets the common thread is that most of the yachts that got into trouble pretty much were handling the conditions OK until a rogue wave from 'nowhere' got them. I think these are the real problem, and it is more a matter of luck than specific tactics that most of the fleet in similar boats nearby get through OK.

The three times I have been knocked down it was always in conditions that were absolutely fine, with the boat handling the conditions with ease, All three waves came out of nowhere and where at least twice the height of the biggest waves I had seen up till then. They all had large breaking crests that where roaring, and where at least 20 degrees off the normal wave train direction. All the knockdowns where past 90 degrees. One time I was hand steering, the other two the windvane was. All times the wind was well aft of the beam. They where all on boats under 35 feet well offshore.

A rogue wave in a real storm will (I think) almost certainly capsize most cruising yachts no matter what tactics are in use (except maybe a parachute or series drogue, and even then serous structural damage is possible). I saw a storm rogue wave once from the bridge of a container ship. It was a trough about 70+ foot deep with what seemed like vertical sides, defying gravity. The thing I remember was that it wasn't breaking as such, but the water seemed to be flowing uphill somehow. It just missed us thankfully, and we continued slow steaming into the force 10 westerly south of the Aussie bight.

We tend to look at events like the sydney/hobart and say those people that capsized used the wrong tactics or had a poor choice of the boat, because look at all the boats that survived ok. I think it's more likely they were just in the wrong place at the wrong time, had they been 100 meters away they would have been just fine.
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Old 05-05-2013, 07:52   #274
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Re: Storm Sailing Advice

^^

Wave size distribution is a critical piece of all this (and something I should add to my article).


The distribution of waves sizes is quite predictable (Rayleigh distribution for anyone interested). Here's a graph I used in the Low Speed Chase incident investigation.

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They had 14' significant wave heights (the commonly use met service wave height). That means that 1 in 100 were 21' and 1 in 1000 were 26', and the mean wave is only 8' (you can see all this in wave reporting buoy data). With a 13 sec wave period you are going to get one of those 1 in 1000 waves about every 3 and 1/5 hours. So every 3 hours you are getting a wave that is 8x bigger than the mean and almost 2x the significant height. Low Speed Chase were comfortable in the 14' waves, but were rolled and 5 people died by that 1 in 1000 26' wave.

When you are setting your boat up and deciding if it 'feels right' you need to realize that you ARE going to occasionally get much bigger waves and factor that in. Those waves are not really 'luck' . . . they are going to happen at a relatively predictable frequency. The luck comes in to play in where and how they hit you and if and where exactly they break.

But the message is you clearly need to anticipate these bigger waves and factor them into your decision making.

I have never quite figured out what to say about 'luck' in all this. It obviously does play a role. There are very occasional (even less than 1 in 1000) waves that no boat using any tactic will survive (like the wave that hit the QE2 and broke bridge windows). But I think proper preparation and anticipation and 'feel' make the luck component much smaller than many people would think.
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Old 05-05-2013, 08:27   #275
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pirate Re: Storm Sailing Advice

I got nuttin to add to this more or less great discussion except the wish that all the newby circumnavigators each year would be asked to read about heavy weather and spouses would be tied down and force fed
video clips of big waves. The EPIRB market would fold, and the SAR crews wouldn't be out risking their lives for nothing.
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Old 05-05-2013, 09:13   #276
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Re: Storm Sailing Advice

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Right raku but usually we know so we are not days coastal sailing in major weather systems. My experience is that I can miss most or all big stuff while coastal sailing. Much more likely that I get caught in a fast moving cold front that kicks me for 20 minutes dangerous but also manageable. My strategy for coastal storm management us very different to offshore preparation.

I am very glad you have had that experience. However, I have seen these unexpected and unpredictable storms. This means that one day it could, conceivably, happen while sailing.

I think it would be the height of folly to not pay attention when more experienced sailors talk about storm strategies. I would not get caught in a fast moving storm front, with my current style of sailing because I pay attention to the weather.

It's a choice. We still had seven or eight boats sail across Tampa Bay yeserday to come south. We had a great time visiting, but they sailed down in small craft advisories and went back the same way.

It was avoidable. They all made an educated choice and they were all fine.

That's not what we've been talking about here.

I've seen it and now I have heard *from the mouth of a local meterologist with the NWS* that it can happen here, and that's good enough for me.
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Old 05-05-2013, 10:35   #277
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I have seen these unexpected and unpredictable storms. ... I've seen it and now I have heard *from the mouth of a local meterologist with the NWS* that it can happen here, and that's good enough for me.
Bwaaaaahahahahah! I heard somewheres that damned Tampa Bay was worse than the Southern Ocean.
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Old 05-05-2013, 15:46   #278
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Re: Storm Sailing Advice

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Originally Posted by estarzinger View Post
The distribution of waves sizes is quite predictable (Rayleigh distribution for anyone interested). Here's a graph I used in the Low Speed Chase incident investigation.

Attachment 60404

They had 14' significant wave heights (the commonly use met service wave height). That means that 1 in 100 were 21' and 1 in 1000 were 26', and the mean wave is only 8' (you can see all this in wave reporting buoy data). With a 13 sec wave period you are going to get one of those 1 in 1000 waves about every 3 and 1/5 hours. So every 3 hours you are getting a wave that is 8x bigger than the mean and almost 2x the significant height.
Until recently, I believed that wave height follows this Rayleigh distribution, giving a fixed ratio between "significant wave height" (the average of the upper third of waves), "H 1/100" and H 1/1000".

But part of my job is now operating a wave buoy (this model: http://www.datawell.nl/Portals/0/Doc...g4_b-06-06.pdf) for measuring waves during sea trials of ships and I am forced to admit that practice doesn't always agree precisely with the theory: there is some dispersion in results. See for example: CANDHIS - Campagne

Alain
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Old 05-05-2013, 15:55   #279
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Re: Storm Sailing Advice

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There are very occasional (even less than 1 in 1000) waves that no boat using any tactic will survive (like the wave that hit the QE2 and broke bridge windows)
This is where I think the preparation pays off big time. If you have chosen a strong hull, and set it up with the possibility of being rolled or pitchpoled in mind. With things like strong locker catches, strong hatches, a safe place for crew, a the mental attitude to cope with a capsize. You stand pretty good odds that you will survive such a wave, even if your boat is rolled and badly damaged.

Injuries are the biggest threat here along with the mast which will most likely be trying to bash a hole in the boat. The good news being that the chance of another similar wave in the same storm is very remote.

This is not to say your tactics are not important, they are very important to insure the larger of the normal waves do not capsize you. So I guess there is pleanty of room to improve your 'luck' or odds.
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Old 05-05-2013, 16:22   #280
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Re: Storm Sailing Advice

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Bwaaaaahahahahah! I heard somewheres that damned Tampa Bay was worse than the Southern Ocean.

Don't sail on Tampa Bay, but somehow I doubt it...
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Old 05-05-2013, 16:51   #281
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Re: Storm Sailing Advice

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there is some dispersion in results.
Agreed. I believe the latest data suggests the tail of the distribution is actually quite a bit fatter than the Rayleigh distribution suggests. I have not looked at this in a couple years . . . are there any good recent papers on the web about new findings/developments on waves, especially in the tail?

This is the case when almost all models are applied in the real world - the real world is always more complicated and the models never fit perfectly. You can only hope they fit well enough to provide some useful insight, and in this case I think it does. The insights being that there will certainly be a range of waves, with a not insignificant fraction at least twice the significant height, and you should anticipate that.

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If you have chosen a strong hull, and set it up with the possibility of being rolled or pitchpoled in mind. With things like strong locker catches, strong hatches, a safe place for crew, a the mental attitude to cope with a capsize. You stand pretty good odds that you will survive such a wave, even if your boat is rolled and badly damaged.

So I guess there is pleanty of room to improve your 'luck' or odds.
Agree completely. Hawk is not a total tank like some of the Puerto Williams boats (because I wanted better sailing than that), but she is very strong, with the secure closures on all lockers and the strongest possible hatches. we had a friend who was preparing to sail from NZ to the Falkland's (non-stop) in a westsail 32, who asked Eric H what his advice was - he said "do everything you can to keep the water on the outside".
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Old 05-05-2013, 17:16   #282
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Re: Storm Sailing Advice

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Agreed. I believe the latest data suggests the tail of the distribution is actually quite a bit fatter than the Rayleigh distribution suggests. I have not looked at this in a couple years . . . are there any good recent papers on the web about new findings/developments on waves, especially in the tail?

This is the case when almost all models are applied in the real world - the real world is always more complicated and the models never fit perfectly. You can only hope they fit well enough to provide some useful insight, and in this case I think it does. The insights being that there will certainly be a range of waves, with a not insignificant fraction at least twice the significant height, and you should anticipate that.
IME, the average conditions change relatively fast: the main direction and peak period of the wave spectrum keep moving. Then, the sea state doesn't have the time to comply with the Rayleigh distribution, which requires a larger number of waves.

Evans, I agree with you: it is necessary to take into account a 100% probability of meeting approximately 1 wave in 100 being twice the significant height. This is also true when calculating the keel clearance for sailing in shallow areas.

Alain
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Old 05-05-2013, 17:36   #283
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Re: Storm Sailing Advice

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Don't sail on Tampa Bay, but somehow I doubt it...
I'm curently on Anna Maria Island just south of Tampa Bay. Sure was blowing yesterday and today on the Gulf. Was glad I was not out there. Laying down nicely tonight though now I wish I was.
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Old 05-05-2013, 17:37   #284
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Re: Storm Sailing Advice

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Evans, I agree with you: it is necessary to take into account a 100% probability of meeting approximately 1 wave in 100 being twice the significant height. This is also true when calculating the keel clearance for sailing in shallow areas.

Alain
When you think about this, it means that every 15 minutes or so that 2x wave will come along. I guess this means that "merely" being twice the sig height isn't usually a big deal since we've all sailed in biggish seas for much longer than 15 minutes without serious incident. It is the events further out in the distribution that are worrisome.

But as someone pointed out earlier, it is often not the giant wave that does you in, but one that comes from some different direction than the general wave train. I believe that sort of event was what caused our one knockdown at sea... don't really know, for we were both below at the time.

Cheers,

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Old 05-05-2013, 19:25   #285
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Re: Storm Sailing Advice

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^^

There are three challenges with using the met definitions to discuss 'storm tactics':

#1 is that waves are the primary driver of storm tactics,.....

#2 The waves are relative to the boat and crew. .....

#3 The met definitions use 'sustained winds', and most cruisers read the gusts off their wind instruments as 'the wind' and so think they are in more wind than the met definitions suggest. Further there is also a strong human psychological tendency to add a bit to the gusts . . . if you see 38kts, in your mind it often becomes +40kts, and then in retelling later it becomes 45kts. And finally some of the most noted 'experts' (see at least two out of 4 of the authors we discussed way up the thread) don't even have wind instruments. . . . their judgment of wind speeds under 35kts is probably pretty accurate, but because it's so rare I doubt their judgment of wind over 50kts is very accurate. I see a lot of photos where people claim more than 60kts, and anyone who's actually been in 60kts can see immediately it's not . . . there is a 'phase change' and the water starts to smoke around then. So, even if the met wind speeds were useful (which as I suggest in 1 & 2 above I don't think they are), 'sailor wind speeds' are often quite different than the official met winds.

Attachment 60402

So IMHO, the official met definitions are pretty much useless in trying to discuss when to use which technique. You need to start with wave size and shape. But then you have to also add in a whole set of qualitative 'feel' factors.
Evans, I think we both agree that wave height and period will dictate strategy for any given vessel in an offshore scenario.

However, I still believe Beaufort Scale is relevant as it is an empirical measure for the intensity of the wind based mainly on sea-state or wave conditions, in offshore conditions.

In the old days or even now when your anemometer fails in a storm…. You are judging your wind strength by sea conditions in an offshore scenario

"The scale was created in 1806 by Sir Francis Beaufort, a British naval officer. The initial scale did not have wind speeds, but listed a set of qualitative conditions from 0 to 12 by how a naval vessel would act under them - from 'just sufficient to give steerage' to 'that which no canvas could withstand'. The scale was made a standard part of log entries for Royal Navy vessels in the late 1830s."

Beaufort Wind Force Scale and Sea State

While modern studies of sea states are fascinating in measuring and fine tuning patterns, as we both also agree,….a sailor in a Storm measures far more subjectively.

If as you say, some sailors cannot differentiate between sustained and gusts and tend to exaggerate, that is their problem and immaterial to this discussion.
There is no fooling breaking green seas upon you whether it be 2 or 20 in an hour
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