Principles of Yacht Design, Fourth Edition

Discussion in 'Boat Design' started by DCockey, Apr 3, 2014.

  1. DCockey
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    DCockey Senior Member

    Principles of Yacht Design is frequently recommended here as a good text and reference for boat design. It has been revised as a Fourth Edition with another co-author added, Michal Orych. Dan Spurr reviewed it in the April/May 2014 issue of Professional BoatBuilder but doesn't say much about the actual content, more of a very brief summary than a review. Spurr does comment that
    the authors state that "yacht design is by its nature a quantitative process," not qualitative, and the designer needs to know , "as exactly as possible, is the minimum skin thickness and the least amount of lead needed in the keel for the yacht to be safe under all possible conditions".​
    This is an interesting statement. I'm not sure the minimum skin thickness and least amount of lead in the keel necessary always needs to be known as "exactly as possible". Certainly those would be a major consideration for a boat where performance is a major consideration but for other boats knowing that the hull thickness and amount of lead in the keel are adequate may be sufficient. Also yacht design is both qualitative and quantitative, and it is important to recognize that many of the formulas and criteria used while very useful do not represent the reality of a boat in the water and wind in an exact manner.

    I look forward to looking through the Fourth Edition when the opportunity presents itself, but at this time I'm not planning to replace my copy of the Third Edition.
     
  2. Olav
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    Olav naval architect

    Yes, I tend to second that. If you are after a high-performance design it's obvious you want to keep the structure to a minimum to save weight - but even when performance is not the most important factor (i.e. a cruiser design) you can save money on materials and labour if you don't overbuild things. Of course there's some cross-over point where the increased effort in more careful and extensive engineering (contrary to some quick rule-of-thumb scantlings) outweighs the savings on material and building time.

    Again I mostly agree. Whether you are more interested in qualitative or quantitative results depends on the task you are performing: With a conventional design the focus will be more on the qualitative side - there's no need to understand what's exactly happening in terms of hydrodynamics, mechanical stresses and the like. When designing something new or with the intend of an improvement over existing boats you won't get around the need for deeper insight and understanding of the physics. A pure researcher may well be mostly interested in qualitative stuff only.
     
  3. Ad Hoc
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    Ad Hoc Naval Architect

    Not having read the book nor know much about the author, this could be read one of two ways.

    1) Exactly ...here is perhaps being used more of a must be to try and establish as much as possible rather than simply just guessing.

    2) As you have and Olav have both noted.

    If 1), it is an odd way to phrase such and important feature of design...hence my caveat, not knowing much about the author, nor their experience.

    However I do tend to side with both of you...since very little is "exactly" known in designing vessels. Even the lightship via an inclining is subject to many systematic errors, thus is never exact! It is all about trends, not absolutes.
     
  4. Remmlinger
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    Remmlinger engineer

    Thanks David for the hints.
    Since I am still working with the first edition, I am asking myself whether I should get the new book, but I am hesitating.
    The designer of the new YD 41 is Michal Orych (see http://publications.lib.chalmers.se/publication/190934-principles-of-yacht-design-4th-ed)
    who is a PhD student and a project manager at Flowtech. This company is a spin-off of Chalmers University and markets the CFD-Code Shipflow. To teach me yacht design I would rather prefer a N.A. who has successfully sold his designs and got feedback from his clients.
    What puzzles me is the fact that the book obviously still relies on the Delft tank test results (they thank Lex Keuning) even though The CFD-code Shipflow claims to make the work at Delft obsolete.
    Another fact that I do not like is the replacement of the ABS-scantling rules by the new ISO-standards. I had a frustrating e-mail exchange with Gregiore Dolto some time ago. I got the impression that this is a panel of bureaucrats who have never taken the responsibility for the delivery of a yacht.
    I will buy it if somebody can show me that I am wrong.
    Uli
     
  5. Rastapop
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    Rastapop Naval Architect

    For anyone interested in the author, here is a bit of background:
    http://www.chalmers.se/en/staff/Pages/lars-larsson.aspx
     
  6. Richard Woods
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    Richard Woods Woods Designs

    To set the record straight

    Gregoire is a French yacht designer, part of the Graal group and responsible for the design of many boats, power/sail, monohull and multihull, cruising and racing.

    I do not know exactly who is on the ISO scantling committee, but I have served with Gregoire on the ISO Stability and Buoyancy for over 20 years under convenor Andrew Blyth (who is also a member of this forum).

    Far from being a "panel of bureaucrats" the committee I am on consists in the main of practising yacht designers. Obviously members come and go, so I think Bob Johnson of Island Packet yachts who served for years has now retired. But others on the committee now include French multihull designer Erik Lerouge, Peter van Oossanen, and of course Rolf Eliasson. Only Rolf, Gregoire, Andrew and myself have been members since 1991.

    Rolf is a very well known and respected award winning designer of both sailing and power boats and is also a cruising sailor who has lived on board his own designed boats for years. He and I were in the same marina in Panama a few years ago.

    Obviously as a new edition it is based on the previous books, it isn't a complete re-write. But there is now much more about powerboats than there was in earlier editions

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  7. Ike
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    Ike Senior Member

    Well Said Richard. Unfortunately many people who have no knowledge of the process for setting standards think that they are all done by bureaucrats. The truth is they are all done by volunteers mainly from the industry involved, with an occasional government employee from the agency that is involved with the boating industry such as the US Coast Guard, or the Maritime and Coast Guard Agency. As a Coast Guard employee I was the only bureaucrat on many committees for ABYC and SAE, but all of the other members were people from the industry, builders and surveyors, manufacturers of marine equipment, etc. ABYC has representatives on many of the ISO committees, and the make up of these is pretty much the same, all volunteers. There is a lot of crossover between ISO, ABYC, SAE, NFPA and other standards organizations. Thanks for setting the record straight
     
  8. Rastapop
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    Rastapop Naval Architect

    Correct me if I'm wrong, but haven't the ABS standards for yachts remained unchanged since 1994, while ISO 12215 was updated as recently as 2012?
     
  9. FAST FRED
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    FAST FRED Senior Member

    Most materials slowly wear , depending on load and encountered cycles.

    Thinner, lighter WEAKER ,(long term) may be fine for the racers that can scrap the boat after a couple of years , but for cruisers?

    Most of the early GRP boats were >overbuilt< by todays standards , but they're not scrap, they are still sailing!
     
  10. MikeJohns
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    MikeJohns Senior Member

    Precisely;)

    ISO 12215 is continually corrected and updated.

    ABS ORY was a bit hit and miss for composite construction. The 1986 version was deficient in its keel-hull attachment loading and had a woefully inadequate laminate schedule in that area. The 1994 version was corrected for keel loading but was still deficient in the fore deck design pressure. That has not been corrected, instead ISO 12215 was adopted as it's replacement.
     
  11. fcfc
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    fcfc Senior Member

    The intended public of the book is mostly beginners and individuals. Any spreadsheet is way more accessible and usable for them than Shipflow.
     
  12. Rastapop
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    Rastapop Naval Architect

    ?
    Maybe I'm the only one with this opinion, but (depending on what you meant exactly) I don't think beginners who need a spreadsheet instead of CFD are likely to attempt to design a yacht....
     
  13. TANSL
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    TANSL Senior Member

    Unfortunately I fear, and is just an opinion, that many "designers" with knowledge of naval architecture of a beginner, have used this book to "design" boats.
    I do not judge whether this is good or bad, just saying that it is likely that this has occurred.
    I must also say that this is a useful book even for highly skilled designers. Do not get me wrong.
     
  14. DCockey
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    DCockey Senior Member

    Who has claimed that Shipflow CFD makes the Delft series work obsolete? The discussion of CFD in the Third Edition of Principles of Yacht Design compares CFD to tow tank testing, not regression series. It says "Therefore, CFD at the present is a tool to be used when optimizing a design. Absolute accuracy s then not necessary, but the method must be able to rank alternatives in the right order. Furthermore, the detailed flow information may guide the designer in the search for a better alternative."

    Good CFD codes do not make good regression models based on experimental test series such as the Delft series obsolete. Both have their uses. Regression models can provide very useful performance predictions and are a valuable tool for making decisions during the preliminary design phase if used within their range of validity. Of course that is a big "if" since there can be a strong temptation to push the applicability range of any model. CFD is also a very useful tool but one that takes considerably more time to prepare the input for than a regression model. CFD also requires care and knowledge to interpret the results and to separate numerical effects and artifacts from physics. The ability to prepare input, run the code, and create nice graphics based on the results does not guarantee that the results are physically meaningful or their interpretation correct.

    An efficient design process starts by using knowledge from previous designs and applicable regression models. Then, if needed, CFD and other advanced numerical analysis methods are used where the available information is insufficient or not available.
     

  15. Remmlinger
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    Remmlinger engineer

    I am sorry if my post has upset someone. I do not know the people on the committee, so thank you for some explanations. I should not have used the word "bureaucrats" that just raises unnecessarily the blood pressure. In my post I was referring explicitly to an e-mail exchange with Mr. Dolto about ISO 12215-9. He told me that he is not interested in experimental or scientific results. His only intention was to cast a ballot among the committee members and get the majority of votes as soon as possible. This shocked me. I am an engineer for 37 years now and I was responsible for the design of many safety relevant products that are sold all over the world. The most important part of the R&D process is the description of all relevant load cases and these design loads have to be verified by measurements in the real environment. In the mentioned ISO standard there is no reference at all about the origin of the assumptions that make up the load cases. A static 90 degrees heel is by no means the most severe load for the keel. I wish there were more transparency in the process, visible to the end user. There should also be references to publications in the open literature that report about the measured stresses that were used to define the design loads.
    Uli
     
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