Rogue wave height and frequency?

sarabande

Well-known member
Joined
6 May 2005
Messages
35,989
Visit site
Yes, off St Catherines, 1974. In a RORC race we dropped a 42ft racer when a hole about 12 ft deep appeared underneath the boat. A big bang and one of the internal bulkheads ( a honeycombe/aluminium structure used in aircraft) showed a transverse distortion 'wrinkle' as witness to the twisting the hull had experienced. The aluminium hull itself showed no distortion when we clipped after completing the race a few days later; I guess it experienced only elastic deformation.

I think we missed the wave, and experienced the trough. Perhaps troughs are as dangerous as waves ?
 

r_h

Active member
Joined
5 Jun 2006
Messages
663
Location
West coast France, Solent + E. Med
www.rupertholmes.co.uk

fisherman

Well-known member
Joined
2 Dec 2005
Messages
19,675
Location
Far S. Cornwall
Visit site
Years ago N Sea fishermen complained about huge waves in the vicinity of oil rigs, nicknamed it the ‘Lloyd’s Drop Test’. There was some conjecture about micro weather systems near the gas flares, but it doesn’t really stack up.
Certainly I have witnessed the odd out of the ordinary swell or wave, at sea and ashore. There can be situations with two different wave frequencies where waves from both get together.
Not always a problem, I have happily hauled gear in swells of 48feet max, measured on the fish finder. Flat calm apart from the swell, but had a hand on the winch lever.
 

lpdsn

New member
Joined
3 Apr 2009
Messages
5,467
Visit site
I think we missed the wave, and experienced the trough. Perhaps troughs are as dangerous as waves ?

Had similar in the Irish Sea. Trying to do a trip in a tight window between two gales and got caught by the second. Was OK till we came over the top of one wave and found a hole about 25 - 30' deep. when we hit the wave on the other side it smashed the radar reflector, which was just below the first spreaders. Anchor pin was also washed out so I had to sail very defensively for the next 45 mins as I didn't fancy sending anyone forward in case we encountered a similar wave/hole.

That said, I'm not sure anyone except a journalist can say they're becoming more frequent as I don't believe that was sufficient accurate data previously for any meaningful comparison.
 

Biggles Wader

Well-known member
Joined
3 Mar 2013
Messages
10,832
Location
London
Visit site
Yes once. On a 12000 ton cargo ship in the South Atlantic we were weathering a big storm slow steaming into the wind. The waves were generally enormous----standing on the bridge wing about 40ft high I was looking up at the wave tops which were almost as high again. Then we were overwhelmed by one huge growler which swept the ship end to end. You have to experience the shuddering and shaking of a big ship trying to surface again after being "sunk" like that. A fair bit of damage was done.
 

GHA

Well-known member
Joined
26 Jun 2013
Messages
12,383
Location
Hopefully somewhere warm
Visit site
.
That said, I'm not sure anyone except a journalist can say they're becoming more frequent as I don't believe that was sufficient accurate data previously for any meaningful comparison.

The data points towards the height increasing, not the frequency.
https://www.nature.com/articles/s41598-019-41099-z



We use time series of continuous surface elevation over 124–270 months (spanning 1994–2016), from 15 wave buoys along the US western seaboard, to investigate regional trends in significant wave height and individual rogue waves
 

bbg

Active member
Joined
2 May 2005
Messages
6,780
Visit site
Years ago N Sea fishermen complained about huge waves in the vicinity of oil rigs, nicknamed it the ‘Lloyd’s Drop Test’. There was some conjecture about micro weather systems near the gas flares, but it doesn’t really stack up.
I can believe that the wave trains are bent slightly by oil rigs, meaning that down-swell (did I just invent a word?) of the rigs, the swells are no longer running parallel, but that some of them are slightly crossing each other. That could cause an area with higher (or lower) swells then one might find up-swell of the rig.
Just a thought.
 

fisherman

Well-known member
Joined
2 Dec 2005
Messages
19,675
Location
Far S. Cornwall
Visit site
I can believe that the wave trains are bent slightly by oil rigs, meaning that down-swell (did I just invent a word?) of the rigs, the swells are no longer running parallel, but that some of them are slightly crossing each other. That could cause an area with higher (or lower) swells then one might find up-swell of the rig.
Just a thought.

That is most definitely a 'thing' when wave train gets 'bent' round a headland and meets another. Couple of nice spots close off the Lizard like that.
 

mm42

Active member
Joined
9 Sep 2014
Messages
380
Location
North of England
Visit site
I’d started a new boat and had the company fleet superintendent out for a quick check before signing me off.

We were in an 11 metre cabin rib off Aberdeen and sitting in 2-3 metre swells, nothing for that boat. The superintendent was on the phone when a big one came out of nowhere, very quick, very sharp, and a good 6-7 metres. We rode up it and just fell off the back side. Landed with a bang, a quick systems check and all was in order, we scampered home for the afternoon.

He was quite shaken by the unpredictability of it, I’ll be honest I quite enjoyed the adventure.
 

lpdsn

New member
Joined
3 Apr 2009
Messages
5,467
Visit site
The data points towards the height increasing, not the frequency.
https://www.nature.com/articles/s41598-019-41099-z

Interesting. The data is pointing towards several things in that study in that area. Interesting that it's pointing towards a slight reduction in significant wave height as well as larger big waves. To me it's saying the data is pointing towards there not being enough data yet. It's also the sort of thing where you want to probe into whether there have been changes in the instrumentation over the period that have improved the ability to detect exceptional waves. Of course, never enough time. Still, very interesting, but I'm not panicking yet.
 

KellysEye

Active member
Joined
23 Jul 2006
Messages
12,695
Location
Emsworth Hants
www.kellyseye.net
We had to deliver a charter boat back to base in St Martin and when we did there was a gale, we encountered a wave that had nothing behind it and the bows went down until the water reached the mast. Luckily the forward hatch wasn't torn off if it had we would have sunk.
 

ffiill

Active member
Joined
5 Sep 2007
Messages
3,283
Visit site
Whilst in the RAF during the war my dad made two return trips to Iceland.
On one of the trips they were on one of the old 4 funnel American Liners powered by black stokers shoveling coal.
Whilst in a severe storm he managed unofficially to get on deck to see the waves coming in above the funnels-amere 50 foot perhaps but scary non the less.
There have been studies of rougue waves in the North sea with data obtained from oil rigs and 100 foot plus ones are surprisingly frequent.
Both Shackleton in his 30 foot lifeboat and Chichester in Gypsy Moth experienced them as did the passenger sailing Clippers many of which did not live to tell the tale.
 

Robert Wilson

Well-known member
Joined
23 May 2012
Messages
7,975
Location
Second Coast, Ross-shire, overlooking Gruinard Bay
Visit site
Has anyone experienced a significant rogue wave when sailing, it appears that they are increasing in height if not frequency of occurrence.

https://www.bbc.com/news/science-environment-47642346

I understand that it is the combination of 2 or more swell's from differnt angles that seem's to cause them.

Interesting (to me)
Certainly not a significant one, as you put it, but in my first year owning Khamsin (9m sloop 1970s era) I sailed across the mouth of Little Loch Broom in a fairly wild SWly. Going well, in notable but not dangerous quartering seas, I suddenly "dropped into a hole". Left my stomach up by the spreaders and nearly filled my underpants with the noise of the thump.

It had never happened to me before, or since, and I was left wondering if I imagined it.

This thread may have helped prove me not quite so dippy :encouragement:
 

Robert Wilson

Well-known member
Joined
23 May 2012
Messages
7,975
Location
Second Coast, Ross-shire, overlooking Gruinard Bay
Visit site
Just read the report.
If the enquiry's finding is indeed the cause, then surely there must have been an unquantified period "of flooding" - so why no distress call in that period?

I always understood it was catastrophic failure at frame 65 (?) so the ship broke in two and sank like a stone.
I am only going by accounts and have no specialist knowledge of these matters.
 
Top