Modernizing Classics, Efficient Long Keels but reduce draft?

Discussion in 'Sailboats' started by CloudDiver, Apr 12, 2017.

  1. CloudDiver
    Joined: Jun 2014
    Posts: 112
    Likes: 5, Points: 18, Legacy Rep: 40
    Location: San Diego

    CloudDiver Senior Member

    Hi everyone... I've been absent on the forum the last 18 months. Finishing grad school and restoring my little 'vintage' swing-keel sloop, both should be done in June.

    I've learned a ton from this forum and done further reading to understand design more, so thanks to the resident experts here for all you share. I do realize there is a ton more I need to, and want to, understand.

    To the question, and its somewhat broad... Modernizing classic designs for greater efficiency, primarily the keel. I'm mostly interested in designs to the Universal Rule, I just can't shake my admiration for the sweeping fore and aft overhangs.
    The designs were heavy timber construction and deep, full keels. Modern construction methods have many examples built in aluminum (all the new J Class, or most?) carbon fiber, GRP, and epoxy cold molded. The J's have to stick with the full keel, but other designers have used modified long keels, fin keels, deep fin/bulb, and lifting fin/bulb.
    I understand that the modern methods and lighter/stronger materials are decreasing overall displacement, lowering weight aloft dramatically, reducing wetted surface area, etc.

    Example 1, Firefly. Built with a deep fin/bulb rudder but designed to have the option of lifting fin/bulb. As beautiful as she is expensive;
    http://claasenshipyards.com/yacht/firefly/

    Example 2, Tempus Class, 90, 125, &150. They speak for themselves, and use various keel configurations;
    http://www.tempusclass.com/

    Example 3, Johan Anker 434. Not built to Universal Rule but a 12 Meter built to the International Rule, still equally stunning. This boat is built (mostly) to the original design with the full keel but it is the stainless steel frames mixed with laminated frames that is remarkable. If I am ever able to recreate a classic design this is the method I would use.
    http://yard.robbeberking.com/anker/index.php

    I used to be obsessed with lifting keels and I have looked at all manner of swing or keel/centerboard designs. My overall goal is to reduce draft but try to retain performance, safety, reliability (mechanically), pointing, etc. I have definitely learned from this forum is that there is always compromise. I almost gave up on the idea that a long keel design could not be modernized without giving up some major concessions. Then I discovered the Bill Tripp designed Columbia 50. That 50 footer has a modified long keel and a deep foil rudder while drafting 6.5 ft (if I recall correctly).

    A particular design I have in mind is a 60 ft LOA, 40 ft LWL, 12 ft beam, 8 ft draft built to the Universal Rule. Ultimately what I hope to accomplish is to retain the breathtaking lines of this design but reduce it's draft while improving its slipperiness. These are the assumptions I am working from;
    1. Epoxy cold molded construction will significantly reduce displacement vs the original plank on frame method.
    2. Even if designing for an aluminum spar and not going so far as carbon is significant reduction in weight aloft and improved righting moment. Add to this a weight savings in rigging with Dyneema.
    3. The original keel ballast was cast iron... With the reductions listed above, and even possibly reducing sail area to boot, ballast weight required should be less. Using lead vice iron results in a physically smaller ballast for the same mass.

    My understanding of NACA foils and generating lift in keel design is rudimentary at best, but basically "I get it". That said, with all the above assumptions in play, can the underwater profile of the hull be improved and the long keel design retained but also improved while slightly reducing draft? I'm not trying to turn an 8 ft draft into a 4.5 ft shoal keel, but I was hoping to retain the benefits of a deep bilge (for things liking sticking the diesel down into) but raising the draft to a more palatable 6.5 feet.

    I know many will ask what the purpose of this design would be... easiest answer, cruiser/racer. I don't expect to beat everyone, but it would be nice to be competitive in a Transpac. I don't want the potential maintenance issues of a lifting keel/swing/CB and want to retain the ability of a long keel to take a grounding. All that said, it'd be nice to bring the draft up from 8 ft to around 6, but I'm not shooting for less than 5. Thoughts?
     
  2. PAR
    Joined: Nov 2003
    Posts: 18,071
    Likes: 355, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    If the aesthetic is all you're concerned about you should consider a replication of these old UR designs. The modifications you're proposing just isn't practical on these hull forms, because of their "built down" garboards and bilges. The W class (> http://www.w-class.com/classic_wooden_yachts/f/PDF/W76.pdf <) by Joel White takes these turn of the century thoroughbreds and makes them considerably better with modern appendages, rigs and accommodations, without sacrificing their classic beauty. Essentially, he cut off the built down sections, removing considerably wetted area and drag, then placed a fin and spade under them and also dramatically improved their ballast ratios. Major surgery for sure and the purests can be pissy, but they still have their souls.
     
  3. CloudDiver
    Joined: Jun 2014
    Posts: 112
    Likes: 5, Points: 18, Legacy Rep: 40
    Location: San Diego

    CloudDiver Senior Member

    PAR, thanks for the link to the W Class... I had seen them before and probably should have included them in my examples above of modernized classics, akin to what Spirit Yachts and Fairlie do as well.

    So essentially there is no way to modernize and improve performance of a long keel without changing it completely into a fin keel with a rounded bilge? I thought it might be possible t make it 'skinnier' but I can also see how tight the bilge and turn in the garboards would become, not to mention how difficult or impossible it may be to shape into anything like a NACA profile along its chord length.
    I have requested the drawings of the hull I am interested in from the Mystic Museum. Hopefully over the next year (or two) I'll be able to successfully render the design in 3D. I like to a version in original 'as drawn' and then do a hull form without the keel so I can experiment with adding keel appendages and see how they perform on paper.

     
  4. CloudDiver
    Joined: Jun 2014
    Posts: 112
    Likes: 5, Points: 18, Legacy Rep: 40
    Location: San Diego

    CloudDiver Senior Member

  5. PAR
    Joined: Nov 2003
    Posts: 18,071
    Likes: 355, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I made a change like this many years ago on a smaller class racer, with the typical long overhangs and built down bilge. The bottom of the boat was literally replaced. The frames cut and reshaped to remove the large "fairbody" and a new foil shaped fin and skeg hung spade rudder installed. The boat needed to have it's laid deck replaced with plywood and it's wooden rig replaced with an aluminum stick, just to save enough weight to make the dramatic reduction in wetted area viable with the SA/WS and ballast ratio changes. The boat accelerated faster, but was a bit more tender. She was more maneuverable, but her roll moment was harsher and she needed to be reefed much sooner. For the effort, it wasn't worth it in terms of the resulting performance envelop changes. For the client, it worked out, as the once leaky, worn out boat was now better equipped for dry storage and considerably stiffer structurally. It would nearly have been cheaper to build a new hull, in hindsight.
     
  6. philSweet
    Joined: May 2008
    Posts: 1,993
    Likes: 92, Points: 48, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    The most important drivers of keel area and draft are the minimum sailing speed, the need to maneuver under sail only, and the sail area and height of the rig. If you take a stock old boat like the Larchmont O class, add a decent little diesel (which you are prepared to use at low speeds), and add a small bow thruster, you could reduce the keel area without any appreciable loss in sailing performance above, say, 3.5 knots. Reducing draft is trickier, and figuring out if, and how much, you can reduce draft is going to need fairly sophisticated modelling. Induced drag is very sensitive to draft, and it is also a large component of drag when pointing. If you can make the rig and controls more efficient, you can trade off a bit of hydro drag. This may seem easy enough, but those boats had a large crew of very talented sailors, and just matching their sail handling ability is going to be a real trick. A rig for a 60'er designed for couple sailing might be more efficient on paper, but it will sacrifice some of it's potential in the name of handling ease. So it comes down to tradeoffs, with the draft issue being very important to the goal of "matching the pointing" of the older boats, and probably something that gets finalized towards the end of the design spiral.

    [​IMG]

    http://sailboatdata.com/viewrecord.asp?class_id=7699

    from http://classicsailboats.org/the-larchmont-os/
     
    Last edited: Apr 16, 2017
  7. CloudDiver
    Joined: Jun 2014
    Posts: 112
    Likes: 5, Points: 18, Legacy Rep: 40
    Location: San Diego

    CloudDiver Senior Member

    @philSweet, did you know, or was it cosmic chance, that the Larchmont O class is exactly the boat I was talking about? BTW, this hull is (at least by one account) the first racing hull fit with a Marconi Rig, although it was designed as a Gaff Rigger. Only one of the six hulls built had the Marconi.
     
  8. philSweet
    Joined: May 2008
    Posts: 1,993
    Likes: 92, Points: 48, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    Cosmic chance and a peculiar head for boat specs.
     
  9. Doug Lord
    Joined: May 2009
    Posts: 13,880
    Likes: 118, Points: 73, Legacy Rep: 1362
    Location: Cocoa Beach, Florida

    Doug Lord Flight Ready

    Georgia

    My Dads Larchmont "O" boat Georgia. He would have probably not "modernized" her one bit. He owned the boat in the late 40's. He fell in love with the W class boats when they were first out a few years ago before he passed away:

    [​IMG]


    Georgia on the cover of Yachting, 1951-Dad is the man in white:

    [​IMG]
     
  10. CT249
    Joined: May 2003
    Posts: 852
    Likes: 24, Points: 18, Legacy Rep: 215
    Location: Sydney Australia

    CT249 Senior Member

    The winner of the first Seawanhaka Cup, Ethelwynn, also had a marconi and that was in the 1890s. Some sources indicate that Six Metres had a marconi before the O Class, and it appears that a 15 Metre designed by Nicholson did too.
     
  11. CloudDiver
    Joined: Jun 2014
    Posts: 112
    Likes: 5, Points: 18, Legacy Rep: 40
    Location: San Diego

    CloudDiver Senior Member

    That's so awesome to hear... I'm assuming that you had a chance to sail on her? Do you know what happened to the hull? Its so depressing that none of the original six (or even any reproductions) exist. If I even had a clue as to where any of the bones may be lying in reasonable structural condition I would make a summer vacation adventure out of finding it and photographing every square inch, maybe even scanning if I could borrow some portable equipment. Now where did I leave my fedora?

    You make an excellent point from your father's opinion... other than modern materials and building techniques I'm thinking I wouldn't modernize much either, 8 foot draft and all. I believe the original lines would be not only beautiful, but even quite competitive in spirit of tradition regattas.
    For myself, one life goal is the Transpac. I would prefer to do it on a hull with character and grace.


     
  12. CloudDiver
    Joined: Jun 2014
    Posts: 112
    Likes: 5, Points: 18, Legacy Rep: 40
    Location: San Diego

    CloudDiver Senior Member

    These are my sources below and there are very few, although I have no doubt they are not necessarily gospel. The line says "VARUNA was the first yacht fitted out with the innovative and controversial Marconi rig.(est 1917-18)" The wording of that statement is subject to a great deal of interpretation.

    http://classicsailboats.org/the-larchmont-os/
    http://classicsailboats.org/portfolio-view/william-gardner-georgia/

    I don't doubt that there were others with Marconi Rigs pre turn of century. Its funny because I had just come across numerous drawings of that era that had fin/bulb keels and spade rudders, something I previously thought was not of that era.
     
  13. Doug Lord
    Joined: May 2009
    Posts: 13,880
    Likes: 118, Points: 73, Legacy Rep: 1362
    Location: Cocoa Beach, Florida

    Doug Lord Flight Ready

    --------------------------
    I never had the pleasure to sail on Georgia-I was but a gleam in my Fathers eye at that point. But I have many pictures of the boat and the memories of the great stories about Dad and Mom and their friends. Dad loved to race and he scared the hell out of Mom and others cutting it very close at times. He must have had great fun! He sailed the boat for a year or two with no engine! He wouldn't have changed Georgia for anything but,at the same time, later in his life he really liked what Joel White did with the W.

    From Dads picture:UPDATE-sorry to say it looks like the camera ,somehow, distorted this picture with slightly more sweep to the sheer line than is actually there. Actually, the whole boat is distorted-just noticed it and put a straight edge on the image here and the actual image and the waterline is curved on this image. Sorry.....

    [​IMG]
     
    Last edited: Apr 16, 2017
  14. NoEyeDeer
    Joined: Jun 2010
    Posts: 977
    Likes: 29, Points: 0, Legacy Rep: 300
    Location: Australia

    NoEyeDeer Senior Member

    One thing you may not have considered: if you change a full keel hull to have a tighter garboard radius, this will increase the hull's wetted surface due to the increased girth measurement around the more extreme curve.

    Increased wetted surface will, of course be detrimental to performance.
     

  15. DCockey
    Joined: Oct 2009
    Posts: 3,717
    Likes: 120, Points: 63, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    Stephens Waring Yacht Design specializes in "Spirit of Tradition" yachts, ie yachts with a combination of traditional aesthetics and modern performance. http://stephenswaring.com/

    Several posts in the News section of their website discuss what Spirit of Tradition means including:

    THE 8 RULES OF SPIRIT OF TRADITION YACHT DESIGN http://stephenswaring.com/the-8-rules-of-spirit-of-tradition-yacht-design/

    A SPIRIT OF TRADITION CLASS MANIFESTO http://stephenswaring.com/a-spirit-of-tradition-racing-manifesto/

    THE SOT REGATTA DEBATE GOES GLOBAL http://stephenswaring.com/the-sot-regatta-debate-goes-global/
     
Loading...
Similar Threads
  1. Moggy
    Replies:
    3
    Views:
    1,246
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.