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Old 10-07-2018, 19:03   #316
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Re: Loss of KELAERIN Rescue of Crew June 2018

Regarding "where does the energy come from" it is likely sudden large waves that pop up out of no where are the result of multiple waves from different sources/directions combining with one another. Waves from different directions can create sudden lulls and peaks that do not follow the normal wave train sequence. The energy doesn't have to be a any more to get a really big wave above the average height. A solitary big wave can be the instantaneous peak of multiple small waves all combining at the same time and place. The various waves can additively combine into a large height or subtractively combine to reduce wave height. This leads to bigger variations in wave height than if the waves were all part of the same sequence.

Another factor is that waves don't give up a lot of energy as they cross one another. Since water is incompressible the energy just flows along with very little to dissipate the energy. Therefore, there can be a massive amount of energy stored in ocean waves.
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Old 10-07-2018, 19:28   #317
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Re: Loss of KELAERIN Rescue of Crew June 2018

I once saw a very weird set of standing waves, about 50 miles east of the top end of flinders island, near the shelf but outside it in 1000 meters of water. A glassy calm day, maybe a 1 meter swell.

All of a sudden it looked like we were in a set of overfalls, the waves started standing up and nearly breaking in a very confused way. Best we could tell on the GPS there was no current. It covered maybe 200 meters then went back to normal. All we could think of was a localised upwelling. But there was no change in seacolor or birds working like normal wgeb you have big upwellings. I have it on video somewhere.. Very odd, And I was glad it wasn't a nasty day! Click image for larger version

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Old 10-07-2018, 19:35   #318
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Re: Loss of KELAERIN Rescue of Crew June 2018

https://uwaterloo.ca/applied-mathema...ave-animations

Some interesting stuff on internal waves here.
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Old 10-07-2018, 19:49   #319
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Re: Loss of KELAERIN Rescue of Crew June 2018

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Originally Posted by gatorman49 View Post
Just read ADRIFT. Interesting story, speaking of the Pacific. Good read, can do it in a day.



I read adrift many tears ago, but I thought it was set in the Atlantic.


edit: Ignore my post. Should have googled first. There appears to be a second book with the same name. I was thinking of Steve Callahan from 1982.
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Old 11-07-2018, 16:16   #320
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Re: Loss of KELAERIN Rescue of Crew June 2018

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There's also Atkins & Hoyle, still making fine hatches after all these years, but don't market aggressively and aren't a big player in today's production yacht or aftermarket chandlery business. They make new hatches and davits and also have an OEM spares and hatch reconditioning service, with support for every hatch they've ever made. OEM on both of my Contessas (26 and 32). Pretty bombproof stuff. I got replacement lenses for all my deck hatches from them several years ago.
My 33’er has AH hatches and lights. I love em. Great kit.

Wish the big boat had them.
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Old 11-07-2018, 16:34   #321
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Re: Loss of KELAERIN Rescue of Crew June 2018

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The problem is that"basic physics" does not account for nonlinear effects, and it took quantum mechanics to explain some of the odd wave behavior, by people like Al Osborne. The BBC has some good programs on this stuff, now around 15 years old:
https://www.dailymotion.com/video/x225ztn

I remember reaching in a 35 ft mono, confused seas of maybe 3 meters, 15 knots of wind. This was only 10 miles offshore in southern California, and the dominant pattern was a "hurricane swell" from the Southwest that the local surfers were eating up. In addition, I think there was the normal train from the West (travelling with the onshore breeze), but smaller.

We would go minutes of crossing the dominant swells, then a few seconds of weird, almost violent yawing, then then back to the rhythm. Every once in a while off either side you could see a weird peak come out of nowhere and reach for the sky at maybe 4 meters (sometimes higher), then dissipate. We were slapped a couple of times by such "peaks", but no damage- just a wet surprise.

I would hate to see a monster version of one of these weird peaks. Worse yet, to meet one in the dark. My crew mate referred to this not as confused seas, but STUPID seas. I later saw a simulation for visual effects in movies and video games that looked oddly similar...
(at 0:52)
That “confused sea” stuff, I’ve seen that. About 4’-5’ significant wave height. Crossing from Cape Bonavista to Cape Freels. There were at least 3 wave patterns. NO WIND. Cold fog and rain. My AP broke. Ran into Lumsden in dark with radar. Solo. That day sucked.
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Old 12-07-2018, 02:48   #322
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Re: Loss of KELAERIN Rescue of Crew June 2018

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^^ There is also some interplay between the surface waves and the Internal waves along the thermoclines. This may be a source of weird wave patterns. I suspect this is the real source of the change in wave patterns near the shelf.
The first time I swam through a thermocline I was shocked firstly by the difference in temperature (perhaps 6-7'c) even wearing a thick 7mm wetsuit and secondly how thin the boundary layer was. Just a matter of inches of mixed water before descending into the much colder water below.
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Old 12-07-2018, 03:33   #323
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Re: Loss of KELAERIN Rescue of Crew June 2018

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What exactly did you call it, DumnMad?...
Like your vid there were millions of wave peaks - as an engineer you would call them "one end of a normal distribution."
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Old 12-07-2018, 05:28   #324
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Re: Loss of KELAERIN Rescue of Crew June 2018

https://vimeo.com/135936542?ref=em-share

Ocean vorticity. Interesting the way the current eddies.
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Old 12-07-2018, 08:47   #325
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Loss of KELAERIN Rescue of Crew June 2018

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Like your vid there were millions of wave peaks - as an engineer you would call them "one end of a normal distribution."
Sounds accurate- beyond 6-sigma probably... but sailors get a little colorful with language. I think “prairie dogging” was stolen from National Lampoon’s “Vacation” with Chevy Chase. The term seemed to fit, as “prairie dogging seas” describes very bad things popping up. (That can cause your boat to be pooped)
Whatever it’s called, it goes a step beyond “confused seas”, and I hope I don’t ever feel the need to describe the phenomenon from the deck of a small boat again.
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Old 13-07-2018, 07:15   #326
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Re: Loss of KELAERIN Rescue of Crew June 2018

If anyone is remotely likely to be faced with this situation please consider that vessels are designed to take heavy weather on the bow and not the stern. Every text that I am aware of from "Heavy Weather Sailing" to the United States Power Squadrons sailing courses suggests using a drogue as mentioned above. Attempting to sail, even if bare poles, down wind in heavy seas is very dangerous! It sounds like the boat broached and rolled. Even worse, it is possible to pitch-pole and surviving that is problematic. I assisted with installing electronics aboard a boat in the first BOC Around Alone Race. In the southern ocean some rolled, some lost their keel and at least one pitch-poled. Please be prepared!
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Old 13-07-2018, 14:29   #327
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Re: Loss of KELAERIN Rescue of Crew June 2018

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If anyone is remotely likely to be faced with this situation please consider that vessels are designed to take heavy weather on the bow and not the stern. Every text that I am aware of from "Heavy Weather Sailing" to the United States Power Squadrons sailing courses suggests using a drogue as mentioned above. Attempting to sail, even if bare poles, down wind in heavy seas is very dangerous! It sounds like the boat broached and rolled. Even worse, it is possible to pitch-pole and surviving that is problematic. I assisted with installing electronics aboard a boat in the first BOC Around Alone Race. In the southern ocean some rolled, some lost their keel and at least one pitch-poled. Please be prepared!
Mine's designed to take heavy weather from either end.
It has more bouyancy at the stern, a centre cockpit and rigged to suit.
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Old 13-07-2018, 16:25   #328
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Re: Loss of KELAERIN Rescue of Crew June 2018

One thing I have learnt from this thread is the number of experianced sailors who strongly believe heaving too is safer than running off under bare poles. I might have to revisit heaving too, though the couple of times I have tried in in bad weather, it didn't really fill me with any confidence, and in the bigger waves the boat always seemed to end up near enough to beam on that practically it seemed much like lying a hull with a bit of steadying sail to stop the rolling.

I have heard talk about being able to hold the bow up to somewhere like 30-60 degree's off the wind when hove too. But my experience was more like 60-90 degrees on a fin keeler with big roller furler forward, and just a deep reefed main set. Prehaps a trysail would have helped, but I doubt it. In bigger seas the shear size of the wave face will always overpower any sail effect especially when in the disturbed air in the troughs, on the wave crests the boat would pivot around nicely into the wind and feel overpowered, but you really want her to do that in the trough's.

I guess this is why the Pardys started using a small sea anchor on a bridal to prevent the bow from falling off in bigger seas. This seems like a very good way to ride out a blow, but it does rely on a fair bit of highly loaded gear.

For me forereaching has always been my goto when I want to make ground that way, (or don't want to loose to much ground to leeward). It gets pretty uncomfortable, and is hard on the boat and crew, but to me I feel less of a sitting duck than if I was hove too.

One blow I am thinking off was on a delivery from Nelson to Hobart in winter on a well set up S&S 34. We had a small mid tasman low come through south of us so we slugged it out forereaching as long as we could, under 3 reefed main and storm staysail. In the end as the wind rose to about 35-40 knots from the westsouthwest this just got too brutal, launching of the tops of the crests, and landing with a solid crash. We were overpowered on the crests anyway, so I dropped the storm staysail thinking to heave to under just the main but she just wouldn't hold her head up properly no matter what I did with the sheet or tiller. The seas, though big did not seem dangerous, so we stayed like this for 8 hours or so until the wind backed to south and started easing. This kind of put me off heaving too. In retrospect I would have been better off to have dropped the main and continued forereaching under the just the storm staysail. Had it got any worse or if the seas had started breaking I would have run off but I didn't want to loose any hard won westing.

I suspect the rules change a fair bit with bigger boats, sails stay up in clear air longer, and the extra stability means you can carry more sail, for longer, so maybe heaving too works in a much higher wind range hence Skip Novaks endorsement.

Unlike a lot of people (it seems) I have no real issue running off under bare poles (or as I normally do with a tiny scrap of headsail strapped in tight) as long as the boat seems to be steering well. I've done it many times without any issues or broaching problems. It's always seemed comfortable and safe, and it makes it very easy to deploy a drogue if it gets worse. But I may have to go back and give heaving too another try.

I guess "heave to vs run off?" is in the same league as "what anchor is best?". One thing I try not to do is get too dogmatic about any storm tactic. The most experianced sailor I know survived a very serious storm deep south lying ahull. He had tried running off, heaving too, warps. In the end she lay safely beam on effectively hove to by just the windage of her masts. Not textbook but in this instance it worked for him when nothing else would.
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Old 13-07-2018, 17:17   #329
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Re: Loss of KELAERIN Rescue of Crew June 2018

https://youtu.be/AT6i_Ta3hAk

We had similar to this, with 35-40kn on the (uncalibrated) windspeed indicater, and a bigger underlying swell. Note the angle on the apparent wind gauge around 1:05. Near enough 85 deg apparent. Maybe more main needs to be set. This is pretty typical in my experience. Any tips?
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Old 13-07-2018, 17:54   #330
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Re: Loss of KELAERIN Rescue of Crew June 2018

Good posts Snowpetrel and the key message from them is to NOT be dogmatic.

Keep your options open as boat/crew/conditions guide your instincts.

But one key rider in this, is a deteriorating situation and Darkness.
Crew safety comes first, so if near the point where an abnormal set can wash the deck with solid water....at night, get them below.

I have always made the decision by early afternoon, set up either hove to or Ahull and monitored behavior in daylight.

On every boat I always check her natural windage tendencies in moderate conditions with rudder mostly turning her to windward.

If windage is too far forward then I would know that I need to remove the furled head sail for Storm prep.

I would also test a warp tied to windward stern cleat to help rudder pull her head to waves and wind.

Each skipper knows his boat's behavior the best, but often have not experienced a real survival sea state, that overwhelms them at night.

My advice:
Prepare during daylight for the worst and monitor a passive solution.

Get the crew safely down below for the night and broadcast your position.

Have faith in your boat and the hard work you have put in to maintain and prepare her.... This is when she pays you back!
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