When Good Waves Go Rogue

[SaltyMonkey]

New article on rogues:

When Good Waves Go Rogue - Issue 15: Turbulence - Nautilus

Don't look behind you!

[atoll]

experinced one once off the coast of columbia,was hand steering down wind at the time in 40 knot winds,heard it coming a good minute before it hit the boat,was probably 3 times larger and steeper than what we had been getting.

[SaltyMonkey]

Damn Atoll. Was there any significant weather over that period and where were you in relation to that?

EDIT 40knts was high but interested in what else was around you and for how long.

The video in the article is interesting, although I dare say I am not a pirate with a cannon on deck.

[atoll]

Originally Posted by SaltyMonkey

Damn Atoll. Was there any significant weather over that period and where were you in relation to that?

EDIT 40knts was high but interested in what else was around you and for how long.

The video in the article is interesting, although I dare say I am not a pirate with a cannon on deck.

tis pretty normal weather for that baranquilla peninsula where the north easterly trades been blowin all the way from the sahara.

guess it must be sumit to do with mojo.......

[SaltyMonkey]

Ja or you be in one giant test tank

[barnakiel]

Ours came from cross interference.

Amazing thing is that cross interference is also common in trains that move in the same direction. 1212121212121212121212126(sic!!!)12121212 pattern

Horror.

THX for sharing, will read up asap.

barnakiel

[Ex-Calif]

Whenever I hear about a rogue wave knockdown in moderate conditions (I view anything up to 40kts moderate/expected) I always start thinking.

- Was a proper watch being made by a trained crew or was this really a single handed trip with the S/O as a "casual" sailor and no one except otto was steering the boat.

The couple/crew never fesses up but I believe in a vast majority of cases there are no hands on deck, sails are shorted for the night and while the skipper may be in the cockpit he is likely asleep and not steering.

Crewed knockdowns (races for example) always seem to be related to severe weather that overwhelms crew and boat.

[Pelagic]

Interesting article Salty....
Seems to boil down to non linear theories that cannot be duplicated in Tank basin tests.

That makes sense.

In similar ses state tests we tried on open transom flood in solutions to recover large tenders, we found that you cannot scale 'inertia' in tank tests.

[svTOTEM]

We had a series of 3 rogue waves, sailing to Papua New Guinea - damn rough passage with 3 days of sustained 30 to 50 knots and 4 to 5 meter seas. As we approached Jomard Entrance through the Louisiade Archipelago wind dropped, so we started the engine in a race to get anchored into an atoll with good light. With eased conditions, I put a meat line in, and at looking back to check it – just about crapped myself at seeing a mountain of water.
It was more than 10 meters high, 15?, I don't know – hard to estimate because its mass was vastly bigger than anything else around, and certainly higher than mid mast height(68’). We slide up the front face – what a ride! The top 2 meters were collapsed on itself in pure white water swirling every which way. We started to peel off to the right, and I realized the rudder was stalled from no flow. I wacked the throttle to full, the rudder caught, steering returned. Sliding down the backside, knees shaking, I looked back and saw 2 more identical waves.
After they passed, Behan popped up and said something about the waves feeling a little bigger. Yeah, a little I said.
There's something to be said for keeping a good lookout.

[Pelagic]

svTOTEM
Was that still south of Jomrad Pass or inside heading towards the Conflict Group?

Have had strong currents in that area, but nothing like you described in waves.

Did have something similar once approaching China Pass from the South

[nomadic mama]

Pelagic- other half of svTOTEM here. That was still south of Jomard, not towards near Conflicts...we weren't inside yet. I suspect the rapid change in depth was a factor, since it goes from thousands of feet to a few hundred in a very short distance. It was just a few minutes after I suggested to Jamie that we should chuck out the fishing lines... oops...

[Pelagic]

Thanks...that makes sense and similar to what happened to me south of China Pass.

[Hud3]

Large waves appearing "out of nowhere" are in most cases to be expected, though infrequently, as they are produced as a part of the normal wave spectrum. In 40 knots sustained winds and unlimited fetch, you'd expect most waves to be in the "average" 12 ft range, and the larger "significant" ones to be about 20 ft. But every now and then a 40 footer would come along.

Here's a bit on the subject from NOAA...

NOAA Forecast = wave height 10 feet
• Hs = 10 ft
• H (mean) = 0.64 times Hs = 6.4 ft
• H (most probable) (slightly less that H mean) = 6 ft
• H1/10 (10% highest waves) = 1.27 times Hs = 12.7 ft
• H1/100 (1% highest waves) = 1.67 times Hs = 16.7 ft
• Hmax (highest wave you should be on the alert for) = approximately 2 times Hs = 20 ft!

Therefore, a forecast of 10-foot seas in open waters means a mariner should expect to encounter a wave spectrum with
many waves between 6 and 10 feet along with a small percentage of waves up to 16 feet and possibly even as large as
20 feet!

During the Gulf of Alaska storm on March 10, 2005, buoys observed waves heights as high as 47 feet in the
northern Gulf. In a wave spectrum with a significant wave height of 47 feet, the highest 10% of waves (H1/10) would
equal 1.27 x 47 = 60 ft. And the theoretical maximum wave height in that spectrum is 94 feet (2 times Hs)!

[mbianka]

Originally Posted by SaltyMonkey

New article on rogues:

When Good Waves Go Rogue - Issue 15: Turbulence - Nautilus

Don't look behind you!

Funny that's what my crew said to me as we sailed down Long Island Sound in gale conditions with me at the helm. Things started off OK but, as the fetch increased things got white knuckle interesting. Don't know if we experienced a rouge I was not looking. But, three miles from our destination the dingy suddenly was swamped and we nearly broached trying to go back for it. The sound was not open ocean but, closer in shape to a wave tank. If rouges can be reproduced there it seems the could happen in rectangular bodies of water like Long Island Sound too. Interesting article.

[Alan Mighty]

Back in November 2006, the cargo ship Westwood Pomona off the Oregon coast reported an estimated 70 ft (21 m) rogue wave when the significant wave height was 12 ft (4 m).

Most of the archives on the incident are now behind paywalls. For newsclips with little detail, see:

https://www.survivalmonkey.com/threa...ay-night.4728/

Rogue wave smashes into cargo ship

If the estimates of wave height were correct, that's a multiple of 5.