Dutch couple found dead, their sailboat found upturned

[olaf hart]

Steve, if your floors are going to be flooded anyway, what about filling the space with airbags?

Store them deflated along the vertical berth walls, some sort of life raft inflation system to pump them up.

Folks are always getting rid of old life rafts, maybe think up a way to reuse the tubes and gas bottles?

[DumnMad]

If this unsinkable mono is a serious consideration you need self-inflating salvage bags that burst out of exterior pockets near the water-line.

In most cases its probably better and cheaper to have a good navigator on board.

[DumnMad]

BTW Very sad about Waldy (75) and Ria Finke (69), ........From the photo I think their lives were cut way too short and a great loss.

[Mogga]

Very sad condolences to all who new them.
I had a quick skim through there web site I think it could be an aluminium boat.
I also stumbled across a picture of them which looks like them aground in very heavy surf . My Dutch is not very good so did not understand the caption. She has also
lost the mast at some time by the photos . This is complete conjecture but it may
be connected.

[arsenelupiga]

Originally Posted by Polux

Interesting article and not only this part:

In 2008, the International Sailing Federation (ISAF) set up a working party on keel losses, and they found 72 cases since 1984 of boats losing their keels.

There were defined causes in 44.5% of cases, but only three were attributed to keel bolt failure. Other causes included welded fin failures (11), grounding collision (8), internal structure (8) and canting keel system (2)....."

keel failure is similar to cat flip. And mortality rate similar i guess around 50%. Also chance numbers seem about in line with number of cat flippings.

If I had mono and be humble, this would be one to add to list of things to keep eyes on.

[Mogga]

If you look at their website there is a photo of this boat in heavy surf on a beach somewhere, and pictures of the boat being repaired from a dismasting.
I am sure the boat from the pictures on their website is aluminium.
I am not sure the two incidents are connected but indicates that at sometime the boat has
seen a lot of action,which may have caused undetected damage to the keel.
This may account for the sudden catastrophic failure,just a guess.

[Mogga]

Just another note The Samoa can be built by anyone who buys the plans from
Van de Stadt and can be made in steel aluminium or woodcore epoxy.
As we have learned not all ship yards stick rigidly to the designs which has led to problems in the past
The other thing that strikes me is that the design of the keel has a narrow root
and although many have been round the world, faulty original workmanship
or incorrect repair of damage is the most likely scenario .
Who would have thought an Oyster would have the keel drop off, but one fell off an
Oyster 82 last year. I like the Samoa47 and had a serious look at a Trintella 50 which is
similar but a longer keel.

[Pete7]

Originally Posted by Panope

Any ideas on seakeeping ability of a fully flooded/barely floating monohull (with keel attached)? Seems like it might be fairly stable as long as the water is high enough to not 'slosh'. Sorta like how a FULL water tank is safer than a sloshing one at 1/2 full. Steve

Have a look at the E Tap range of European yachts. In the past they have done demonstrations but cutting the underwater fixtures, allowing the hull to flood and then sailing back home.

If you're only short of 100 cu ft, then a set of rib tubes deflated under the bunks until needed and a diving cylinder might be the answer.

Pete

[arsenelupiga]

Originally Posted by olaf hart

Steve, if your floors are going to be flooded anyway, what about filling the space with airbags?

Store them deflated along the vertical berth walls, some sort of life raft inflation system to pump them up.

Folks are always getting rid of old life rafts, maybe think up a way to reuse the tubes and gas bottles?

i use empty plastic bottles from bottled water to fill voids where appropriate. They are also useful for plenty of other applications.

[GordMay]

“... When a boat loses a keel at sea the first reaction is often to blame the keel bolts, but the evidence does not support this; and other failures are actually more common. In 2008, the International Sailing Federation (ISAF) set up a working party on keel losses, and they found 72 cases since 1984 of boats losing their keels. There were defined causes in 44.5% of cases, but only three were attributed to keel bolt failure. Other causes included welded fin failures (11), grounding collision (8), internal structure (8) and canting keel system (2) ...”

➥ Practical Boat Owner | XS Sailing

➥ A study of a keel - The International Institute of Marine Surveying (IIMS)

[Polux]

Originally Posted by arsenelupiga

keel failure is similar to cat flip. And mortality rate similar i guess around 50%. Also chance numbers seem about in line with number of cat flippings.

If I had mono and be humble, this would be one to add to list of things to keep eyes on.

I guess you are on a mission here. Regarding those 72 refereed nonohulls that lost of keel (in 32 years) I remember many because they took place in top racing boats during major offshore races that I follow since many years ago and I can tell you that the lost of lives is hugely far to the 50% you talk about. Lost of live was a small percentage regarding the involved crews on those accidents.

To be fair the same happens regarding cat capsizes. Yes I know of some lost lives but also of a majority of people saved after the capsizes. That difference in lost lives has nothing to do with one to be less dangerous than the other but with the fact that the ones occurred on racing monohulls that took place mostly in high profile races where the location of the boats was exactly known and the rescue normally available on short notice while some of the cat capsizes happened in cruising boats in passage with not a well known position.

Regarding numbers taking out of the scenery pure racing boats, where lost of keels and capsizes are much more frequent, cruising cat capsizes are perceptually much more frequent than monohulls losing the keel.

If you noticed from that list with 72 boats that lost the keel in 32 years only two are cruiser racers and none is a pure cruiser. Sure I can add a few more cruiser racers that I know of but the list will be shorter than the list of the performance cruising cats and cruising cats that I know that have capsized and I am not talking about the last 32 years but about the last 15 years or so and only about the ones I know.

Since there are at least 20 monohulls (or more) for each cat that can give you an idea of the difference regarding the proportion of cruising cats that have capsized and mono hulls that have lost the keel regarding the total number of each boats.

And let me say that I don't consider seriously the risk of a monohull to lose the keel (if proper maintenance and adequate inspections are carried out) as I don't consider seriously the risk of a cruising catamaran to capsize even if on that case a more prudent and conservative use of sail area is needed while cruising.

Now, this do not belong here and if you want to continue this rather pointless discussion continue it on the adequate thread regarding monohulls versus multihulls where I am going to post it too.

[arsenelupiga]

no mission here. Just pointing out potential weak point I would not ignore.

I have seen some pics of new cruising monos keel attachments that were worrying.

[Polux]

[QUOTE=Snowpetrel;2090414]

Originally Posted by hpeer

...

Very interesting, if slightly sobering reading. Definantly from the list of designers and boat names all (or almost all) of the boats listed under the welded keel failure are high tech racing machines made from foam core with a narrow cord fabricated and welded keel fin, with a bulb attached.

Its actually quite scary how many cases there are, and the list of designers is pretty varied and talented. But as far as I could see, there are no steel or aluminium yachts on that list.

You can look at it on a more optimistic perspective: Of that long list of 72 failures (occurred on the last 32 years) only two regards cruiser racers, none a cruising boat and all the others are on pure racing boats.

Many of them happened on the development of the canting keel system that due to the complexity and unknown data regarding stress originated many loses due to metal fatigue.

[boatman61]

Personally my feelings are its less to do with natural keel failure and more to do with striking.. or being struck by a solid semi submerged object.. resulting in catastrophic keel failure..
Container , Submarine.. whatever.. tho' there seems evidence that where this is believed to have happened there are no reefs to hit.. so a USSO..

[leftbrainstuff]

Originally Posted by Snowpetrel

Sorry to hear that Jedi, its a big shock when something sudden like this happens to freinds.

Thanks for the info. I think its a real wake up call when something like this happens to what looks like a very well found vessel and experianced crew.

Thanks for the heads up on the construction. Steel and a welded keel shouldnt fail, but a freinds keel came of pretty cleanly on his 35 foot steel yacht when she slipped her mooring. It broke right around the HAZ area just outside the weld.

It was poorly supported without proper floors, just frames into the keel, and we think it was some kind of corten steel, which can be harder to weld. but even so it was very unexpected on such a moderate fin keel. Hopefully we will find out the cause in time so we can make yachts safer and hopefully prevent some similar occurances in the future.

I wonder if we'll ever see a failure analysis.

Several potential failure mechanisms here. We don't have any load data which would help make some predictions. Although this is not necessary if we have access to the failed sections.

Low cycle, strain based, fatigue can occur in as little as 1000 cycles. Changes of section, stress concentrations, unknown provenance parent metals with unfavourable transition temperatures can all significantly reduce the cycles to failure. Cumulative fatigue in terms of miners law can also provide some surprising insights.

I've conducted a number of failure analyses for accident investigations. I've shown how cycles to failure can be magnitudes less than assumed.

Without analysis of the fracture zone and determination of the weld and parent metal chemistry it's difficult to propose failure causes.

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