Huge Waves Tracked Off Lewis

[Cookie]

http://www.bbc.co.uk/news/uk-scotland-highlands-islands-15172793

Waves said to be twice the normal height expected off a Western Isles coast have been recorded.

The rollers of more than 15m (49ft) occurred during gales on Monday.

They were measured by devices called wave rider buoys, that were installed off north west Lewis as part of a renewable energy project.

Lews Castle College UHI, which is involved in the project, said the waves came as winds peaked at 66mph (106 km/h).

The buoys, part of the Hebridean Marine Energy Futures scheme, recorded the waves about five nautical miles off Lewis.

Lews Castle College UHI said it was the first time giant waves have been accurately recorded off the Western Isles.

Project leader Arne Vogler said: "The occurrence of 15m waves - the height of a four-storey building - after half-a-day of severe gale force winds indicates that much higher waves are likely to occur during prolonged storm periods which are often encountered in the area between autumn and spring.

"The ability to measure these kind of events will allow us to gather invaluable baseline data which can be used to assess impacts of climate change and changes of seabed use."

Radio link

The buoys were installed at the end of September.

They are the first stage in a wave data observatory network and transmit live data through a radio link to the shore station.

In February, waves towering to 15.9m (52ft) were recorded by the Met Office in the sea off Shetland during stormy weather.

Equipment on a buoy called K7 recorded the huge waves.

The National Oceanography Centre in Southampton said waves that height were recorded once in 20 years.

[knocker]

This comes as no surprise to me. In days of yon seafarers tales of huge abnormal waves were dismissed out of hand, basically because theory of wave structure didn't support the observation. That is until an oceanographer whose name escapes me at the moment proved that the calculations were incorrect. It is now fully accepted that given the right conditions which include, if I remember correctly, having huge cross swells as well as wind waves, these 'rogue' waves most certainly do occur. I suspect one was responsible for the sinking of the trawler Gaul.

Measuring of waves went on for many years on ocean weather ships ( and other ships), using pressure pads on the hull. I was on a ship that measured an 86ft wave near Rockhall longer ago than I care to remember. There is some quite interesting info. on unusual sea conditions in the Fastnet thread in the history section.

Some of the most dramatic photos I've seen were the ones by Jean Guichard of the La Jument lighthouse during a huge storm in 1989.

http://celticcountries.com/magazine/culture/la-jument-brittany-most-famous-lighthouse/

[Cookie]

Nice link thanks for sharing, what grabs may attention straight away is the fact this was only a small storm and nothing compared to what we get the rest of the year some of the those waves heights must be massive!

[knocker]

Nice link thanks for sharing, what grabs may attention straight away is the fact this was only a small storm and nothing compared to what we get the rest of the year some of the those waves heights must be massive!

That's what perplexed many about the Fastnet. It was fairly severe but so many ocean going yachts, shouldn't in theory, have been lost.

[knocker]

Just an observation but if you on a small ship in a trough looking up at a 70-80ft wall of water (because that's what it is), it's both awesome and bloody scary. Not quite as scary as trying to launch a radiosonde in that weather: that's without doubt a three underpants job. Well I'm off to get the violin out.

[Cookie]

Just an observation but if you on a small ship in a trough looking up at a 70-80ft wall of water (because that's what it is), it's both awesome and bloody scary. Not quite as scary as trying to launch a radiosonde in that weather: that's without doubt a three underpants job. Well I'm off to get the violin out.

reminds me a little of the film the perfect storm and the size of the waves portrayed in that and I can fully understand how that would both be awesome and scary as anything at the same time!

[wimblettben]

This comes as no surprise to me. In days of yon seafarers tales of huge abnormal waves were dismissed out of hand, basically because theory of wave structure didn't support the observation. That is until an oceanographer whose name escapes me at the moment proved that the calculations were incorrect. It is now fully accepted that given the right conditions which include, if I remember correctly, having huge cross swells as well as wind waves, these 'rogue' waves most certainly do occur. I suspect one was responsible for the sinking of the trawler Gaul.

Measuring of waves went on for many years on ocean weather ships ( and other ships), using pressure pads on the hull. I was on a ship that measured an 86ft wave near Rockhall longer ago than I care to remember. There is some quite interesting info. on unusual sea conditions in the Fastnet thread in the history section.

Some of the most dramatic photos I've seen were the ones by Jean Guichard of the La Jument lighthouse during a huge storm in 1989.

http://celticcountri...ous-lighthouse/

Blimey thats a big wave!

[bobbydog]

a friend of mine got a job on the QE2 a few years back, as a band member. however his start date was delayed as the ship had to go in for repairs after a giant wave in mid Atlantic, bent the bow!

[Cookie]

this always reminds me off this

[johnholmes]

Just an observation but if you on a small ship in a trough looking up at a 70-80ft wall of water (because that's what it is), it's both awesome and bloody scary. Not quite as scary as trying to launch a radiosonde in that weather: that's without doubt a three underpants job. Well I'm off to get the violin out.

I've told you before Fred you have to be bloody daft to have done that job but it takes all sorts!

[Turnedoutniceagain]

Blimey thats a big wave!

The bloke stood by the door having a cheeky Gaulois cracks me up !!

[knocker]

Talking about cracking up reminds me that I had unfortunate experience of sailing under two skippers, one who should have been in rehab and the other a secure unit. The former had a special chair made in his cabin, securely bolted to the floor, with fiddles where he could keep his bottle of gin and a glass.

One evening during a force11-12 it got ripped off the deck and both he and the chair were smashed against the bulkhead with the result he severely injured his shoulder. In those days we used to get medical advice from the Luton and Dunstable hospital. We duly sent a message describing the symptoms. The doctor queried, "have you tried manual traction?", to which the skipper replied, " we don't carry that equipment on board". I shudder to think about what the nutcase did. Suffice it to say he never sailed again. I really must put the violin away.

Edited October 7, 2011 by weather ship

[Interitus]

Nice link thanks for sharing, what grabs may attention straight away is the fact this was only a small storm and nothing compared to what we get the rest of the year some of the those waves heights must be massive!

Of course the wave heights are not purely a function of wind speed but also the fetch and duration so a large storm may not necessarily produce the largest waves.

For comparison, the highest waves as measured by a buoy is 18.275 metres (59.96 feet) by the Met Office's buoy K3 on 08/12/2007

http://wmo.asu.edu/World-Highest-Wave-Buoy

However the Royal Research Ship Discovery measured waves of 18.5 metres in area of the Rockall trough in February 2000

For those that might not know, this was the significant wave height measured over half an hour, indivdual waves reached a maximum of 29.1 metres or over 95 feet

http://www.noc.soton.ac.uk/obe/PROJECTS/EEL/weather.php

Buoy and satellite altimetry data give an estimated wave height off the Hebrides of 16 and 18 metres with a return time of 50 years.

This rises to in excess of 20 metres for Rockall and the mid-Atlantic.

http://mail.hsebooks.com/research/othpdf/200-399/oth396.pdf

More recent satellite data show 100 year return values up to 25 metres in the north Atlantic within a region of 20 metre values reaching as far as the North Sea suggesting this is the roughest sea area on the planet.

http://202.114.89.60/resource/pdf/2606.pdf

[knocker]

Of course the wave heights are not purely a function of wind speed but also the fetch and duration so a large storm may not necessarily produce the largest waves.

Don't forget period. This is precisely why scientists classify waves as being free or forced based on whether they ever get free of the force that generates them. All waves are forced to begin with but most become free shortly after their formation. Wind waves naturally, unlike tidal waves that remain forced. And it can get slightly more complicated than that. See post #2 with reference to the Fastnet disaster.

http://forum.netweat...15#entry1874415

Edited October 7, 2011 by weather ship

[knocker]

Of course the wave heights are not purely a function of wind speed but also the fetch and duration so a large storm may not necessarily produce the largest waves.

Don't forget period. And of course this is why scientists classify waves as being free or forced, based on whether they ever get free of the the force that generates them. All waves are forced to begin with, but most become free shortly after their formation. As against a tidal wave which remains a forced wave. But it can get more complicated than that see posting #2 in the Fastnet thread.

http://forum.netweather.tv/topic/56383-the-fastnet-race-disaster/page__pid__1874415#entry1874415

[Guest mycroft]

Of course the wave heights are not purely a function of wind speed but also the fetch and duration so a large storm may not necessarily produce the largest waves.

For comparison, the highest waves as measured by a buoy is 18.275 metres (59.96 feet) by the Met Office's buoy K3 on 08/12/2007

http://wmo.asu.edu/W...ghest-Wave-Buoy

However the Royal Research Ship Discovery measured waves of 18.5 metres in area of the Rockall trough in February 2000

For those that might not know, this was the significant wave height measured over half an hour, indivdual waves reached a maximum of 29.1 metres or over 95 feet

http://www.noc.soton...EEL/weather.php

Buoy and satellite altimetry data give an estimated wave height off the Hebrides of 16 and 18 metres with a return time of 50 years.

This rises to in excess of 20 metres for Rockall and the mid-Atlantic.

http://mail.hsebooks...-399/oth396.pdf

More recent satellite data show 100 year return values up to 25 metres in the north Atlantic within a region of 20 metre values reaching as far as the North Sea suggesting this is the roughest sea area on the planet.

http://202.114.89.60...ce/pdf/2606.pdf

i would of thought that the southern ocean as the roughest ocean on the planet, where 30 meter wave have often reported using global satellite radar surveillance.

BBC Horizon programme called Freak Wave found many instances of 30 mtr waves which in theory the laws of physics say should not be possible for wind blown waves.

Detail of programme can be found here including a full transcript.think you might find the programme on youtube instead of down loading it from here

http://www.bbc.co.uk...freakwave.shtml

Edited October 7, 2011 by mycroft

[knocker]

i would of thought that the southern ocean as the roughest ocean on the planet, where 30 meter wave have often reported using global satellite radar surveillance.

BBC Horizon programme called Freak Wave found many instances of 30 mtr waves which in theory the laws of physics say should not be possible for wind blown waves.

Detail of programme can be found here including a full transcript.think you might find the programme on youtube instead of down loading it from here

http://www.bbc.co.uk...freakwave.shtml

I remember seeing that programme, particularly the cruise liner. Regarding currents I believe there are a propensity of large waves around the Horn of Africa where the strong Agulhes current runs NE-to SE (roughly).

Clearly, there was another effect investigators needed to find. Except someone already had: it existed (on paper at least) in the world of quantum physics. Al Osborne is a wave mathematician with 30 years experience devising equations to describe open ocean wave patterns.

That's the chap whose name escaped me in my first post.

Edited October 8, 2011 by weather ship

[Alan Robinson]

a friend of mine got a job on the QE2 a few years back, as a band member. however his start date was delayed as the ship had to go in for repairs after a giant wave in mid Atlantic, bent the bow!

That sort of thing happens regularly. I saw an AFRAMAX tanker with its wavebreaker laid flat on the foredeck.

The problem I have with vessels like the QE2 is however not steel structure, but big windows. Loadline regulations require that windows in certain locations must be provided with storm shutters for use in the event of glazing failure. Some windows are made pretty big however for aesthetic reasons, and storm shutters are not practical. For this reason authorities might dispensate by dropping the storm shutter requirement provided the glass thickness is suitably increased.

All very well, except shipbuilders - in their attempt to cut costs - have more recently been allowed to use glass polished using acid (to reduce the risk of cracking) instead of heat-treated safety glass. Again, all very well one might say, until the glass receives micro-scratches, undoing the effect of acid polishing and leaving the window inferior to the traditionally required safety glass.

Waves do not have to be so high to cause a problem........

incidentally, here is the same ship in Greenland...

I can just imagine a wave coming green over the bow and taking a large piece of ice with it up to the Wheelhouse front windows...

Edited October 8, 2011 by Alan Robinson

[Alan Robinson]

Talking about cracking up reminds me that I had unfortunate experience of sailing under two skippers, one who should have been in rehab and the other a secure unit. The former had a special chair made in his cabin, securely bolted to the floor, with fiddles where he could keep his bottle of gin and a glass.

One evening during a force11-12 it got ripped off the deck and both he and the chair were smashed against the bulkhead with the result he severely injured his shoulder. In those days we used to get medical advice from the Luton and Dunstable hospital. We duly sent a message describing the symptoms. The doctor queried, "have you tried manual traction?", to which the skipper replied, " we don't carry that equipment on board". I shudder to think about what the nutcase did. Suffice it to say he never sailed again. I really must put the violin away.

Here you see m v Magnus Jensen in 1982. I worked on re-building the ship, which really ought to have been scrapped.

Magnus Jensen got into this state by running over a reef south of Cape Farewell, approaching Greenland December 1981, loaded with all kinds of Christmas goodies, ski scooters and whatnot. Rumour at the shipyard was that when the ship struck the reef there was nobody on watch; all were said to be revelling. Whether true or not I cannot say.

By the way, there are plenty of good, entertaining accounts here...http://www.maib.gov.uk/home/index.cfm

Don't forget period. This is precisely why scientists classify waves as being free or forced based on whether they ever get free of the force that generates them. All waves are forced to begin with but most become free shortly after their formation. Wind waves naturally, unlike tidal waves that remain forced. And it can get slightly more complicated than that. See post #2 with reference to the Fastnet disaster.

http://forum.netweat...15#entry1874415

Then there is the difference between swell and sea. Seas are sumperimposed on swell, and in any case, there can quite easily be two swells from different directions in any one location, which also superimpose. It really is a complex subject.

Regarding the Fastnet, I do not want to get going about racing and good seamanship, but I'd just say I would never personally set out if the forecast is for force 7 or more. Getting caught out is however different, and it can be a good idea sometimes to head away from land. For example, I caution all humanity against approaching Cuxhaven from seaward aboard a small vessel if the spring ebb is running and the wind is NW force 6.

[Interitus]

Don't forget period. This is precisely why scientists classify waves as being free or forced based on whether they ever get free of the force that generates them. All waves are forced to begin with but most become free shortly after their formation. Wind waves naturally, unlike tidal waves that remain forced. And it can get slightly more complicated than that. See post #2 with reference to the Fastnet disaster.

http://forum.netweat...15#entry1874415

Something similar was suggested for the waves reported by the RRS Discovery where a resonance was established between the motion of a frontal system matching the velocity of the waves. The mean wind speeds were not extreme at 21m/s (47mph) but the conditions persisted for two days.

The 18.5m significant wave height (SWH) is higher than any previously published wave data and this excellent article entitled "Were extreme waves in the Rockall Trough the largest ever recorded?" covers it in detail - http://xpda.com/junk...005GL025238.pdf

The previous highest instrument wave height for the Rockall region was 26.3m from a SWH of 15.7m. For comparison waves recorded from Hurricane Ivan in 2004 had a peak of 27.7m and a SWH of 17.9m.

i would of thought that the southern ocean as the roughest ocean on the planet, where 30 meter wave have often reported using global satellite radar surveillance.

BBC Horizon programme called Freak Wave found many instances of 30 mtr waves which in theory the laws of physics say should not be possible for wind blown waves.

Detail of programme can be found here including a full transcript.think you might find the programme on youtube instead of down loading it from here

http://www.bbc.co.uk...freakwave.shtml

I feel it is important to differentiate between freak, rogue or 'hundred year' waves and those described above. The RSS Discovery recorded 23 waves over 20m with a maximum of 29.1m.

Hindcasting suggests a 30 metre wave as having a 100 year return time for this location

[knocker]

Something similar was suggested for the waves reported by the RRS Discovery where a resonance was established between the motion of a frontal system matching the velocity of the waves. The mean wind speeds were not extreme at 21m/s (47mph) but the conditions persisted for two days.

The 18.5m significant wave height (SWH) is higher than any previously published wave data and this excellent article entitled "Were extreme waves in the Rockall Trough the largest ever recorded?" covers it in detail - http://xpda.com/junk...005GL025238.pdf

The previous highest instrument wave height for the Rockall region was 26.3m from a SWH of 15.7m. For comparison waves recorded from Hurricane Ivan in 2004 had a peak of 27.7m and a SWH of 17.9m.

An interesting read although there are some important differences between it and the Fastnet paper which I can't find at the moment. One thing it did do was clarify my memory which has been deteriorating since I passed 20.

In an earlier post I mentioned the 26.3m wave, but I got the wrong ship as the Reporter was on weather station 'India' at the time. The one I recollect was on the Weather Adviser and measured 25.6m unless Laurie Draper adjusted it slightly. That was definately somewhere around Rockhall and would have been about the same period.

Just to make a general observation about waves (not aimed at yourself)because sometimes there is some confusion about this.

Waves are travelling oscillations that can transfer energy over large distances, even though the water itself goes nowhere. It just oscillates as the waves pass by. If you are in an orbital wave you will be more or less be carried around in a circle. This is not meant to sound patronizing folks.

Edited October 8, 2011 by weather ship

[Alan Robinson]

If you are in an orbital wave you will be more or less be carried around in a circle. This is not meant to sound patronizing folks.

Somebody is bound to come along and put "what a load of trochoid".

Edited October 8, 2011 by Alan Robinson

[knocker]

Somebody is bound to come along and put "what a load of trochoid".

Well I can always tell them "to go roll a hoop".