Large Waves vs Rogue Waves

[John Nantz]

According to this article (http://news.yahoo.com/s/nm/20050804/us_nm/weather_hurricane_dc) very large waves are often called rogue waves; however, the authors feel "very large waves are actually fairly common during hurricanes". They said that Ivan sank seven oil platforms and set five adrift! Wonder how many of the platforms are just abandoned after being sunk? They also said that there are relatively few ships that have problems with these waves because they are smart enough not to be caught out in them. Now there's a thought.For info, one wave was measured at 105 feet off the southern tip of the Queen Charlottes, Cape St. James, in the fall of 1993 by a wave height measuring buoy.Anyway, the article was interesting to read so I thought I'd share it.

 

[Sailortom20832]

Rogue waves combination of two or more waves

I believe that a rogue wave results when two (or more) waves intersect in such a way that their size adds together to form a wave the size of both combined. Waves can also combine so that they actually cancel each other out, and the result is no wave at all. When wave systems intersect they can cause very confused seas as waves alternately cancel and add together. You can sometimes see this when two wake induced wave systems intersect. You'll have flat water followed by very steep waves, followed by flat water again. Imagine this on a larger scale when the normal wind induced waves intersect with say a hurricane induced wave from another direction.

 

[Bill O'Donovan]

Skeptical

90 feet qualifies as rogue in my book, but how is it we're finding out about this a year later? Surely it was news then, or did those platforms only recently go missing?

 

[Franklin]

rogue waves

are somewhat of a mistery but they do exists. These are different then waves from storms. As sailortom said, they are a result from two or more waves combining energy to form a hugh wave. Until that cruise ship got hit with one this past spring, many scientist didn't believe in them. From what I understand, the reason they are a mistery is because they don't last long.Now not much is known about waves in hurricanes because after all, not many people get caught up in one and even less live to tell about it, but I would be surprised that there weren't a lot of rogue waves near or in hurricane waters. I just hope we don't hear about one hitting a populated shore like the one that hit the cruise ship.

 

[Gary Wyngarden]

Thanks for sharing, John

Ninety feet, eh? We surfed down the face of a twelve footer off Estevan Point last month and hit 9.9 on the knotmeter. Ninety feet? I think I'd go below decks and put my head under the pillow!Gary WyngardenS/V Wanderlust h37.5

 

[jeff]

wave addition

I got caught out in the gulf in 50 knot winds once. The waves built to about 12' from the NW, but then the wind clocked to the NE overnight and waves started coming from that direction. I don't remember the relative calm periods, but the confused seas and occasional 20+' vertical tower of water taught me a thing or two about respecting the ocean. I remember repeatedly looking over at a wall of water and questioning "How are we ever going to get over that?"A ninety foot swell would be an experience, a ninety foot breaker would be tough to survive, a ninety foot box-shaped rogue would be death.

 

[Franklin]

90'

I bet if it's a rolling wave then you wouldn't have anything to worry about other then just being scared to death because unlike that cruiseliner, a sailboat would be light enough to ride up over the wave and since it's 90', it would be a smooth ride unlike going over a 6' wave where the hull smacks down. Now if it was breaking then you can just kiss you butt goodbye because that much water is going to break just about everything on the boat and no telling how long you will be under water and what your head will hit as everything goes tumbling around and around and around.

 

[Didereaux]

EU MaxWave project

http://www.seastead.org/localres/misc-articles/ESA_Rogue_Waves_07_21_04.htmlAs the EU project has proven rogue waves not only do exist, but in far greater numbers than predicted. The link above is an overview of the whole subject at present. This story made mainstream media earlier this year.

 

[Fine As Frogs Hair]

How about a 230 footer?

In the early 1970's part of a mountain broke off and slid into a bay in Alaska. There were about a dozen boats anchored in the bay, which was about 60 miles long and about 25 miles wide. When the mountain hit the water, it caused a "Tsunami" or Rouge Wave, or what-ever-you-want-to-call it, but it produced an initial wave of over 230 ft, and subsequnt waves of over 150 ft. The ordeal lasted less then 2 minutes. Of the boats anchored, only one made it through. It was a 55ft fishing boat with a father, and his son. Both are still alive today!The wave "cleared" any vegetation, including trees, off the sides of the bay from the site of the slide to the mouth of the bay. Because the mouth of the bay is relatively small, not much of the wave came through and what did, discipated within a few miles.90ft, that's a big wave! 230 ft, that is unbelievable. The story ran on the Discovery Channel a few months ago, just before the Tsunami hit the the Pacific!As for scientist not believing in Rouge waves, they need to check with the city of Daytona Beach, FL. Just two or three years ago, a Rouge wave came on shore and killed at least two people. If that aint a "smoking gun," I don't know what is! Paul

 

[Bob]

Flip side

Just as waves from two systems can coincide and essentially form a new wave with twice the amplitude, troughs can do the same. Ships and boats in confused seas have often reported waves of "pyramidal" shape that seem to rise up out of nowhere and last only a few seconds. Imagine if a trough formed the same way, from, say 3 distinct intersecting systems - it could be double or triple the depth of a normal trough. During WW2 a British cruiser off the coast of Durban reported the bow just 'dropping off a cliff', burying everything back to the second turret under green water. People in the forward parts of the cruiser thought they had been hit by a torpedo. That area is a notorious ship killer. I suspect that a small vessel could be in greater danger dropping into such a 'freak trough' than being hit by a 'freak wave'.

 

[NautiDuck]

My lake

is sounding better all the time. The only rogue we get there is Rogue Ale, a local micro-brew.

 

[Kevin]

Jeff, in case you missed it,

a youngster posted on here a week or so ago the he was looking to do a Gulf of Mexico crossing, and that he thought that is was not "really blue water". If I recall correctly, he was from the a northwestern state. I think that many of the people in the USA do not realize what the Gulf of Mexico is all about. Sure, it is not the Pacific Ocean, but it is a huge body of water, and certainly blue water, when you can be 500 miles from any land, in water over 3000 feet in depth, and some of the most dangerous weather on the planet.A good friend of mine has sailed from New Orleans to Cancun a few times in a 42 footer, and had a few frightening experiences. The Gulf of Mexico is not to be taken lightly!

 

[Jeff]

Yes, I saw that

Yes I saw that crack about the Gulf not really being blue water. I think that it may actually be worse than some oceans in similar wind/weather conditions because the waves tend to be much steeper. Given the choice between 30' swells in the ocean or 10' foot waves in the gulf, I'd take the swells any day.I don't know if it is because of our goofy weather patterns or because of the relatively shallow waters that extend dozens (hundreds?) of miles offshore, but the waves just get darn icky out there when the winds pipe up real good.Though wave size matters, a wave's shape is much more important. Thats why the rogues are so dangerous. They have roughly the same period as the underlining sets but twice the height and consequently twice the steepness. Some of the large waves that I've seen in confused seas have had virtually vertical faces and have given my boat quite a pounding. It feels similar to hitting a dock too fast and I'm surprised that the boat has survived such drubbings. Anyone want to buy a beat up Cherubini?

 

[Tom Monroe]

100 fathom line

I've been doing a lot of reading by world cruisers, and they keep talking about doing fine until they get at or inside of the 100 fathom depth contour line. Then the waves change shape pretty radically because part of their energy is contacting the bottom. Bottom of the wave slows down while the top keeps going, so the face gets steeper. Most of them seem willing to run off and stay at sea till a storm dies out rather than come inside the line.Given that, it's no wonder the gulf can be a challenge ... much of it ... and the part most people sail ... is inside the 100 fathom line.Tom MonroeCarlyle Lake(where 4-5 foot is the BIGGEST I've ever seen, and that only once)

 

[tom habanek]

heavy seas

Check out "heavy Seas'. The pics are awesome, and scary.

 

[Dennis]

Twice around

Years ago, I remember reading a great story entitled "Twice Around in Adios", about a man who took his Tahiti Ketch two times around the world. Anyway during one attempt, he got into a storm and said the waves were 60 feet over his boat! His boat actually got rolled and righted itself. Incredible!

 

[Dennis]

Just one question?

Just one more thing! How do guys or gals, sail around the world in 12 footers with waves like this?

 

[Jim Seamans]

Heavy Seas link

This will make you stay in port....Jim

 

[BobW]

I suspect they miss them!

12 feet is pretty long for a 'micro-boat' crossing of the Atlantic. The attached link is to a site I found that lists famous small boat voyages. Check out the picture..... does this look very safe or smart? But he made it.... and wrote a book, of course!!Another source of 'rogue' waves that's been reported is uncharted sea mounts. There's supposed to be several off the west coast of South Africa that almost reach the surface and cause breaking waves. If I recall, Beth Lonard reported alomst being capsized by an unexpected wave in that area. I've read of several other accounts like that.Recommended reading for those interested in rough weather and waves:Surviving the Storm, Linda and Steve Dashew, Beowulf PressScared me silly on first reading, then provided much food for thought.Cheers,Bobs/v X SAIL R 8

 

[JC on Bainbridge]

Tom, where are the "Heavy Seas" pics?

If you can give us the link, that would be great.Friends of mine has gone between Alaska and Seattle many times. Large swells are not really the same as a rogue wave. During their Alaska trips, they have encountered wall of water higher than their stick, and their stick is about 52'. The worst part was when the top of the water gets blown over and comes down into the cockpit. Just before the cockpit water drains out, the next load drops in. Live with that for 4 or 5 hours, you will be exhusted long before the storm is over.In most cases, the boat will take care of itself, and will survive a lot better than us humans.As to how a boat survives in huge swells, well, it bobs like a cork.