The Rogue wave and the sailor

[Dan Mosby]

While cruising through some sailing vids on the %$#@Tube, I ran across a video concerning the "Draupner Wave" of 1995, which was the first "rogue" wave ever documented thouroughly with any kind of measuring equipment.

The pic demonstrates that a rogue wave is 2 to 3 times greater than the "average" set of waves...which becomes problematic in an evironment with, say, 10 meter seas. That's 90 meters of Neptune's fury coming down on you with about 100 tons per m2 of force. Not good.

Apparently these giants are more likely to form when areas of strong ocean current encounters strong opposing winds. High latitudes are especially susceptible due to the rotating masses of air at the poles, which makes places like the north sea and both the southern capes especially dangerous. Combine the storm season with the gulf stream, or any similar stream in the pacific, and you have all the ingredients you need to experience a rogue wave at lower lats.

Since these things are capable of taking out super-tankers, cruise ships, and oil platforms, the traveler in the 40 foot yacht would be wise to plan their journeys extremely carefully around those parts of the ocean susceptible to strong currents and storm winds, as a 90 foot wave might just be a bit much for the ol' westsail 32.

Anybody ever encounter this phenomena personally? If so, where?

Be careful out there, and mindful of the current.

[LongRange]

The Perth Maritime Museum has a 90' high marker behind the statically displayed Parry Endeavour, to give some sense of the scale of the waves that Jon Sanders faced on his triple circumnavigation. It's like looking up at a small mountain.

Then again, I'm kinda scared of dying of a heart attack in the office, triggered by yet another corporate inanity, and in my case that is far, far more statistically probable than encountering 90' waves.

[Training Wheels]

90’ would be bad, but that 90 meter wave would really ruin your day!

[CassidyNZ]

I’m sure that Dan meant to say 90 feet not 90 metres.

Truth is that unless the wave is breaking, there is little danger to a 40ft sailing boat. The reason these waves are dangerous to shipping is because big ships span more than one swell and a rogue could confront the ship with irresistible forces.

But a small boat will go up 90ft then come down 90ft. There will no doubt be some skid marks around but unless it breaks, the rogue will probably be harmless. It’s the same with a tsunami which will pass under your boat at sea almost unnoticed but can destroy a complete city when it comes ashore.

Of course if the rogue does break, well, place your head firmly between your knees and kiss your . . . . . goodbye.

[fxykty]

Is it not wave length relative to the boat that causes problems and not the wave height, assuming the wave is not breaking? E.g. for the Southern Ocean with unlimited fetch the basic swells are 10-15m high and have wavelengths 200-400m. This won’t trouble a 300m long container ship, nor a 10m sailing vessel. But get a rogue wave 30-40m high on the same wave length and that container ship could break its back. The 10m sailing vessel just keeps sailing along. Hence Jon Sanders reports ginormous waves but certainly survived them.

None of this matters if the wave is breaking - then reportedly anything higher than half your beam can roll your boat. So lying ahull and broaching are activities to avoid in large breaking seas. Lying to a sea anchor or running with a drogue increases your ‘beam’ relative to the wave heights, and also decreases the transfer of wave energy to the boat, but even a 20m long boat is at risk when breaking waves increase in height to 10+m.

[Dan Mosby]

Originally Posted by Training Wheels

90’ would be bad, but that 90 meter wave would really ruin your day!

%#@!ing imperial/metric nonsense. That's what happens when you grow up in an environment where you carry pounds, walk kilometers, drive miles, and drink by the quart.

Madness.

[Dan Mosby]

Originally Posted by fxykty

Is it not wave length relative to the boat that causes problems and not the wave height, assuming the wave is not breaking? ....

Another characteristic of the "rogue" wave is how the shape becomes altered compared to the average. It's as if the crest is pulled straight up, which steepens the face and the backside of the wave. This is believed to cause the issue you describe, as the midship areas loses all support after breaking over the crest due to the huge trough that forms like a hole in the ocean between waves.

Pics:
1. Wall o' Water coming at ya.... Notice how shear the face is? That's just brutal.

2. Rogue wave decides to help with some enroute bow modifactions

Apparently 15 tons per m2 is the design goal for structural strength for most big cargo vessels, but new calculations have determined that the 100 ton per m2 is what it would take to defend from a breaking rogue. That's insane.

[IslandHopper]

Originally Posted by LongRange

The Perth Maritime Museum has a 90' high marker behind the statically displayed Parry Endeavour, to give some sense of the scale of the waves that Jon Sanders faced on his triple circumnavigation. It's like looking up at a small mountain.

Then again, I'm kinda scared of dying of a heart attack in the office, triggered by yet another corporate inanity, and in my case that is far, far more statistically probable than encountering 90' waves.

.....While on the foredeck he glimpses in the pre-dawn light a monstrous wave, descending on his yacht with a thunderous roar. He grabs the mast and hangs on for grim life as it cascades over him…

If you look towards the ceiling you will see the orange sea brake. Jon Sanders estimated that the wave was 30 metres high, the same height as the sea brake from the floor.....

Click >>>> 5. Parry Endeavour | Western Australian Museum

[Dan Mosby]

Originally Posted by IslandHopper

Click >>>> 5. Parry Endeavour | Western Australian Museum

This is why I buy brown foul weather pants.

[barnakiel]

I think that looking from the perspective of your Westsail deck, the wave does not need to be monstrous. It is just enough that it is rogue (in nature, shape, speed and relative height).


It takes a very small wave to overwhelm and damage a Westsail, flooding the boat and possibly killing the crew.


This is so because it takes a truly moderate wave to overpower a boat caught beam on. Such waves are present in every serious storm and they will pop up outside of storm conditions too.


I like to not think of rogue waves but rather concentrate on ODD waves. They are common enough to do worry if your boat is small enough.


We got wiped out twice in our (roughly) 600 ocean days. So in our case they are rogue once every 300 days. Boat 26' 3T.


A smaller boat will meet her rogue wave say once every 100 ocean days, a bigger one maybe once every 1000 days?


Beware. They are out there. They are watching you. ;-)


b.

[fxykty]

According to most oceanography reports that I’ve seen swell heights are like wind strength, the average wave height/wind strength is X and the occasional peak wave height is 2X and wind gust is 1.5X.

Good point that higher than average waves, including rogues, do not increase in period nor wave length and hence have (much) steeper faces and backs since the same volume of water needs to go higher. More likely to break as well than the surrounding average swells.

Bummer. But boat swallowing waves are, outside of select places, not common at all. On a mid-latitudes circumnavigation likely not at all. Rest easy, friends, rogue waves are not a reason to not go sailing.

[boatman61]

Well 7 Portuguese fishermen were rescued last week near the Azores after 3 days and 4 nights in a liferaft after two consecutive extra (rogue) large waves capsized and sank their 95ft fishing boat.

[newhaul]

Originally Posted by Dan Mosby

While cruising through some sailing vids on the %$#@Tube, I ran across a video concerning the "Draupner Wave" of 1995, which was the first "rogue" wave ever documented thouroughly with any kind of measuring equipment.

The pic demonstrates that a rogue wave is 2 to 3 times greater than the "average" set of waves...which becomes problematic in an evironment with, say, 10 meter seas. That's 90 meters of Neptune's fury coming down on you with about 100 tons per m2 of force. Not good.

Apparently these giants are more likely to form when areas of strong ocean current encounters strong opposing winds. High latitudes are especially susceptible due to the rotating masses of air at the poles, which makes places like the north sea and both the southern capes especially dangerous. Combine the storm season with the gulf stream, or any similar stream in the pacific, and you have all the ingredients you need to experience a rogue wave at lower lats.

Since these things are capable of taking out super-tankers, cruise ships, and oil platforms, the traveler in the 40 foot yacht would be wise to plan their journeys extremely carefully around those parts of the ocean susceptible to strong currents and storm winds, as a 90 foot wave might just be a bit much for the ol' westsail 32.

Anybody ever encounter this phenomena personally? If so, where?

Be careful out there, and mindful of the current.

1989 south China sea between two typhoons took a 50+ rogue head on solid water swept the flight deck really did some serious damage to the now requiring the whole now to be cut off and replaced.
Later that day had a 50 ft rogue take one of my men right off the ship . Very bad day indeed will never forget Donald Evans . I sent him out there to secure a leaking hatch on an ammo locker.
Really don't ever want to be in that kind of slop again .

[mabowers]

Originally Posted by newhaul

1989 south China sea between two typhoons took a 50+ rogue head on solid water swept the flight deck really did some serious damage to the now requiring the whole now to be cut off and replaced.
Later that day had a 50 ft rogue take one of my men right off the ship . Very bad day indeed will never forget Donald Evans . I sent him out there to secure a leaking hatch on an ammo locker.
Really don't ever want to be in that kind of slop again .

What ship ? In 89 on USS Carl Vinson we took one 70ft+, green water all the way back to the island. It stove in the 03 level above the focsle like God hit us with a ball peen hammer & a piece about the size of a billboard had to be cut out & replaced. I still remember how 100,000 tons of aircraft carrier rang like a tuning fork... Pacex89... good times.

[newhaul]

Originally Posted by mabowers

What ship ? In 89 on USS Carl Vinson we took one 70ft+, green water all the way back to the island. It stove in the 03 level above the focsle like God hit us with a ball peen hammer & a piece about the size of a billboard had to be cut out & replaced. I still remember how 100,000 tons of aircraft carrier rang like a tuning fork... Pacex89... good times.

not really good times for me in R1 division that trip .
I was the guy hanging over the bow on tellie cutting and resending the safety nets so we could launch aircraft .
You should have seen what those 30 inch I beams looked like in the focsle.

Donald was swept off the aft stbd ciwis alone in by a 50ftter.