Catastrophic failure

[Guest]

[ QUOTE ]
Well I seem to recall a so called Scandinavian rock basher (HR42?) that broke up in minutes after grounding in the entrance to a drying harbour (in Scotland?).

[/ QUOTE ]
Dunno the details of that incident, but being continually pounded by breakers on a lee shore is a completely different thing to running into something hard on a one-off basis. As mentioned, in Scandinavia, hitting rocks is very common. See Chris Enstone's post about his Rival hitting a rock. They have a saying there that if you don't hit rocks then you're not trying hard enough. I hit an uncharted rock in Finland. Admittedly only doing 2.5 knots, but the result was a just a 1cm chip out of the gelcoat in the keel (a few more cm's across by the time the fractured gelcoat around it had been fully excavated and plugged with epoxy), and no other damage. If I'd been doing 5 or 6 knots, it wouldn't have been a very pleasant experience, but I'm quite sure the keel wouldn't have dropped off. Most people I spoke to there seemed to have hit rocks at one time or another.

So this idea that boats shouldn't/can't be designed to survive a heavy grounding seems a bizarre one to me.

 

[john_morris_uk]

[ QUOTE ]
...hitting rocks in Scandinavia, many of which are uncharted, is considered almost normal practise, and boats are expected to survive.

[/ QUOTE ]But even the Swedes might be expected to show a bit of seamanlike precaution and proceed extremely slowly if they are unsure of their position and uncertain as to whether they are about to hit a rock with their keel?

 

[Guest]

[ QUOTE ]
But even the Swedes might be expected to show a bit of seamanlike precaution and proceed extremely slowly if they are unsure of their position and uncertain as to whether they are about to hit a rock with their keel?

[/ QUOTE ]
Sure - though you can be sure of your position and still hit an uncharted rock. The Finnish charts contain a warning that the charts are only guaranteed accurate in the fairways... In my case, fortunately I was proceeding very slowly because the spot on the chart didn't seem very rich in soundings which made me suspicious.

But you come across plenty of cases there where the yacht was going full tilt when it hit a rock - it doesn't do bolt-on keels any good, but you don't expect to hear of them dropping off. I heard one hit a rock while it was motoring fast at some distance away - it made quite a bang. I was reading an old article in PBO where the Swedish sailor commented something to the effect 'oh when we hit a rock in Sweden we just carry on sailing to the end of the season then lift out and fill the holes with putty'. He thought the visiting UK sailor who'd hit a rock was fussing unnecessarily by lifting out for inspection...

 

[Robin]

[ QUOTE ]
So this idea that boats shouldn't/can't be designed to survive a heavy grounding seems a bizarre one to me.

[/ QUOTE ]

I think they probably ARE designed for normal incidents. We do not have a huge problem of loss of boats or life from keels falling off do we, or am I reading the wrong newspapers? I've bumped the bottom with pretty well every boat I've ever owned without doing any damage (though I did rip the centreboard case out of a Merlin Rocket doing it in a gravel pit flat out under spinnaker /forums/images/graemlins/blush.gif).

I bumped the same hard sand (at 6kts) as the Dehler mentioned in my post above and unlike it luckily had no damage to my Jeanneau although at the time I was very worried about the wash from the usual Poole cowboys that were roaring past. In fact it was the wash from one of the mobos that helped get us off and away. Thanks BTW Poole Harbour Commisioners for re-buoying the Looe Channel a few days later and sending out the notice locally just a few days too late!

Since it is confession time I also knocked a football sized hole in a Westerly 33 Ketch (read HEAVY built) by running into a large green starboard buoy at 6kts. We had just returned from a rock hopping 1000ml cruise, it was crystal clear vis, no wind, at night and the buoy had a big green flashing light on it. We were on the pilot dropping the mainsail and assumed that the tide (biggest spring of the year) was carrying us up the channel not running across it /forums/images/graemlins/blush.gif. Now that Westerly was very heavily laid up, but the damage was done above the waterline where the panels were a bit thinner than the bottom, the buoy bounced off the anchor on the bow and came back for a 2nd go knocking a hole into the anchor locker. I still have the 'hole' as a reminder, it was cut out by the excellent repairers who did an invisible mend. The point here being that this was a renowned heavy build yacht (33ft and 7.2 tonnes dry weight) that was still holed, it would have holed a 'lesser' boat too probably but hey a hole is a hole, water isn't fussy about who made the hull the hole is in!

 

[Tranona]

No, not really. The RCD is an imperfect beast. However, what it has done is force designers and builders to disclose figures about their boats that help determine its characteristics.

Take the Arcona 46 in this months YM. What a lovely boat! But not the kind of boat that most would choose. As the testers comment "This boat is huge fun to sail" "she's not a beginners boat, theres way too much power for that"

Most telling is "She has a similar ballast/displacement ratio (45%) to leading cruiser/racers and, although statistically the AVS (121) and STIX (37) might raise an eyebrow with modern weather sources on tap and a seamanlike attitude towards canvas and conditions there is no reason to hold that against her."

In other words this is a fast hairy boat that needs a big crew - and try not to get caught out in a blow! And, by the way make sure you have plenty of water because the draft is 9 ft!

One hopes that the owners appreciate the nature of the boat before they spend their £300k! The statistics help (and comparison with other boats)

Sun Odyssey 39i Arcona 46 Regina 35
Disp/L 160 142 166
SA/Disp 22 26 24
Ballast 31% 45% 37%
Max GZ 49 55 57
AVS 119 121 127

(sorry the spacing does not work, but I think the figures are clear)
This tells us that the Arcona is a very stiff boat, but when she goes it is at an angle close to the minimum for Category A.

What is also illuminating in relation to this thread is the construction method. The loads of the keel - which is a steel shell with lead ballast bolted to the bottom are taken along with the main rigging loads by a steel frame, rather than the GRP hull. This means that the hull is mainly there to give the boat shape and keep the water out! It can be relatively light which also means that it can allow a luxury fitout without compromising performance.

For the intended use this is an almost perfect boat, and undercuts the competition. Form an orderly queue (if you want this style of boat!). Just make sure that you understand its "limits".

 

[Guest]

[ QUOTE ]
think they probably ARE designed for normal incidents.

[/ QUOTE ]
Hopefully, but there seemed to be an idea being expressed that it wasn't practical or desirable to design a keel so that it can withstand major impacts. Where keels have dropped off - or nearly dropped off - there seems to be an attitude along the lines 'well the boat must have had a grounding, so what do you expect'. Which doesn't seem good enough to me. I wouldn't expect the keel to come significantly loose, even after a very hard grounding, and it seems to me that that's achievable.

Also, the 'well the boat must have had a grounding, so that explains that' attitude seems bizarrely circular logic to me where there is no particular evidence of a grounding except for the keel coming loose. It's a rather defeatist attittude IMHO.

 

[boatmike]

I would agree. Racing boats are by definition designed for maximum performance and a different catagory entirely. I would like to think also that their crews know this and have back up plans to minimise danger in the event of failure. My worry, and it's not lessened by the subsequent posts on here, is that many are not aware of the failures that have happened where a keel has indeed fallen off and the boat capsized, and think still that those who say (paraphrasing) " I hit a rock at 6 knots and suffered minimal damage" are somehow not telling the truth. There are indeed many boats built that will survive this punishment. So should the rest!
All I ask is that cruising boats, sold in many cases to unwitting buyers who trust implicitly in the "these guys sell loadsa boats so they must be good" philosophy, should be covered by legislation which says something meaningful.
The weasel words in the current standards are completely useless in this respect and absolve the builder from responsibility. Caveat Emptor indeed... BUYER BEWARE!!

 

[Aja]

This is lifted from the Scanmar Owners site, without comment:

"The Scanmar 35s were awarded the "Blue Sign" by the Swedish Maritime Authority, which is loosely analogous to the Lloyd's of London specs, and indicates a high degree of construction quality. Each boat is individually tested and must survive a hard grounding at hull speed without suffering any structural damage. If the boat survives that and other tests and meets or exceeds specifications it is awarded an individually-numbered Blue Sign."

Scanmar Owners Site

They certainly don't seem to make boats like this anymore, if they do they should be first on the list to view.

Donald

 

[Robin]

[ QUOTE ]
I would agree. Racing boats are by definition designed for maximum performance and a different catagory entirely. I would like to think also that their crews know this and have back up plans to minimise danger in the event of failure. My worry, and it's not lessened by the subsequent posts on here, is that many are not aware of the failures that have happened where a keel has indeed fallen off and the boat capsized,

[/ QUOTE ]

Boatmike, I'm not arguing for weakly built boats far from it but I do think there is a certain amount of circular paranoia here in some respects. As I recall, the Bavaria keel that was damaged was a Bavaria Match, which is a race boat even though some race more at club level and was one that was said to have had prior groundings. Hooligan was very much a race boat and I believe had additional mods to it's keel after build. Drum (many years back) was very much a race boat. The one off South Africa I don't remember except that it was a design I don't know, race or cruise?

Now scratch my little grey cells more and I cannot recall other incidents, excluding the exotics like Open 60s but that is not to say there weren't more but that I cannot recall any immediately. So many of what I do hear reported are actually the same incident regurgitated via different sources.

So a challenge!! Can you please list all of the documented keel fallings off in say the last 10 years? We can then maybe compare that with the numbers of boats afloat and miles sailed to see the real extent of any problem.

Edited PS

I could be really provocative and ask also for figures on the number of cruising multihull capsizes over the same period by way of comparison, adjusted of course to reflect the much smaller numbers of these afloat than monohulls and multis don't have the excuse of a keel falling off! Just to put things in perspective?

 

[Robin]

[ QUOTE ]
Each boat is individually tested and must survive a hard grounding at hull speed without suffering any structural damage. If the boat survives that and other tests and meets or exceeds specifications it is awarded an individually-numbered Blue Sign."


[/ QUOTE ]

WOW! But would you BUY a brand new boat that someone had just subjected to that treatment???? I wouldn't that is for sure!

 

[Guest]

[ QUOTE ]
As I recall, the Bavaria keel that was damaged was a Bavaria Match, which is a race boat even though some race more at club level and was one that was said to have had prior groundings

[/ QUOTE ]

If I remember correctly, the charter fleet of the Adriatic one that lost its keel was inspected and more than one apart from the one where the keel actually fell off was found to have keel problems. Again, if I remember correctly Bavaria tried to argue that the fleet must have suffered groundings, but there was no real evidence of this given beyond some indistinct photos which didn't seem to show any recognisable evidence of grounding.

Although those were a particular model of Bavaria, personally I'd be concerned about what it says about what the manufacturer thinks is an acceptable strength/technique of fastening.

[ QUOTE ]
Now scratch my little grey cells more and I cannot recall other incidents

[/ QUOTE ]

Other Bav ones that leap to mind are the one that lost its keel on Brambles Bank (Tout Va Bien? if I remember correctly), and reports of a new Bavaria on the Algarve about 4 years ago, ran aground at low speed in harbour, keel separated from hull. And the one mentioned in yesterday's thread "Shock, Bavaria keel stays attached".

Anyone remember any others?

 

[Aja]

Robin

That is the peculiarity. Hundreds of people have - because of the fact that they have been run into rocks at hull speed.

Hence my statement 'without comment'.

Donald

 

[Robin]

[ QUOTE ]
That is the peculiarity. Hundreds of people have - because of the fact that they have been run into rocks at hull speed.


[/ QUOTE ]


For Sale:-

Brand New Volvo V70. Each one individually crash tested by driving into a brick wall at 70mph so you know it is (or at least was) a very safe vehicle.

Would you buy it? Nowt so queer as folks! /forums/images/graemlins/smile.gif

Robin

 

[Bajansailor]

"The Scanmar 35s were awarded the "Blue Sign" by the Swedish Maritime Authority, which is loosely analogous to the Lloyd's of London specs......."

I think they mean the specifications issued by 'Lloyds Register' (which is a classification society), not 'Lloyds of London' (who deal with insurance matters).
Oh, and the two Lloyds' are not connected in any way - they just happen to share the same name.

 

[Leighb]

[ QUOTE ]

Now scratch my little grey cells more and I cannot recall other incidents, excluding the exotics like Open 60s but that is not to say there weren't more but that I cannot recall any immediately. So many of what I do hear reported are actually the same incident regurgitated via different sources.

So a challenge!! Can you please list all of the documented keel fallings off in say the last 10 years?

[/ QUOTE ]

Suggest a read of latest Yachting World (January 2008) will enlighten.

Lists 6 specific incidents since 2001, total of 13 fatalities. /forums/images/graemlins/shocked.gif
I agree most were racing designs, but not all. Includes Hooligan.

makes interesting/ alarming reading. Further to come in next edition.

Glad I have a solid long keel yacht, also main encounter is likely to be East Coast mud/sand.

 

[boatmike]

____________________________________________________________________
I could be really provocative and ask also for figures on the number of cruising multihull capsizes over the same period by way of comparison, adjusted of course to reflect the much smaller numbers of these afloat than monohulls and multis don't have the excuse of a keel falling off! Just to put things in perspective?
____________________________________________________________________

Yes you could be provocative and you have been. But I will answer your question.
1. Not all monohulls are the same, neither are multis. There are some multis I don't like either for entirely different reasons and I have owned and sailed many monohulls too.
2. I specifically said I felt knocking Baverias in isolation was wrong, and having been professionally involved with many popular builders here and abroad I deliberately avoid naming names.
3. I have, as many know, built my own Prout Snowgoose which was a choice I made primarily because she is a very safe boat. I don't collect statistics but I don't believe anyone has ever capsized one. When building her I have "designed in" extra watertight bulkheads and foam filled compartments. Both bows are heavily reinforced with kevlar.
4. The INTEGRAL keels on the snowgoose are in fact very much like the keels on a long keeled monohull apart from their aspect ratio, and the fact that they are not ballasted. In fact they form watertanks, so if one was holed the worst disaster would be limited to contamination of the fresh water supply on that side.

As this thread is about keels, and building boats to withstand collisions at hull speed therefore I can tell you that mine is designed and built to do so, so this particular physician has indeed healed himself rather than make excuses that it doesn't matter. It does.

 

[Sailfree]

You really need to think through your arguement

eg Grounding - hit a rock or sand or silt?

What sea state calm or a gale with 3m waves or higher causing the boat to pound

Taken to its extreme and using the car analogy you are asking for all cars to be banned and only tanks allowed on the road so that they suffer no damage when they hit walls or barriers.

If I was to go pacific I think I would buy a steel boat due to the coral risk and accept it was slower. Crossing Oceans I would want an AVS in excess of 130 & preferably 140deg + but please don't inflict these boats on me for weekend sailing in the Solent or a X channel dash.

Your argument is a stupid as stating that all sailing boats should stay upright when hit with strong winds which immediately raises the question of how strong a wind.

The facts are that a couple of boats including the Bavaria match have IMHO inadequate keel /hull joint strength/design and regrettaby 2 lives have been lost but as a structural engineer I am part of a profession where construction mistakes/errors kill hundreds every year and while I regret every death it is unfortunately not possible to design everything for every occassion so that no one is ever at risk.

 

[wotayottie]

[ QUOTE ]

Now scratch my little grey cells more and I cannot recall other incidents, excluding the exotics like Open 60s but that is not to say there weren't more but that I cannot recall any immediately. So many of what I do hear reported are actually the same incident regurgitated via different sources.

So a challenge!! Can you please list all of the documented keel fallings off in say the last 10 years? We can then maybe compare that with the numbers of boats afloat and miles sailed to see the real extent of any problem.


[/ QUOTE ]

Well we have had two at our club alone in the last 10 years. One Westerley, a 33 I think, which lost a bilge keel and sank on its mooring after an earlier grounding. The second was another British make who's name escapes me for the minute. Same thing.

Mind you, I've also seen in the last ten years three examples of long keel old trad boats with sever damage after groundings - in one case involving a lot of pumping and a full tilt motor into the arms of the boat lift at Swansea.

[ QUOTE ]


I could be really provocative and ask also for figures on the number of cruising multihull capsizes over the same period by way of comparison, adjusted of course to reflect the much smaller numbers of these afloat than monohulls and multis don't have the excuse of a keel falling off! Just to put things in perspective?

[/ QUOTE ]

I think you'll struggle on this one. Cat capsize on cruising size vessels is largely a leftover reputation from the very early days and old boats like the Apache. Its way harder to turn over a modern cat than a modern mono of the same length. If you doubt it, look at the area under the stability curves to see the energy involved.

 

[boatmike]

Thank you for that.
Firstly I believe I have thought through my argument very well. I can even spell "argument". It seems you don't agree with it and you are entitled to your opinion but don't drag what is an otherwise well mannered thread down to the level of calling other people stupid. I will listen to any well structured argument but not abuse.
Interestingly I am also a chartered mechanical engineer, and have specialised in composite structures so claim to know a little about these things. Having been intimately involved in yacht design rather than building bridges or tower blocks I think you make several sweeping assumptions. A steel boat is not necessarily the answer and in fact a well designed composite vessel can be as good if not better than a welded steel structure in many respects, especially strength to weight ratio. I would agree however that comparing steel vessels with lightly built series production boats like those we are discussing usually leaves no contest. I also believe you are correct to point out that a blue water cruiser is different from a Solent ditch crawler. However, the point here is that if we take the majority of lightly built cruisers that are aimed at the cross channel holiday and Solent sailing it is my contention that they should be able to withstand a collision with a rock at hull speed in reasonable weather. By reasonable I would suggest in winds of up to F6-7 and associated sea states. Above this most run for marinas anyway. Open ocean conditions and grounding on coral in hurricane conditions is not expected. The precise definition of what you expect a boat to withstand is obviously open to debate. What is not open to debate is that some vessels are patently not designed to withstand a hard grounding of any sort in relatively calm conditions, lets say a F4-5 in the Solent. In my opinion this should be a minimum design requirement and builders saying "of course you broke it, you grounded it" is indefensible.

 

[Sailfree]

Thanks for the correction on arguement I have smacked both my one typing finger and brain as they are obviously not co-ordinating to well at present. However I would point out that I always prefer to read informative and even contraversial posts with typos and smelling misteaks than dissuade someone from posting due to incorrect spelling/syntax or grammar

If I called you stupid I am sorry but I believe I was comparing your argument to something else and stating by comparison that these arguements are both stupid as its impossible to define a limit/set of conditions that something should withstand. No offense was intended but like many quickly written pieces the arguments could be better or more sensitively made given more time.

You do make a good point about the strength weight of composite materials and I think market forces would endorse your view if it was economical.

We are all guilty of having our own hobby horses - my own is AVS. On a priority basis I would prefer more boats to have an AVS in excess of 130deg than a stronger keel. I wonder which aspect would contribute to saving more lives?

Sometimes it is necessary to bring in legislation to improve standards over a whole industry but with boat manufacture there are all standards present. Its more the case of which ones people consider necessary to pay for and the vast majority are happy with the standards that Bavaria build their boats to - thats why they sell.

I respectfully suggest you consider who would be prepared to pay the extra for a boat built to withstand the impact you suggest and if you say we should all be compelled by law then really you are saying that you are so right in your view that it should be legally imposed on others and their free choice taken away.