Ok, a dumb question from a rusty once and future sailor. I was researching boats and this issue may have arisen from the Kraken yachts web site. Not entirely sure because I went down a real rabbit hole. Anyway, X manufacturer stated that its vessel can recover from 130-degree knockdown. That sounds pretty good. But does that mean/imply that such a craft would allegedly self recover from turning turtle? Without luck/wave action? Can see why a builder might not want to address a capsize directly but this inquiring mind wants to know!
Self-righting keel question
- Thread starter Mossy Dell
- Start date
The short answer to your question is no, if the vessel has a 131° knockdown it will capsize. Boats can be designed to be self-righting. The Coast Guard has a bunch of surf boats that can do just that.
Hull stability is a complex and sometimes controversial area of naval engineering. There are a number of factors that come in to play, including cross-sectional hull shape, weight distribution, deck and deck house shapes, keel shape, ballast, longitudinal hull form, the list goes on. To get an idea of the complexity take a look at the Stability Document for Bayesian, the megayacht that just sank.
A self-righting boat needs to be unstable when upside down. A catamaran is just as stable or perhaps more stable upside down than right side up because of the large expanse of relatively flat deck. That's why Cats have escape hatches on the hulls that are accessible when the cat is upside down.
Roger Long has written a series of articles on the Pride of Baltimore sinking and the boat's stability. If you are interested in learning more the series of articles are a good introduction to the topic and the controversies that arise.
loosecannon.substack.com
loosecannon.substack.com
Hull stability is a complex and sometimes controversial area of naval engineering. There are a number of factors that come in to play, including cross-sectional hull shape, weight distribution, deck and deck house shapes, keel shape, ballast, longitudinal hull form, the list goes on. To get an idea of the complexity take a look at the Stability Document for Bayesian, the megayacht that just sank.
A self-righting boat needs to be unstable when upside down. A catamaran is just as stable or perhaps more stable upside down than right side up because of the large expanse of relatively flat deck. That's why Cats have escape hatches on the hulls that are accessible when the cat is upside down.
Roger Long has written a series of articles on the Pride of Baltimore sinking and the boat's stability. If you are interested in learning more the series of articles are a good introduction to the topic and the controversies that arise.
Exclusive: Loose Cannon Obtains Official Bayesian Stability Document
'Notes to Master' Reproduced Here Without Comment
Pride & Stability, Part 1: About That 'Microburst' Theory of Sinking...
Disaster Did Not Require Extreme Winds To Happen, Naval Architect Roger Long Says
dlochner, thanks so much. Especially since I have been obsessed with the Bayesian disaster. And also have gone back into Fastnet '78 and especially the plight of Grimalkin, another yacht by the same designer. In the Fastnet, that boat endured constant capsizes and pitchpoles. I guess like many racing yachts of the time, it would only self right by wave action.
To refine my question, I did not mean to ask if a boat with a 130-degree self-righting ability, or any sailing vessel, could not capsize. Only to ask if such ability implies such a boat would self right from a capsize? Or if that's a separate technical issue?
To refine my question, I did not mean to ask if a boat with a 130-degree self-righting ability, or any sailing vessel, could not capsize. Only to ask if such ability implies such a boat would self right from a capsize? Or if that's a separate technical issue?
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 21,702
Let's first discuss a knockdown.
It occurs when the mast moves through a 90º arc and touches the water. At this point, the boat is lying on its side. For most boats, this is when water starts to flood (enter) the cabin. Water in the cabin changes the stability of the hull. It begins to sink. The sail and air in the mast would cause some delay to the mast sinking further. If the sail and the mast go under the surface, this is when the boat could head towards that 130º knockdown. Unless the boat is watertight, there may not be enough buoyancy to return the vessel upright. The sails would add resistance to the vessel's recovery. Demasted and free from rigging or sails, the hull may be able to right itself.
Luck and wave action might help or hurt a terrible condition.
Small centerboard boats with flotation space can usually be recovered even if they turtle. Crew standing on the edge of the hull, pulling on the centerboard, and even diving under the boat to release the main sheet can bring the boat back upright and get it back sailing.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 21,702
Remembering the Fastnet race, several boats were abandoned by their crew, and later, the boat was found floating on the ocean. One of the post-event reviews talks about the recommendation to stay on the boat until the boat is about to sink beneath your feet and you must step up into a life raft.
Read the true story "Once Is Enough" by Miles Smeeton (Author). He tells the story of trying to return to Britain from Australia with his wife and their sailboat. It is a great story of survival.
Read the true story "Once Is Enough" by Miles Smeeton (Author). He tells the story of trying to return to Britain from Australia with his wife and their sailboat. It is a great story of survival.
First the disclaimer, I am not a Naval Architect or engineer, however, I am working on a large schooner that will be USCG inspected and stability is a big part of the inspection process. For that I rely on my NAs.
I would not extrapolate from the builder's claim to self right from 130°, I would take them at their word. However, given this is a marketing statement, you would be safe to assume this is the best case scenario. The Bayesian stability discussions by NAs revealed the vessel's stability varied under different conditions and different sail and centerboard configurations.
The stability calculations generate a series of graphs that visually show the stability limits and also the "tenderness" of the vessel. As the Roger Long articles discuss there can be some disagreement on exactly how to make those calculations. If you are considering purchasing a boat and are concerned about its stability and ability to recover from a capsize, then it might pay to hire a NA to review the calculations and provide advice.
I don't know the source of this quote, however, it is bad advice according to a decorated USCG rescue swimmer. See the article linked below.
'Always Step UP Into the Liferaft' Is Terrible Advice, Coast Guard Expert Says
'Ridiculous Old Maxim' Raised Again Recently After 'Jambo' Sinking
Having just read about the Fastnet '79 and watched a 1.5-hour documentary and the Waterline Stories vid, from somewhere I got that this maxim was exactly what the skipper of Grimalkin and his said they had already decided. Don't get on the raft till you have to step up from the boat! I gather the reason was that abandoned vessels had been found drifting while rafts were sometimes empty or with tortured occupants. However, after the Grimalkin's skipper was washed out to sea and two crew appeared to have died as well in the cockpit from drowning or hypothermia, the son entered the life raft after the other two crew.I don't know the source of this quote, however, it is bad advice according to a decorated USCG rescue swimmer. See the article linked below.
'Always Step UP Into the Liferaft' Is Terrible Advice, Coast Guard Expert Says
'Ridiculous Old Maxim' Raised Again Recently After 'Jambo' Sinking
Very interesting I read that no vessels that hove-to in the Fastnet '79 were damaged or their crews hurt whereas 15 sailors died and 138 had to be rescued. Probably more to the story but I wonder if stopping didn't occur to many of the racing skippers. As bad as the gale got, maybe some were among those to hove-to.
What???? Stopping during a race? Heresy!
Fastnet happened 45 years ago, a lot has changed and the advice should also change. The discussion at the end of the article is worth reading. Steve D'Antonio suggests the advice is more metaphorical than literal and each case is different. On a boat that is not in imminent danger of sinking it probably better to stay aboard as the boat is easier to spot than a life raft. On the other hand, a dismasted boat with the mast banging against the hull, may not be sinking but could easily be holed and sink quickly. If that were to happen at night it would be exceptionally difficult to get into a life raft.
Unfortunately too many people can not tell the difference between metaphorical advice and literal advice. In many cases it doesn't matter, when safety is paramount there is no room for error in interpretation. While humor can serve many beneficial purposes, it can also be dismissive and, in this case, promote a life threatening bravado.
I'm not a subscriber, can't read the article, have to download crap to get free access - not happening.I don't know the source of this quote, however, it is bad advice according to a decorated USCG rescue swimmer. See the article linked below.
'Always Step UP Into the Liferaft' Is Terrible Advice, Coast Guard Expert Says
'Ridiculous Old Maxim' Raised Again Recently After 'Jambo' Sinking
The source of the quote comes from the analysis of the Fastnet disaster. It may be a paraphrase from the conclusions, it's now too long ago I read it and the original book is buried at the moment so I can't pull it out and look it up.
Hahaha – for sure this could be part of the problem...
Can't agree more! That's how we progress and improve. But at the same time, we should not forget the lessons learned, but rather build on them. A case in point are the changes to how jack lines should be run and the change from staying attached to the boat and staying within the lifelines. But these changes build on what was known and make adaptions to that knowledge to improve.
But those improvements are best done with open conversation – not with one party “hiding it” behind some kind of access limitation. So I would suggest that you quote the parts of that article you are relying on such that it is not a one sided conversation.
I have always taken the advice of “step up into the life-raft” as metaphorical – that each case is different. Hence from what it appears you are presenting, nothing has changed.
It is not only easier to spot, it is a much safer place to be. It contains all your supplies, food, etc. that gives you much greater abilities to “carry on”. Anyone that has been in a major storm at sea, and has seriously looked at what it would be to have to get into a life-raft in those conditions, would not be welcoming such an event...
In this specific case, I would be getting fully prepared to abandon ship – but would not abandon until it became clear it was the best course of action. Essentially that means I know I'm going to loose my ship.
I would welcome the chance to discuss the “new” information given by Steve D'Antonio, but alas, I've no access to that information...
dj
To give a simplistic answer - you are likely not going to find the answer to this from manufacturers published information.
Ok, less simplistic answer below, but mind you - it's still a simplistic answer...
One needs to know the stability of the boat in the inverted position. What the data means stating "the vessel can recover from 130-degree knock-down" is that at 130 degrees the center of flotation is still higher than the center of gravity.
You have two concepts, the center of gravity and the center of flotation - the boat will remain in a position where the center of flotation is higher than the center of gravity unless forces act on the boat to move the boat into a position where the center of gravity is above the center of flotation and then the boat will move into a position where the center of flotation is higher than the center of gravity. In your case, once you move past 130 degrees the boat is going to go the "wrong way"...
The problem, is these two theoretical concepts are dynamic, not static. (They are also 3 dimensional...gets really complicated) Simply put, this means that these two points move with respect to each other as the boat moves. At 130 degrees (in your case), these two points are very close together, but they are still with the center of flotation higher than the center of gravity, so the boat will naturally right itself (keel down and mast up). Once the boat gets to 131 degrees, the center of flotation drops below the center of gravity and the boat will flip to where the mast is down and the keel is up - center of flotation higher than center of gravity.
Your question (and it is certainly not a dumb question) is - what does that 130 degrees mean in terms of self-recovery. The simple answer: nothing. The answer to that question is a function of how "stable" the boat is in that position once past 130 degrees. Think of the catamaran example given above. There you can easily see that the configuration of a boat with two widely placed hulls will be very stable both in a position of mast up and with mast down. As you can see, there is a lot of stability for a catamaran to stay upside down, once it gets there. What that means is the shape of the boat has an inherent "stability" to remain in the inverted position.
Now if you think about a mono-hull - you have that heavy keel, the mast, the hull shape all working when upright to keep your boat upright. Now, you go past that 130 degrees - what happens? To know the answer to this question, you need to know how stable or unstable the boat is in this "new" position. In a number of so called "blue water" sailboats, the curve of stability in the inverted position is very small. I've never actually seen published numbers for this - but I used to have a blue water sailboat where that 130 degree number you've used in the upright position - was probably something like 10 or 20 degrees in the inverted position. That boat actually went through a hurricane once and was completely rolled 3 times. But it never stopped in the roll - it got knocked down beyond the point of stability, and just continued to roll until back upright again. Of course all hatches and the companionway were closed so down flooding was minimal.
Hope this helps a bit....
dj
First here's the link to the article from the "Share" button. I don't know if you still have to jump hoops to read it.
'Always Step UP Into the Liferaft' Is Terrible Advice, Coast Guard Expert Says
'Ridiculous Old Maxim' Raised Again Recently After 'Jambo' Sinking
In case that doesn't work, the quotes from Mario Vittone are here:
Steve D'Antonio's comment in the comment section:
Mario Vittone is a prolific author on boating safety and runs the www.GCaptain.com website that covers the commercial shipping industry. He is well known for his coverage of the CGs investigation of the Bounty Sinking several years ago. That's how I became aware of him. Search for Mario Vittone Safety at sea to see his work on various platforms.
Steve D'Antonio
Oct 11, 2023
With the absolute highest respect for Vittone's accomplishments and unrivaled bravery, having attended, and lectured at, dozens of Safety at Sea seminars, I'm fairly well convinced that the "step up into your raft" axiom is not meant to be taken literally, it is a figure of speech for, "don't abandon ship too soon", because an adrift vessel is far easier to find than a raft, and this was well proven during the Fastnet Race disaster, where those who did abandoned ship for the seeming "safety" of a raft, regretted their decision. Stories of vessels abandoned while floating on their lines (and sails set in this story), which are later found safe and sound, are legion. But again, 'stepping up' isn't to be taken literally.
"His boat wasn’t sinking, but after a day fighting seasickness and fatigue, his wife and daughter could only lay below with his infant son. In a matter of hours, he would have to single-hand his 64 foot ketch through a hurricane after days without sleep." Presumably he didn't know how to heave to? His judgement has been questioned by many after this event, heading for Bermuda, with a hurricane on the way, a 4-month old baby on board and essentially no one for relief; in light of that, abandoning ship, for this family, probably was the right thing, but not leaving the dock would have been even better.
I wonder, how many vessels have been found, afloat, with missing rafts, and the crew is never found?
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Peter Swanson
Oct 11, 2023Author
I'm pretty sure he means it not just literally but metaphorically as well. He said it often enough and with examples. People die because they wait too long. Get into the liferaft while it is still easy to do so, he says over and over and over.
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Perry
Oct 15, 2023
I am pretty sure its a hard thing to generalise on, lot of variables. Am inclined to agree with you Steve, but then Vitone has more experience of this sort of thing than me. I suspect, however, that many just dont have the experience to judge when the moment is to 'Go'. Mind you that could include me, tho i have abandoned a boat, in good conditions, but holed (Main hull of a trimaran, it wasn't sinking) with a storm approaching, a reef behind me, out of water and my company being, at times, a salt water crock and a simply huge hammerhead -Torres Strait). The boat travelled a long way before being reported by a dive groupto have ground up against a reef and went down.
30 years ago i when considering buying a life raft I looked at stats that said a large proportion of people KNOWN to have gotten into Life rafts were never seen again. I bought a product called 'Floatpak'. Inflatable bags to keep ditched helicopters afloat, but in my case tied into the floors of my 12m boat about to do a Sthn Ocean passage.
Its not a terribly bad idea, we regularly tell people to 'stay with the car' here in the desert in Australia and lots dont and pretty much all of them die.
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Peter Swanson
Oct 15, 2023Author
Let's not forget the advances in liferaft designs since many of those cases of individuals lost after abadoning ship. That includes a ballast baffle to hep prevent capsizing.
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Perry
Oct 15, 2023
Probably a consideration. And i didnt know this. Now Im not trying to just be argumentative, as really i have no expertise in this area, I have heard from several friends who have taken liferafts to be serviced who were told the LR was too old to be re certified. And then further told, off the record, that it was of a far better build than newer ones.
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Steve D'Antonio
Steve D'Antonio Marine Consulti…
Oct 15, 2023
30 years ago EPIRBs were large, cumbersome and expensive. Their small size and low cost now means no vessel should be without one, with rescue far more likely and happening far more quickly. I firmly believe your best chances are with a vessel that is afloat rather than in a raft. I've spent a short time in a raft, for training, and it is a horrible experience. There is a tendency for those who are seasick or frightened to believe a raft will make them feel better an be less frightened, it won't. Now, staying with a vessel that is afloat when rescue is at hand, a scenario that was mentioned, is an entirely different scenario, if conditions are forecast to worsen and rescue may not be available later, then abandoning a floating ship may indeed make sense. I suppose the mantra should be, "Don't abandoned ship, for the for the perceived safety of a raft, until the raft becomes safer than the ship".
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Steve D'Antonio
Steve D'Antonio Marine Consulti…
Oct 15, 2023
Several years ago, I installed a floatation system on one vessel, at a client's request. A couple of years later the manufacturer folded up shop when it was discovered the bags didn't have the requisite floatation for supporting ballasted sailing vessels. I suppose for a cat it could work.
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Curt Nixon
Oct 12, 2023
Exactly...and I was the first to post the question of timing. Each case is unique for sure but the decision should be balanced by the risk placed on others in the recovery...and likelihood of managing a self repair. It was Martin's decision to make and he made it. There is nothing wrong with questioning the facts after the event. It is how we improve. The facts are still very sketchy.
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I probably just violated a bunch of IP fair use rules, but this topic is important.
No, I don't think you violated rules - it is permissible to quote sections of a document, not the whole document, for reasons of clarity and discussion - without remuneration involved...
Having read through it all (no, I can't read the original without all the crap...), my short summary is there is no change in the metaphorical phrase of "step up into your life-raft". But yes, indeed, it is metaphorical. One really must take into account the circumstances of why one is thinking to abandon ship and what you are subsequently faced with through abandonment and in that abandoned ship condition.
Talking through some of the specific case histories where explanations of the circumstances surrounding the decision, both when it should be done and when it shouldn't be done, is very beneficial to gain a better understanding to the boundaries of the metaphor.....
That being said, I will confess it does seem to have a component of what I call "the talking heads" syndrome - where "experts" simply blather on about something seemingly like they must maintain some kind of "exalted" position.... However this subject is, as you state, very important and there is enough "meat" in here to keep me interested..
Thank you for this, it has actually been very useful for me.
dj
p.s. Apologies if I have been excessively blunt...
Having read through it all (no, I can't read the original without all the crap...), my short summary is there is no change in the metaphorical phrase of "step up into your life-raft". But yes, indeed, it is metaphorical. One really must take into account the circumstances of why one is thinking to abandon ship and what you are subsequently faced with through abandonment and in that abandoned ship condition.
Talking through some of the specific case histories where explanations of the circumstances surrounding the decision, both when it should be done and when it shouldn't be done, is very beneficial to gain a better understanding to the boundaries of the metaphor.....
That being said, I will confess it does seem to have a component of what I call "the talking heads" syndrome - where "experts" simply blather on about something seemingly like they must maintain some kind of "exalted" position.... However this subject is, as you state, very important and there is enough "meat" in here to keep me interested..
Thank you for this, it has actually been very useful for me.
dj
p.s. Apologies if I have been excessively blunt...
Blunt is OK, rude, antagonistic, excessively argumentative, not so much.
For what it's worth, we live in a headline media environment. Simplistic overstatements of complex subjects, ignoring the nuances of an important issue, and so forth dominate the conversation. We all benefit from pushing back on simplistic overstatements (or under statements). On SBO we should all strive to be fair and accurate in the advice we give and eschew tired old phrases that gloss over complex issues.
We are very much in agreement. Hope I didn't come off as otherwise. I quite like your "headline media environment" description... Factoids devoid of facts are more the norm.... Some subjects are far worse than others.
The specific discussion surrounding the Marine Flower II provided two points of view I found quite useful. On the one hand, abandoning ship when they did was a good decision at that time - the fact they probably shouldn't have left the dock would have likely been a better decision. I'd add to that, given the crew, boat size and where they were heading, the other option would have been to bring on competent crew if not staying at the dock. A lesson in that, not brought out, is that we each as captains of our ships need to do seriously accurate self-evaluations of our capabilities, crew capabilities and ship capabilities - not done with hubris....
dj
To make this short and sweet, I was capsized 3 times in a hurricane (cyclone, typhoon or whatever one calls them where you are from) on a 65' hermaphrodite ketch launched in 1909. For some reason that old gal had wooden spars instead of alloy when she was built and they brought us back from each capsize very quickly, all of which were very close to 180 degrees. Not to say we weren't nearly half full of water, which required many hours of hard work bailing the boat out with pumps, and at times, buckets.
Now, that's BS you might say, but the ballast stones in the bilge ended up on the knotty pine ceiling, leaving seriously significant reminders of their travel, before they fell back, once she began to right herself.
If you want every possible chance of surviving a capsize at sea, just accept the maintenance on your solid wood spars and get out the old block and tackle twice a year. and your favorite varnish brush. Were I younger, much younger, I'd certainly want to do the GGR, but with wooden spars, thank you.
Now, that's BS you might say, but the ballast stones in the bilge ended up on the knotty pine ceiling, leaving seriously significant reminders of their travel, before they fell back, once she began to right herself.
If you want every possible chance of surviving a capsize at sea, just accept the maintenance on your solid wood spars and get out the old block and tackle twice a year. and your favorite varnish brush. Were I younger, much younger, I'd certainly want to do the GGR, but with wooden spars, thank you.
Current off-shore racing requirements mandate that floorboards be locked in place so if you do this kind of roll, things stay down closer to where they are designed to be. I do like the flotation aspects of wooden spars, but not the maintenance aspect...
There were cats that were designed with inflatable balloons on the mast head that could be inflated to bring a flipped cat back up - I don't know if they still do that...
dj