Loss of KELAERIN Rescue of Crew June 2018

[a64pilot]

Interesting, because of all those listed materials, cast has the lowest modulus of elasticity ( if I use the term correctly) Extruded is similar to forged steel in that it has been worked, and the good thing about Extruded is that it will deform and distort, badly before failure.
Cast on the other hand breaks.
From my background, designing to have something shed loads by distorting is better than a sudden failure.


I still want to see the failure mode of this hatch, that would be interesting and informative.
Speculation is interesting, but post accident analysis is where you learn something

[Eight Sails]

Originally Posted by bcoletti

Great post - thank you. Can you expand on the cat v mono point. With the same fact set what would be the most likely outcome if Kelaerin had been a similarly sized cruising cat?

What's the difference between a cat and Kelaerin? It's been said, not entirely in jest, that the biggest difference between a monohull and a multihull is that a monohull's point of greatest stability is resting on the bottom and a multihull's greatest stability is floating upside down. More seriously, it's been written that "A multihull is the best survival platform and should be left only when rescue is absolutely assured" (Multihull Tactics in Heavy Weather, Adlard Coles' Heavy Weather Sailing, 30th Anniversary Edition, McGraw Hill, p. 154). That would be a good place to look for other answers.

The liferaft question is interesting and the Great Lakes Singledhanded Society's required equipment list (http://docs.solosailors.org/pdfs/Std...uiredEquip.pdf) sheds some light on it:

6. A selfinflating life raft designed solely for emergency use which has been inspected, tested, and certified by an approved servicing agent within 40 months prior to the Challenge date. The inspection certificate must be presented prior to the Challenge. The life raft must be stowed so as to
be readily accessible to the helmsman in an emergency. A selfinflating life raft is highly recommend, however a skipper may substitute a survival suit that provides appropriate thermal protection and floatation for the requirement of a life raft provided that a Personal Locator Beacon with built in GPS positioning, 406 MHz signal, and 121.5 MHz homing capability, SPOT or the equivalent is also carried.
7. Multihulled yachts may substitute a survival suit meeting the minimum thermal protection and floatation capabilities of the Mustang MS 2175/6 "AntiExposure Coverall and Work suit" for the requirement of a life raft. The Survival Suit is to be stored to be accessible when boat inverted.
.
.
.
Additional multihull requirements:
1. A through hull “crash box” compartment or, as an alternative, a watertight container attached to the boat, external to the hull. Either choice to be accessible at all times, including when the boat is inverted, containing:

a) Handheld radio
b) All flares
c) Cutting tools
d) GPS EPIRB

[Eight Sails]

Originally Posted by a64pilot

Interesting, because of all those listed materials, cast has the lowest modulus of elasticity ( if I use the term correctly) Extruded is similar to forged steel in that it has been worked, and the good thing about Extruded is that it will deform and distort, badly before failure.
Cast on the other hand breaks. From my background, designing to have something shed loads by distorting is better than a sudden failure.

Good points. No construction is ideal. Castings can also have stress risers that concentrate stresses around angles and cast detail like wedges or tabs for hatch dogs. Over time, cracks could occur.

This again moves away from the hatch builder's responsibility to the boat builder's. Deck areas in the way of openings large and small need to be well reinforced (in GRP construction, solid glass not core), not only to hold fastenings and resist moisture penetration but also to provide a solid platform for the attached hardware. As flexible as the hull and deck may be overall, the area around a hatch shouldn't be as flexible. Raised base moldings and dams will help, as will a generous margin of solid material surrounding the hatch.

Sadly, this also reverts to the point that the standards bar is set pretty low in multiple categories of boat structure and hardware. (As an example of the former, consider the well-publicized breakage a fin keel at the root, with loss of life, on a popular, name-brand racer/cruiser that presumably met standards). As in so many things, a hatch opening accident would be more likely to result from a chain of smaller deficiencies or incidents than from a single, glaring fault.

That being said, my choice would be a cast hatch set in a solid deck. One of the things I like about my old AH hatches is that the rimless acrylic lens is recessed into the cast base, with no horizontal exposure to water sweeping the deck -- effectively, an integral dam. It also made replacing the lenses myself dead easy and facilitated making plywood blanks to fill the openings while I waited for the new lenses. What's easy gets done. I tossed those out after the project. Maybe I should have stowed them instead, for emergency use.

[cyan]

Originally Posted by a64pilot

Realize of course that "dams" are the responsibility of the boat manufacturer, not the hatch.
If you want them, they ought not be hard at all to add, even out of aluminum.
I'd be sure to have a drain in them though, at least two, but probably four, 1 near each corner

Good advice.
It looks like the forward hatch on Kelaerin had a wooden riser but not a dam, with the opening direction and dogs pointed forward. (common in the tropics) ...

[hellosailor]

"the opening direction and dogs pointed forward. (common in the tropics) ..."
Also long time expressly not allowed under some offshore racing rules, including the Bermuda races, last I recall. Because of the "water ingestion" hazard.
The physics of it all, including things like water pressure holding hatches down, the potential force of a column of water from a 20' or 40' breaking wave dropping onto a hatch or deck or dorade...the pressure developed as a hull is "squeezed" to produce pressure popping things out...I know I've actually read about these numbers in books over the past 40-odd years, and neither the hazards nor the numbers have changed. We do *know* now that rogue waves are real, and about 1000x more common than previously suspected, but other than that I don't think there's been anything new about offshore safety. Other than perhaps having the incredible blessing of weather forecasts for seven days out in much of the world (certainly in the Atlantic) versus the old 24-hour HF reports from ships at sea. Pretty much three days of weathercasting everywhere now, even if the weatherman is still often the "NOAA-nothing Man" even on the well forecast east coast of the US.
With experience comes complacency, and increased danger. Not just in sailing.

[sagablu]

Originally Posted by Uncle Bob

Hey, you learn something every day. Eleven Springfields you say, I believe, I believe But none of them have a nuclear powerplant, however the entire country appears to be "managed " by Homer and friends.

Managed by Homer, No! That is insulting. Mr. Burns, now that is more likely.

[hellosailor]

Here's a quiet little way to make plastic dogs fail: Lubricate them.

Many common plastics are attacked by pertrochemicals, so shooting a little WD-40 on the shafts to clean and lube them, over a decade or so, would help ensure that they cracked and failed. The same way that putting any petrochemical-based cleaner, wax, or polish on plastic port glazing will help ensure that it goes foggy and crazes over the years.

Are your hatch dogs cast from an engineered resin? Or maybe something cheaper and simpler? Did the maker test them for internal air bubbles or stress flaws? Does anyone even think about these things while shopping for hatches? Or, questioning the hatches on their built-to-a-price boat? (What, the keel falling off an Oyster?!)

The flip side of, as Robert Heinlein said, "Any sufficiently advanced technology will be indistinguishable from magic."

[Snowpetrel]

Originally Posted by a64pilot

Interesting, because of all those listed materials, cast has the lowest modulus of elasticity ( if I use the term correctly) Extruded is similar to forged steel in that it has been worked, and the good thing about Extruded is that it will deform and distort, badly before failure.
Cast on the other hand breaks.
From my background, designing to have something shed loads by distorting is better than a sudden failure.


I still want to see the failure mode of this hatch, that would be interesting and informative.
Speculation is interesting, but post accident analysis is where you learn something

The cast hatches normally have much thicker components. This more than makes up for any weakness of the cast material. But I dont think the failure mode is typically due to the frame. Either the perpex cracks, pops out or the dogs let go.

[a64pilot]

I guess I’ll keep asking.
Is there no one near Ft Bragg Calif who can go look and maybe take pictures?

[a64pilot]

Originally Posted by Snowpetrel

The cast hatches normally have much thicker components. This more than makes up for any weakness of the cast material. But I dont think the failure mode is typically due to the frame. Either the perpex cracks, pops out or the dogs let go.

I understand, and honestly did then too, just however I don’t like blanket statements, like X is better than Y, cause that is not always true.
The answer as always when you drill down into anything, is it depends.

What really picked my ears up was when I read that Magnesium handles and dogs were superior.
I can tell you from one of my last jobs, Magnesium and salt water do not mix, I would not have magnesium of any form on my boat, stuff is wonderfully strong and light, and corrodes from you looking at it.

[Jim Cate]

Originally Posted by cyan

Good advice.
It looks like the forward hatch on Kelaerin had a wooden riser but not a dam, with the opening direction and dogs pointed forward. (common in the tropics) ...

Owww! That riser not only isn't a dam, but increases the exposure of the gap twixt lip and deck and raises it up into a more risky place... and moves it further from the strength of the deck and with longer fasteners. And they may not even be through bolted (speculation)!

Bad design IMO.

Jim

[a64pilot]

Originally Posted by Jim Cate

Bad design IMO.



Jim

I keep thinking that once someone gets a good look and maybe pictures, there will be an Aha moment.
Although something completely unexpected may be found.

It looks as if that hatch was added after manufacture, not by the builder?

[Pelagic]

Originally Posted by Eight Sails

What's the difference between a cat and Kelaerin? It's been said, not entirely in jest, that the biggest difference between a monohull and a multihull is that a monohull's point of greatest stability is resting on the bottom and a multihull's greatest stability is floating upside down.

I think that is a bit too simple of a comparison.

For a mono to sink, it requires a major breach in the hull that cannot be plugged due to major stuctual damage.

If both types were running downwind and breached or pitchpoled, a hatch torn off and crew injured .....

the Mono would have righted and recovery could begin, while the multi remains upside down.

Which boat would you rather be in?

I am quite sure if Kelaerin had been damaged outside rescue range, those two experienced sailors would have safely reached port...as the yacht did after abandoned.

Keeping the water out after damage is relatively simple if structurally the hull/deck is not broken.

Whereas righting an upside down Cat, is impossible and rescue is your ONLY option.

[cyan]

Originally Posted by Jim Cate

Owww! That riser not only isn't a dam, but increases the exposure of the gap twixt lip and deck and raises it up into a more risky place...

While beating this hatch-discussion to death, I think it gets worse...
An interesting detail of the larger Lewmar Ocean hatches is that the opening edge of the aluminum lid frame has a rectangular "bent-outward" section that is about 6" long, allowing fingers to slide underneath when opening from the outside. (image is smaller than a 70) If you were to mount this intentionally-bent-outward lid segment (opening side) facing forward at the edge of a wooden pedestal, you might just might be pointing a small "water scoop" directly toward the angry seas.

The Kelaerin pics actually show two forward-facing hatches on the fore deck, with the dinghy apparently lashed on top of the most forward hatch before the incident.

I agree with a64pilot that additional pics would be quite helpful for the rest of us, though maybe not what the owners want right now?
If so, my apologies...

[Snowpetrel]

^^ I think you might be onto something Cyan. The 4th photo shows the dinghy stowed just in front of the hatch. Would it be possible that the dinghies transom somehow caught on hatch lifting handle and then ripped it open?