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Thread: C.A Marchaj ?

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    Default C.A Marchaj ?

    My ill-formed question is how this book from 1964 holds up in current design theory? Especially regarding bow-wave / stern wave interaction.

    I did a search on this forum for this author and ended up with a couple pages of threads but they were listed as the whole threads, rather than by the specific hit, so it is difficult to tunnel into the stuff and get a concise picture. If someone can help me get a better reading list, I'll go do my homework and hopefully will be able to ask a better question.

    Thanks,

    Ken

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    Default Re: C.A Marchaj ?

    I have Marchaj's books Sailing Theory and Practice, The Aero-Hydrodynamics of Sailing, and Seaworthiness: The Forgotten Factor and find them all relevant to my work. I especially like Seaworthiness, as its point is close to my design philosophy - boats have to be safe, as well as good-looking, fast, commodious, etc.
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    Default Re: C.A Marchaj ?

    Quote Originally Posted by kbowen View Post
    My ill-formed question is how this book from 1964 holds up in current design theory? Especially regarding bow-wave / stern wave interaction.

    I did a search on this forum for this author and ended up with a couple pages of threads but they were listed as the whole threads, rather than by the specific hit, so it is difficult to tunnel into the stuff and get a concise picture. If someone can help me get a better reading list, I'll go do my homework and hopefully will be able to ask a better question.

    Thanks,

    Ken
    There is no reason to think that Marchaj has been superseded on wave making and bow/stern wave system interaction. It is basic physics.
    So yes, please come back with a more specific question.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: C.A Marchaj ?

    My more specific question: I am currently building a "Western Lakes Mackinaw" per Chapelle ASSC. This has very fine aft sections below the LWL, though due to the drag of the keel the LCB is still at about 55% of the LWL. Could I expect this hull to drag less of a quarter-wave than a more modern design? Marchaj sometimes reads as though the specific hull shape doesn't matter, and that it's all about displacement and speed. This is relevant to me because there is damn little room around the tiller due to the fine lines aft, and I have fashioned an elliptical expansion of the aft cockpit to accommodate humans. this leaves very thin wash-decks that far aft, and I wonder if I will need to add a tall cockpit combing to keep the slop out? If the Forum gods smile, there is a photo, shown with canvas deck in process, please advise:

    Ken
    IMG_4516.jpg

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    Default Re: C.A Marchaj ?

    Quote Originally Posted by kbowen View Post
    My more specific question: I am currently building a "Western Lakes Mackinaw" per Chapelle ASSC. This has very fine aft sections below the LWL, though due to the drag of the keel the LCB is still at about 55% of the LWL. Could I expect this hull to drag less of a quarter-wave than a more modern design? Marchaj sometimes reads as though the specific hull shape doesn't matter, and that it's all about displacement and speed. This is relevant to me because there is damn little room around the tiller due to the fine lines aft, and I have fashioned an elliptical expansion of the aft cockpit to accommodate humans. this leaves very thin wash-decks that far aft, and I wonder if I will need to add a tall cockpit combing to keep the slop out? If the Forum gods smile, there is a photo, shown with canvas deck in process, please advise:

    Ken
    IMG_4516.jpg
    As to wake, she has a nice flat run, so should slip along easily.
    She is fine aft, but does fill out to provide reserve buoyancy in the stern quarter, so she should lift to any following seas.
    The original coamings were low and the wash decks were narrow, so I don't think you need worry so much.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: C.A Marchaj ?

    Thanks for the reply. I am currently on a family vacation away from the build, and am trying to do whatever homework I can for when I return to the boat.

    Ken

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    Default Re: C.A Marchaj ?

    Quote Originally Posted by kbowen View Post
    Thanks for the reply. I am currently on a family vacation away from the build, and am trying to do whatever homework I can for when I return to the boat.

    Ken
    Fairy nuff.
    Just don't try to cram a 4 year degree course plus years of experience into a few weeks reading.
    The boat that you are building evolved a fitness for purpose. Your changes are minimal in the scheme of things. If you do find that she is a tad wet aft, you can always add to the coaming height after you have used her and are ready to do a repaint and refit.
    Like with a new home, live with it for a year or so and then see what improvements are required.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: C.A Marchaj ?

    Has anybody actually set eyes on a boat designed by Marchaj?

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    Default Re: C.A Marchaj ?

    Quote Originally Posted by John Meachen View Post
    Has anybody actually set eyes on a boat designed by Marchaj?
    Career[edit]

    In 1953, drawing on his professional background in aerodynamics, Czeslaw Marchaj designed modifications (within class rules) to his Finn class racing boat and subsequently sailed it to a surprising win in a multiday Warsaw-Gdańsk river regatta. Asked by the Warsaw sailing clubs community about his race performance, he prepared and presented a series of lectures on sail aerodynamics during 1953/54 winter off-season. These lectures had been edited into the first version of the book "Sailing Theory and Practice". This work had been well received and published in Poland and abroad.[Note 4]
    On the strength of "Sailing Theory...", in 1969, Czesław Marchaj was granted a two-year scholarship by the University of Southampton. In 1970 he decided to live in United Kingdom (which was considered defection by Polish authorities and resulted in a long term separation from his family which was barred from leaving Poland to join him).[3] In the years 1969-1990 Czesław Marchaj continued research at University of Southampton[Note 5] and was a visiting lecturer at multiple top ranking academic institutions. At University of Southampton he pioneered wind tunnel testing of (scaled) sailing ships[4] His work included books "Aero-Hydrodynamics of Sailing" (1979), "Seaworthiness: The Forgotten Factor" (1986) and "Sail Performance: Techniques to Maximize Sail Power" (1996). In 1977, after many boats were sunk with a loss of life in the Admirals Cup regatta, Czesław Marchaj was commissioned to investigate the problem of dynamic instability of yachts in foul weather.[Note 6] He was also involved in the America's Cup competition bid preparations for the British team.[Note 7]
    His books contain a rigorous theoretical and experimental approach to issues in design and operation of sailing vessels, resulting in detailed analysis, confirmation or debunking of many previously assumed facts in sailing practice.
    https://en.wikipedia.org/wiki/Czes%C5%82aw_Marchaj

    That do you?
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: C.A Marchaj ?

    It tells me about as much as the biography of the man that appeared in Yachts and Yachting about thirty years ago.It doesn't actually refer to boats of his design and I am a little curious about discovering some.

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    Default Re: C.A Marchaj ?

    I think his books are seminole works for folks seriously into the theory of how boats....particularly small sailing boats behave. I don't think his work on seaworthiness goes far enough. It does not go deep enough into stability, it does not talk enough about watertight integrity....this is presumed at best. It does not really discuss structural integrity, hull, deck, cabin, hatches, doors, ports , scuttles, vents....etc . Systems integrity, engine, pumps,.....hmissed ......

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    Default Re: C.A Marchaj ?

    Quote Originally Posted by John Meachen View Post
    It tells me about as much as the biography of the man that appeared in Yachts and Yachting about thirty years ago.It doesn't actually refer to boats of his design and I am a little curious about discovering some.
    He earned his living as an academic. Apart from that Finn that kick started his career, why do you thing that designing boats is important?

    Are Admiral Taylor or Willy Froud remembered for designing boats?
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: C.A Marchaj ?

    Quote Originally Posted by gilberj View Post
    I think his books are seminole works for folks seriously into the theory of how boats....particularly small sailing boats behave. I don't think his work on seaworthiness goes far enough. It does not go deep enough into stability, it does not talk enough about watertight integrity....this is presumed at best. It does not really discuss structural integrity, hull, deck, cabin, hatches, doors, ports , scuttles, vents....etc . Systems integrity, engine, pumps,.....hmissed ......
    Much of that is and has been adequately covered elsewhere, although he does discuss the need for adequate strength in the deck and its hatches.
    He is important for addressing stuff that was being ignored by the marketing men and racing rule derivers who were driving design in directions that were to the detriment of safety.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: C.A Marchaj ?

    Prof. Marchaj was a physicist with an interest in sailing who advanced the science of understanding how sailboats work; he was not a naval architect or boat designer. Similarly, Thomas Simpson of Leicestershire, England was an 18th-century mathematician whose development of a numerical approach to finding definite integrals is fundamental to calculating volume, displacement and stability of ships was not a naval architect or designer and, as far as I know, never designed a ship.
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    Default Re: C.A Marchaj ?

    I have to admit to being puzzled that a man working in the field didn't actually seek to put his academic work into practice by designing a boat that incorporated his findings.We might all have benefitted by observing the qualities of such a boat.

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    Default Re: C.A Marchaj ?

    Quote Originally Posted by John Meachen View Post
    I have to admit to being puzzled that a man working in the field didn't actually seek to put his academic work into practice by designing a boat that incorporated his findings.We might all have benefitted by observing the qualities of such a boat.
    Well, I guess that you know, none better how many manhours it takes to design a boat. Marchaj had his living to make, teaching duties at his university plus research commissions. Who would pay his wages whilst he designed this boat?

    IIRC from wayy back when I read his book, he discusses general principles to be followed or avoided, rather than specific engineered design solutions.
    It really is quite difficult to build an ugly wooden boat.

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    Quote Originally Posted by Peerie Maa View Post
    Much of that is and has been adequately covered elsewhere, although he does discuss the need for adequate strength in the deck and its hatches.
    He is important for addressing stuff that was being ignored by the marketing men and racing rule derivers who were driving design in directions that were to the detriment of safety.
    Statistically, the lightweight racing machines in both the '79 Fastnet and '98 Hobart did as well as the cruisers in some respects, pretty much. A while back I dug around some old yachting magazines to identify Class V boats and look at how they fared. If I recall correctly, 6 of the 11 "lightweight radical" 30-32 footers had knockdowns while 6 of the 12 "seaworthy conservative" Contessa 32s had knockdowns. That's a statistically insignificant difference. A couple of the light boats rolled, but we're dealing with a very small database and it can be said that at least some of the problem was the way they were handled. Given the other factors involved it may have been that the "racing machines" were unfairly criticised.

    I think over half the casualties in the '79 Fastnet arose when people felt that boats that survived the storm were going to sink. Those people then got into rafts that failed (Gunslinger, Ariadne, and Trophy IIRC) or stayed on deck and sufferent hypothermia etc (Grimalkin). The boats then survived after being abandoned. The fear killed more people than the actual danger, so arguably heightening such fears is the wrong way to look at the subject.

    People like Marchaj also may have been a bit inconsistent when identifying issues. The skipper of Grimalkin arguably died because of gear problems in a knockdown, but his death seems to have been ascribed to a boat problem whereas the death of two sailors from the conservative Ohlson 35 Flashlight from gear problems in a knockdown is ascribed to a gear problem.

    In the '98 Hobart, the biggest problem (in terms of deaths and sinkings) were long keel boats not designed to any rule. So IMHO it seems to be hard to find evidence that the boats were as bad as Marchaj claimed.

    Marchaj's wind tunnel tests on rigs also seem to be odd. On the topic of mast/mainsail interaction I think the smallest mast he tested was a round spar 10% of the foot length. That is an unrealistically big mast and later CFD work, as well as many decades of real world experience, indicates that his claims about the unfavourable effect of masts on mainsail efficiency appear to be grossly exaggerated.

    I also find it rather odd that in one work he advocated standing up in Finns downwind. Yes, his reasoning in some respects was correct, but he ignored the other problems involved. We know that the great Finn sailors of his day could stand up in their Finns downwind, but they did not do so when racing. For a far slower sailor like Marchaj to tell Mankin and Elvstrom that they were sailing their Finns wrongly was a big stretch, IMHO, and may indicate that Marchaj tended to fixate on the wrong issues to some extent.
    Last edited by Chris249; 08-05-2019 at 08:38 AM.

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    Default Re: C.A Marchaj ?

    Quote Originally Posted by Chris249 View Post
    Statistically, the lightweight racing machines in both the '79 Fastnet and '98 Hobart did as well as the cruisers, pretty much. The skipper of Grimalkin suffered a head injury from loose gear in a knockdown, but his death seems to have been ascribed to a boat problem whereas the death of two sailors from the conservative Ohlson 35 Flashlight from faulty gear in a knockdown is ascribed to a gear problem.

    A while back I dug around some old yachting magazines to identify Class V boats and look at how they fared. If I recall correctly, 6 of the 11 "lightweight radical" 30-32 footers had knockdowns while 6 of the "seaworthy conservative" Contessa 32s had knockdowns. A couple of the light boats rolled, but we're dealing with a very small database and it can be said that at least some of the problem was the way they were handled.

    In the '98 Hobart, the biggest problem (in terms of deaths and sinkings) were long keel boats not designed to any rule. So IMHO it seems to be hard to find evidence that the boats were as bad as Marchaj claimed.

    Marchaj's wind tunnel tests on rigs also seem to be odd. On the topic of mast/mainsail interaction I think the smallest mast he tested was a round spar 10% of the foot length. That is an unrealistically big mast and later CFD work, as well as many decades of real world experience, indicates that his claims about the unfavourable effect of masts on mainsail efficiency appear to be grossly exaggerated.
    Misses the point of his thesis if I recall correctly.

    Racing machines are exhausting, they have to be sailed every inch of the way, so their clones were dangerous cruising boats.
    For a cruising boat you need to have a craft that can be left alone to look after itself. Which marketing and human nature missed entirely when dazzled by some over blown dinghy form with a directionally unstable keel configuration.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: C.A Marchaj ?

    isses the point of his thesis if I recall correctly.

    Racing machines are exhausting, they have to be sailed every inch of the way, so their clones were dangerous cruising boats.
    For a cruising boat you need to have a craft that can be left alone to look after itself. Which marketing and human nature missed entirely when dazzled by some over blown dinghy form with a directionally unstable keel configuration.
    I'd agree. One of my biggest takeaways from reading Marchaj, was that the crew must be taken into account when assessing a vessel's seaworthiness; the crew--its experience, fitness, and readiness--is a big component of seaworthiness.


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    Default Re: C.A Marchaj ?

    CA Marchaj in memoriam

    1979, the forgotten factor

    IMO

    (A) These sailboats could not surf, because:

    (1) a great great great destabilizing/yaw Hull moment, the so called "Munk Moment" (Max Michael Munk): many sailboat designers don't know how to calculate it, and others did not even hear about the existence of this Problem

    (2) D/L > 200: the Force of Gravity drives the sailboat with enormous force and the sailboat cannot dissipate the energy, and the resistance is piled up in front of the center of gravity

    (3) hydrodynamic center of the Keel forward of the longitudinal position of the center of gravity

    1 + 2 + 3 = kaputt

    (B) on the other hand there is no way to leave the sailboat standing still safely

    from my point of view the solution is ...

    a light (D / L < 150) or ultra light (D/L =< 100) surfboard ... with neutralized* Keel and two rudders ... and capable of heaving-to with sea anchor taking the rudder blades out of the water

    another solution is going back to ... T. Harrison Butler

    *: hydrodynamic center of the Keel very near the longitudinal position of the center of gravity of the sailboat

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    Whether racing machines of that type are exhausting seems to vary according to the observer. Some people say that they are easier to sail than more conservative designs because things like sheet loads are lower, and the lighter boats take less green water. A guy I know steered for about 10 hours through the Fastnet storm, which seems to indicate that it was not physically exhausting. Another guy I've sailed with said that in the '98 Hobart his light IOR boat was less exhausting than his previous S&S classic, because it took less green water aboard due to the higher freeboard and lighter displacement.

    The pic of Grimalkin shows a boat that survived even after its active crew left it to the mercy of the seas.

    I don't know how it can be said that the type of boats that were criticised by Marchaj can't surf - they clearly can, and we did it at the time.

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    Default Re: C.A Marchaj ?

    Quote Originally Posted by Chris249 View Post
    Whether racing machines of that type are exhausting seems to vary according to the observer. Some people say that they are easier to sail than more conservative designs because things like sheet loads are lower, and the lighter boats take less green water. A guy I know steered for about 10 hours through the Fastnet storm, which seems to indicate that it was not physically exhausting. Another guy I've sailed with said that in the '98 Hobart his light IOR boat was less exhausting than his previous S&S classic, because it took less green water aboard due to the higher freeboard and lighter displacement.

    The pic of Grimalkin shows a boat that survived even after its active crew left it to the mercy of the seas.

    I don't know how it can be said that the type of boats that were criticised by Marchaj can't surf - they clearly can, and we did it at the time.
    Could the helmsman go below to make a brew?
    There is mental as well as physical fatigue.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: C.A Marchaj ?

    Did any helmsmen in the top medium-size boats, of whatever age or type, go down below to make a brew at the peak of the storm?

    Incidentally the boat that probably had just about the lightest DLR of any boat in the fleet, the Joubert 2 tonner Accanito, was later used for years as a world cruiser. She still had the same stripped out interior, flush deck, spade rudder and spindly fractional rig with runners, and the couple who lived aboard regarded her as an excellent cruiser when I met them in Australia.

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    Default Re: C.A Marchaj ?

    Chris youll never get past the old farts who desperately cling to "tradition". fact is modern boats are much safer and easier to sail that the old clunkers. They have to retreat below because they can hardly get out of their own way! Lighter is usually better and larger is usually safer.
    whatever rocks your boat

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    Default Re: C.A Marchaj ?

    This is starting to sound like Republicans vs. Democrats. I have read quite a lot about the Fastnet and Hobart race disasters - both technical treatises and anecdotal narratives - and seen a lot of the comparative statistics about both races. I find it fascinating how different people can read the same data and reach different conclusions. And, of course, they disparage the other side and call them and their promoted boat types derogatory names. Just like politics, eh?
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    Default Re: C.A Marchaj ?

    As with politics, more acrimony calls forth less systematic knowledge brought forward more and more redundantly with diminishing relevance to Marchaj's actual theses.

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    Default Re: C.A Marchaj ?

    I'm sayin' nowt.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: C.A Marchaj ?

    I love the diagrams in his book similar to this one. main-qimg-7ee4f2e7cc2793d04097aeb7dd7805cf.jpg

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    Default Re: C.A Marchaj ?

    Quote Originally Posted by mmd View Post
    This is starting to sound like Republicans vs. Democrats. I have read quite a lot about the Fastnet and Hobart race disasters - both technical treatises and anecdotal narratives - and seen a lot of the comparative statistics about both races. I find it fascinating how different people can read the same data and reach different conclusions. And, of course, they disparage the other side and call them and their promoted boat types derogatory names. Just like politics, eh?
    I haven't disparaged any boat type or "the other side".

    I'd be interested in discussing the statistics about Fastnet '79 and Hobart '98, because I can't see how the data from those two races can be used to substantiate the oft-made claim that "modern" boats are unseaworthy compared to old ones, as Marchaj claimed from what I can recall. The very high loss rate of long keelers in '98 (even excluding the old planked boat Winston Churchill) is one example of data that seems to have been ignored by many critics. The heavier boats (such as the double ended long keel heavyweight Miintanta which sank, the S&S 34s and the Cole 43s) had a HIGHER rate of inverting or going well past 100 degrees than the fleet as a whole, and inflicted serious injuries on their crew at a higher rate than that suffered by the fleet as a whole. The experience of '98, and arguably of '79, therefore does not seem to support Marchaj's claim (IIRC) that lighter-style boats were significantly less seaworthy than other types, which leads me to believe that his viewpoint may have been a bit skewed in a way.
    Last edited by Chris249; 08-06-2019 at 06:12 PM.

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    Default Re: C.A Marchaj ?

    Calm down, Chris; I wasn't challenging you. I was referring to the dismissive tone and disparaging names offered in Paul G's post #24.

    There was a very good paper written about this subject using data gleaned from the Fastnet and Hobart diasters some years ago and presented at a SNAME section meeting. The author's conclusions discussed various shortcomings of the boats, but were not as clear-cut old-vs-new as you and Paul seem to be suggesting. You could possibly find this paper with a Google search.
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    Default Re: C.A Marchaj ?

    /\

    I didn't say you were challenging me; I just wanted to make it clear that I wasn't disparaging any boat type or anyone else. Nor did I say there's a clear-cut old-vs-new issue. My point is that there isn't any such clear-cut division between seaworthy older designs and newer unseaworthy designs, as (if I recall correctly) Marchaj inferred. While newer boats may have been inferior in certain respects, their overall record appears to be pretty much as good as the older boats and they arguably have strengths that compensate for their weaknesses. I can't find the paper you refer to, but I've read the ones by Dovell, Renilson and Taylor (which contains significant errors).

    To bring it back to the OP's question, I tend to think that Marchaj may have approached certain aspects of sailing (such as mast/sail interaction and the seaworthiness of IOR boats) with opinions that may have ended up skewing his results. It is of course a known issue with scientists,and the sailor/scientists I have discussed Marchaj's mast/sail interface work with have told me that his experiment was a bit dodgy due to the grossly over-sized and unrealistic masts he used in the tests. Practical experience and more recent experiments have shown that Marchaj was wrong in this respect, and therefore other aspects of his early work may also be open to question.
    Last edited by Chris249; 08-06-2019 at 09:14 PM.

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    Default Re: C.A Marchaj ?

    When I wrote the OP, I wasn't aware of any of the author's writing besides the 'theory and practice' tome, which I must say is a dense read, even with a somewhat rusty 45 year old BA in physics. So thank you all for bringing up some of his other work, I will seek it out. The question of survivability of different boats from different times in design thinking is near to my interest: The double-ended Mackinaw boat was apparently favored for it's seaworthiness despite being an open, ballasted boat. I am hedging my bets with buoyancy chambers and excellent design assistance from N.A. David Wyman.
    Thanks to all!
    Ken

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    Default Re: C.A Marchaj ?

    amex_large.jpg

    (Romanelli in 1993 with the 1979 MiniTransat sailboat winner [Norton Smith])

    http://www.histoiredeshalfs.com/Hist...20Minis/49.htm

    1979, The Forgotten Factor, CA Marchaj in memoriam

    IOR-1979.gif
    Attached Images Attached Images

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    Default Re: C.A Marchaj ?

    Marchaj's mistake was to call sailboats that were heavy (=> 200 D / L) "light" (< 150 D / L)

    But Marchaj was right: the IOR was the worst sailboat imaginable for sailing in bad weather

    IMO ... the Way is ...

    or a well-balanced surfboard capable of standing still bow to the waves with sea anchor taking the rudder blades out of the water ...

    ... or go back to T. Harrison Butler


    g641202hullform.gif

    (T. Harrison Butler Z4)


    The problem with modern surfboards is that if stay still with bad sea ... capsize

    This espectacular surfboard, this IMOCA, was broken and had to stop ... and overturned

    once again CA. Marchaj was right

    these surfboards have to stay moving, there is no way to stop them safely


  35. #35
    Join Date
    Oct 2018
    Location
    Vigo, Galicia, Spain
    Posts
    245

    Default Re: C.A Marchaj ?

    083_Gallery_Captioned.jpg

    Robert Manry

    IMO ... the Way is ...

    or a well-balanced surfboard capable of standing still bow to the waves with sea anchor taking the rudder blades out of the water ...

    ... or go back to T. Harrison Butler

    the funny thing is that an IMOCA can take the rudder blades out of the water

    a 5 million euro boat ... and just needed a canvas sack and a rope ... to stand still safely

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