Southern ocean wave heights.

[DumnMad]

A new wave buoy measures a 20m wave and they expect bigger ones yet to be measured.

Oh buoy! Southern Hemisphere's largest wave recorded by Kiwi scientists | Stuff.co.nz

[S/V Illusion]

Don't let that news get out. Shackleton and Worley might not make it

[Snowpetrel]

I once saw a horrifying hole in the ocean in winter crossing the Aussie bight on a container ship. It was blowing a good force 10, with fully developed seas. Not really nasty for a 220 meter container ship, but we were slowed to about 8 knots semi hove too. I was on watch as a Third Mate when I saw this really odd shaped wave/trough to starboard of us. It must have been at least 60 foot deep, with what seemed like nearly vertical faces and no breaking crest. The spume/foam seemed to be running up the face in a weird reverse waterfall. I only caught a glimpse and it was gone, somewhere behind an to starboard of our ship. But the image has been seered into my mind for ever.

Somehow this hole in ocean seemed to defy the laws of physics. At the time it seemed to me that the centrifugal forces inside the wave were stopping it from collapsing. Who knows, I hope science will oneday be better able to explain these things.

Hopefully sceince will also be able to better predict conditions and areas that have higher chances of encountering rogues and extremely confused sea states, and warn us seafarers in time for us to avoid these areas.

My thoughts at the moment are to be concerned areas of;

-Dynamic fetch scenarios, where the wave height can rapidly increase far faster than the normal fetch, time, wind graphs show.

-Underwater topography such as seamounts and steep sections of the continental shelf where fast subsea currents can upwell causing chaos at the surface.

-Islands and underwater topography that can cause internal waves to superimpose and prehaps break underwater, possibly causing effects at the surface.

-The meandering and eddy's of ocean currents (look at windyTV currents) that can quickly cause a safe sea with wind and current aligned to suddenly switch and become wind against current.

Sadly I didn't log the position where we encountered that monster wave/hole. Possibly it was somewhere near the shelf , but if so we must have gone north of the Rhumb Line a fair ways.

Since then I have seen, and been knocked down by a few rogue waves, but nothing as big as that monster in the Aussie bight thankfully.

[DumnMad]

23.8 metres high this week.

https://www.nzherald.co.nz/nz/news/a...ectid=12048176

[Wotname]

Surf's up

[Chas.7]

Originally Posted by Wotname

Surf's up

Hello,
Based on studies, once a wave is 30% of the lenght of a boat your in a dangerous situation.
Good luck

[Steadman Uhlich]

Originally Posted by Snowpetrel

I once saw a horrifying hole in the ocean in winter crossing the Aussie bight on a container ship. It was blowing a good force 10, with fully developed seas. Not really nasty for a 220 meter container ship, but we were slowed to about 8 knots semi hove too. I was on watch as a Third Mate when I saw this really odd shaped wave/trough to starboard of us. It must have been at least 60 foot deep, with what seemed like nearly vertical faces and no breaking crest. The spume/foam seemed to be running up the face in a weird reverse waterfall. I only caught a glimpse and it was gone, somewhere behind an to starboard of our ship. But the image has been seered into my mind for ever.

Somehow this hole in ocean seemed to defy the laws of physics. At the time it seemed to me that the centrifugal forces inside the wave were stopping it from collapsing. Who knows, I hope science will oneday be better able to explain these things.

Hopefully sceince will also be able to better predict conditions and areas that have higher chances of encountering rogues and extremely confused sea states, and warn us seafarers in time for us to avoid these areas.

My thoughts at the moment are to be concerned areas of;

-Dynamic fetch scenarios, where the wave height can rapidly increase far faster than the normal fetch, time, wind graphs show.

-Underwater topography such as seamounts and steep sections of the continental shelf where fast subsea currents can upwell causing chaos at the surface.

-Islands and underwater topography that can cause internal waves to superimpose and prehaps break underwater, possibly causing effects at the surface.

-The meandering and eddy's of ocean currents (look at windyTV currents) that can quickly cause a safe sea with wind and current aligned to suddenly switch and become wind against current.

Sadly I didn't log the position where we encountered that monster wave/hole. Possibly it was somewhere near the shelf , but if so we must have gone north of the Rhumb Line a fair ways.

Since then I have seen, and been knocked down by a few rogue waves, but nothing as big as that monster in the Aussie bight thankfully.

Thank you for sharing your experience and anecdote in detail.

A wave that big, seen from any ship or boat, would be truly AWESOME and scary. Something I would only want to see from the bridge of a large vessel.

[TJ D]

Originally Posted by Steadman Uhlich

Thank you for sharing your experience and anecdote in detail.

A wave that big, seen from any ship or boat, would be truly AWESOME and scary. Something I would only want to see from the bridge of a large vessel.

Horsepower and tonnage are your best friends when things really go south out there, that's for sure.

[TeddyDiver]

Originally Posted by Chas.7

Hello,
Based on studies, once a wave is 30% of the lenght of a boat your in a dangerous situation.
Good luck

Hold you on to your hot coffee not to spill it on your pants, that's the real life danger (outside of the research chamber that is )

Teddy

[Mariano]

Originally Posted by Chas.7

Hello,
Based on studies, once a wave is 30% of the lenght of a boat your in a dangerous situation.
Good luck

Ok , you got me, I've been in a dangerous situation 20/30 times a year for the last 8 years........[emoji54] (30% of 46 is 15, not that of a big wave offshore)

[DumnMad]

Originally Posted by Mariano

Ok , you got me, I've been in a dangerous situation 20/30 times a year for the last 8 years........[emoji54] (30% of 46 is 15, not that of a big wave offshore)

Yes I'm thinking that 30% figure only applies to the breaking part of the wave which is very dependent on wind speed.

On one trip we had 20ft - 25ft rollers which had travelled hundreds of miles and were quite benign.

[Chas.7]

Hello,
I was once in a storm off Diamond Shoals at Hatteras on a tender ship. The waves were like mountains, the ship’s propellers came out of the water. Once the helmsman lost control of the bow. I thought the ship was not going to right itself. It did, but the hull was cracked. We put in to Charleston making a 1/2 knot.
Chas

[Chas.7]

That ship was the FS411 177 ft. A sister ship to the Pueblo, with the same house design. She was originally a two hatch coastal freighter. I was on a training mission but we seem to by following the Russian fishing fleet,
Chas

[Chas.7]

Hello,
I was once in a storm off Diamond Shoals at Hatteras on a tender ship. The waves were like mountains, the ship’s propellers came out of the water. Once the helmsman lost control of the bow. I thought the ship was not going to right itself. It did, but the hull was cracked. We put in to Charleston making a 1/2 knot.
Chas

[BruceS]

That's almost unbelievable!
My kids used to squeal & cry when I pulled the bath plug!!