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#1
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Seaworthiness
Again, I point at Sayula II. Tough boat, but a whole lot faster than a
Colin Archer. As for outracing the weather at sea, if I have a hurricane forecast in front of me, with pretty good track guesses from the NHC, I'd rather have a boat that was a modern, fast, tough, seaworthy design, rather than an old, slow, tough, seaworthy design. Not extreme, but taking into account modern design thinking. For example, there's some evidence that a modern keel and skeg design is less likely to "trip" on a wave and capsize, than the old full keel designs. Certainly modern designs with the rudder way aft have more steering leverage and therefore will steer better in extreme conditions than long keels with attached rudder. Swee****er (Swan 57) has a D/L of about 230. She certainly never gave us any concerns on our circumnav and I would believe she is sufficiently seaworthy for all "ordinary" purposes -- no Southern Ocean work, I think. A 230 D/L does not mean "weak" as a simple glance around at the scantlings of a Swan will show you. As far as references go, my favorite single book is Desirable and Undesirable Characteristics of Offshore Yachts, The Technical Committee of the Cruising Club of America, John Rousmaniere, Ed., W.W. Norton, 1987. While written partly in response to Fastnet 1979, by an organization best known for racing, the authors have 750,000 miles at sea in small boats among them, and it is good reading for any cruiser planning to venture out of the sight of land. Tony Marchaj, cited earlier in this thread, has also written several books with good information on the good, the bad, and the ugly in offshore design. -- Jim Woodward www.mvFintry.com .. "William R. Watt" wrote in message ... define "seaworthiness" I thought it meant a boat that would take care of itself in rough conditions, not a boat that could perhaps outrace the weather. This outracing the weather is only helpfull along the coast where, given advance warning of deteriorating weather conditions over the radio, the faster boat can run for cover. Its not much help mid ocean in a big weather system. The main indicator of seaworthiness is the displacement to length ratio. Boats with a ratio over (I think) 300 are the most seaworthy. These are ocean going cruisers. Because boats are sold by the pound they are expensive. I know lighter materials can cost more per pound by they don't have as many pounds. The heavy cruisers also have more room for accomdation and storage and a better comfort factor. They can make good time under all conditions but light winds. There are books on cruising sailboats as distinct from racing and coastal sailboats. One that I read recently is Danny Greene's "Cruising Sailboat Kinetics" (1984). -- -------------------------------------------------------------------------- ---- William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
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#2
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Seaworthiness
Peter Ward wrote:
I guess I was thinking of seaworthiness in the fairly narrow sense of being able to survive something like 'The Perfect Storm'; & particularly the ability to quickly self-right in the event of capsize. According to Czeslaw A. Marchaj in 'Seaworthiness : The Forgotten Factor' the "point of vanishing stability" et.al. of most modern yacht designs is woefully inadequate There are some fairly simple ways to evaluate the relative stability of a sailboat, and there is a very wide range of boats on the market. To say 'modern yacht designs' have *any* single factor in common is like saying 'modern motor vehicles' are all thus-and-so. How about we say 'some popular modern yacht designs are woefully inadequate'? Then the trick is much simpler, just avoid these particular ones. As a natural pessimist, I want to build the 'ultimate-unsinkable' craft, which will weather the worst that the sea can inflict; As a natural pessimist myself, let me assure that such a thing does not exist. The ocean is incredibly powerful, it can tear up battleships & supertankers when it's in the mood to. The only answer for surviving such conditions in a small sailboat is.... be elsewhere.... That said, a high ballast displacement ratio and full positive flotation make a lot of sense for ocean passagemaking sailboats. "William R. Watt" wrote... define "seaworthiness" I thought it meant a boat that would take care of itself in rough conditions That is a good quality to have, but it can also include having the right gear such as a drogue and/or a storm staysail. .... not a boat that could perhaps outrace the weather. This outracing the weather is only helpfull along the coast where, given advance warning of deteriorating weather conditions over the radio, the faster boat can run for cover. Its not much help mid ocean in a big weather system. I disagree strongly. A boat that can make good miles, especially reaching or close reaching in a seaway, is going to spend a lot less time in a storm system and will be able to keep further away from the center. The main indicator of seaworthiness is the displacement to length ratio. Boats with a ratio over (I think) 300 are the most seaworthy. These are ocean going cruisers. Because boats are sold by the pound they are expensive. I know lighter materials can cost more per pound by they don't have as many pounds. The heavy cruisers also have more room for accomdation and storage and a better comfort factor. They can make good time under all conditions but light winds. And to windward, usually. The issue here is that a lot of the current generation like heavy heavy boats. Therefor, since so many of the boats out there cruising are heavyweights, the statistical evidence that heavy boats make the best cruisers is self perpetuating. Heavy boats are good at one thing.... not getting bounced around. Weight conveys no advantage beyond simple inertia. Jim Woodward wrote: Again, I point at Sayula II. Tough boat, but a whole lot faster than a Colin Archer. As for outracing the weather at sea, if I have a hurricane forecast in front of me, with pretty good track guesses from the NHC, I'd rather have a boat that was a modern, fast, tough, seaworthy design, rather than an old, slow, tough, seaworthy design. Not extreme, but taking into account modern design thinking. For example, there's some evidence that a modern keel and skeg design is less likely to "trip" on a wave and capsize, than the old full keel designs. Certainly modern designs with the rudder way aft have more steering leverage and therefore will steer better in extreme conditions than long keels with attached rudder. They will also respond better with less work by either helmsman or autopilot. A tired helmsman is a poor safety factor to have in big breaking seas. Swee****er (Swan 57) has a D/L of about 230. She certainly never gave us any concerns on our circumnav and I would believe she is sufficiently seaworthy for all "ordinary" purposes -- no Southern Ocean work, I think. A 230 D/L does not mean "weak" as a simple glance around at the scantlings of a Swan will show you. Further point, heavily built is not necessarily stronger. Polyester resin is brittle. In an early edition of his book on building the Westsail 32, Ferenc Mate advocated using resin & newspaper to block in parts of the hull. This is going to add zero strength. Lots of older boats with very thick hulls are actually weaker due to the use of short strand mat, chopper guns, lots of voids, cloth edges at odd points, etc etc. All else being equal, heavier is usually stronger. But 'all else' never is quite equal, and the strongest boats are the ones that are well engineered and properly built with suitable materials. This doesn't happen by accident. Fresh Breezes- Doug King |
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#3
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Seaworthiness
DSK wrote in message ...
[snip good stuff] As a natural pessimist, I want to build the 'ultimate-unsinkable' craft, which will weather the worst that the sea can inflict; As a natural pessimist myself, let me assure that such a thing does not exist. The ocean is incredibly powerful, it can tear up battleships & supertankers when it's in the mood to. __________________________________________________ ______________________________ The only answer for surviving such conditions in a small sailboat is.... be elsewhere.... -------------------------------------------------------------------------------- After noting all of the very sage advice throughout this thread, I suspect this is in fact the zen-essence of seaworthiness: minimize the statistical likelihood that you will be caught in an ultimate storm & trust the balance of fate to the Sea Gods & your own contingency planning. On this point one of the less funny things that has happened to me, is watching the Skipper of a sinking Indonesian ferry - overloaded with wailing Indonesians - throwing prayer leaflets off the bow in order to appease the Sea Gods. That said, a high ballast displacement ratio and full positive flotation make a lot of sense for ocean passagemaking sailboats. [edit] |
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#4
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Seaworthiness
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#5
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Seaworthiness
"William R. Watt" wrote in message ... define "seaworthiness" I thought it meant a boat that would take care of itself in rough conditions, not a boat that could perhaps outrace the weather. This outracing the weather is only helpfull along the coast where, given advance warning of deteriorating weather conditions over the radio, the faster boat can run for cover. Its not much help mid ocean in a big weather system. Sorry to disagree but some years ago, during a westward Atlantic crossing, we became threatened by a tropical storm that later developed in a hurricane. My boat was fast enough to efficiently take the classic escape course from such a system. It was my fault to cross to early in season but the fast boat made all the difference and kept us safe, right in the middle of the ocean. -- Jacques http://www.bateau.com |
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#6
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Seaworthiness
Yacht design and especially boat building materials have progressed since
the designs you list. They may have been the best 100+ years ago but it's like saying that the Ford model T is the best car ever built! Try some books like "Seaworthiness" by Marchaj or check books by Dave Gerr. It is undeniable that the boats who rcae aorund the world today are more seaworth than a Colin Archer. PS: a judgement about seaworthiness should not be based on fear of the sea .. . . -- Jacques http://www.bateau.com "Peter Ward" wrote in message m... From random reading I've formed the impression that the Bristol Channel Pilot Cutter is the epitome of a seaworthy design. Colin Archer designs seem to get the big tick also. |
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#7
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Seaworthiness
"Jacques Mertens" wrote in message ...
Yacht design and especially boat building materials have progressed since the designs you list. They may have been the best 100+ years ago but it's like saying that the Ford model T is the best car ever built! Point taken; however, I can't help but note that modern mathematicians are coming round to the view that the archaic 'oceanic lateen' sail design - developed by ancient Polynesians over 4,000 years ago - is actually more 'efficient' than the modern Bermudan. I would have thought it quite possible that the 'ye olde worlde' designers may well have hit upon the 'Platonic Ideal' of ultimate seaworthy hull design via the school of very hard knocks & near-death epiphanies. Try some books like "Seaworthiness" by Marchaj or check books by Dave Gerr. It is undeniable that the boats who rcae aorund the world today are more seaworth than a Colin Archer. I'm sure you're correct - but are they "more seaworthy" because of superior design or superior construction or a mix of both? I personally prefer this definition of seaworthy: "define "seaworthiness" I thought it meant a boat that would take care of itself in rough conditions, not a boat that could perhaps outrace the weather." [rom: William R. Watt ) Subject: Seaworthiness Newsgroups: rec.boats.building Date: 2003-11-10 13:50:05 PST ] Someone in an earlier post mentioned that the Westsail 32 is proven seaworthy by virtue of having actually survived 'The Perfect Storm' without human intervention ...so I do a quick google search & lo & behold up comes something which could be quite easily be mistaken for a Bristol Channel Pilot Cutter in a dark seaway & has a blue-blood Colin Archer pedigree to boot!!: http://www.boatus.com/jackhornor/sail/Westsail32.htm PS: a judgement about seaworthiness should not be based on fear of the sea . . . A very prescient observation. I don't mind admitting that I do in fact have a healthy fear of the sea ...& it is in fact the primary motivating factor in my quest for the *_most seaworthy_* design & construction available for a vessel under 35'. One of my formative late-life experiences was being caught on what the locals call a "crook crossing" of Bass Strait (Devonport Tas. to Melbourne Vic.) some years ago. I was on exactly the same type of ferry that foundered in the Baltic whilst crossing from Estonia to Sweden in 1994; it was a massive vessel of many thousands of tons displacement but literally being bounced & wracked like a balsa model in what looked very much like a watery version of Dante's Inferno. The only shared religious experience I've had in my entire life in fact. -- Jacques http://www.bateau.com "Peter Ward" wrote in message m... From random reading I've formed the impression that the Bristol Channel Pilot Cutter is the epitome of a seaworthy design. Colin Archer designs seem to get the big tick also. |
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#8
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Seaworthiness
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#9
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Seaworthiness
Just to finish the story - the above-mentioned experience gave me a
quasi-mystical insight into the awesome power of the sea. For anyone who's never heard the obscene shrieking of triple screws unsheathed from the brine at full power for minutes at a time as a gargantuan vessel pitches, rolls & yaws simultaneously to the extremes of the envelope; followed by the thunderous explosion of a flat-face bow smashing into a bottomless trough at thousands of tonnes mass ...then loop the sequence for hours on end; it's probably difficult to conjure just what horrors the sea can deliver I now understand why coconuts-in-husk are probably the only *_truly seaworthy_* design. However the 'takeaway' from all of the exceptionally good advice on offer in this thread appears to be that 'seaworthiness is a multi-dimensional challenge' & preparing for the worst involves garnering a wide range of skills & resources ...including a first rate liferaft & epirb. If "fear of the sea" inspires one to take every precaution possible right from the getgo, in order that others will not have to put their lives at risk in order to extract one from what would otherwise be one's watery grave; then surely its not such a bad thing? |
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#10
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Seaworthiness
I agree with you, it's not a black and white situation. I have respect for
the sea but too often, questions about seaworthiness reflects a fear of the unknown. I lost a few friends at sea, one very close and after that loss, for while, I had a real but irrational fear of making any passage longer than 50 NM. It's gone know but respect for the sea is still there. My attitude is more of a "Inch'Allah" type: I do all what I can to have a good boat and be well prepared, to a point and after that, I'll handle it as it comes. Your words: "quasi-mystical insight into the awesome power of the sea" are exactly how I feel. Respect for the sea doesn't mean that passive safety should be an overwhelming priority in choosing a boat or a design, that's what I wanted to say. -- Jacques http://www.bateau.com "Peter Ward" wrote in message ... Just to finish the story - the above-mentioned experience gave me a quasi-mystical insight into the awesome power of the sea. For anyone who's never heard the obscene shrieking of triple screws unsheathed from the brine at full power for minutes at a time as a gargantuan vessel pitches, rolls & yaws simultaneously to the extremes of the envelope; followed by the thunderous explosion of a flat-face bow smashing into a bottomless trough at thousands of tonnes mass ...then loop the sequence for hours on end; it's probably difficult to conjure just what horrors the sea can deliver I now understand why coconuts-in-husk are probably the only *_truly seaworthy_* design. However the 'takeaway' from all of the exceptionally good advice on offer in this thread appears to be that 'seaworthiness is a multi-dimensional challenge' & preparing for the worst involves garnering a wide range of skills & resources ...including a first rate liferaft & epirb. If "fear of the sea" inspires one to take every precaution possible right from the getgo, in order that others will not have to put their lives at risk in order to extract one from what would otherwise be one's watery grave; then surely its not such a bad thing? |
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