Offshore ability of sharpie design?

Discussion in 'Sailboats' started by Seafarer24, Mar 24, 2008.

  1. Seafarer24
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    Seafarer24 Sunset Chaser

    I've inspected and been somewhat disappointed with the 37' Sharpie/Dory in my previous post. Not the design, so much as the condition of the vessel. However, it still has some very useful parts that may be worth the cost of the boat. Namely, the rig. Twin 25' freestanding fiberglass masts with gaff-rigged sails. I'm trying to get in contact with the owner (whom has proved surprisingly elusive for someone who has been trying to sell his boat for years!) to find out the exact sail area.

    I am considering building another boat and transplanting this rig onto that hull. At least, a version of this rig that retains the masts. Possibly junk sails, or a combination of a gunter and (psuedo) gaff to haul up more sail area. The design I'm considering is Parker's 39.5' "Snowy Egret".
    [​IMG]

    I've heard that sharpies can hold their own off-shore. Are they considered seaworthy in an ocean-crossing context, or are they strictly near-coastal craft?

    I'm not entirely sold on the dory "pinkie" stern over a more squared-off stern. The argument is that it adds to seaworthiness by parting any waves coming from astern. I believe a higher-volume stern would more readily lift to those waves, and certainly improve the speed of the boat. I know that's not a new debate by any means....
     
  2. sharpii2
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    sharpii2 Senior Member

    No, They are typically not sea faring craft. Even The EGRET type was only stable to about 90 degrees.

    That is considerably better than the typical sharpie and at a considerable cost to performance, but it is not good enough for secure off shore work.

    This is, of course, with relatively low sides and internal ballast.

    With an external ballast fin keel, the sharpie could become a whole different kind of boat.

    It's stability range could be widened considerably to perhaps 125 degrees, while maintaining much of its performance. But would it then really be a sharpie?

    If you look at a lot of very fast ocean racing monohulls, you will see a striking resemblance to the boat I just described, with only the side corners rounded off.

    I personally have a concept I have been kicking around for years. It is a high side, double ended, internal ballasted, "V" bottomed sharpie. It ended up with a range of stability calculated to be about 141 degrees.

    All of which is good.

    The bad part is that its sail carrying ability got reduced quite drastically and it would have ended up to be quite a slow boat. Since sea worthiness and low cost, not speed, were the major objectives, I was satisfied with the result. I now have a design that can use non metal ballast and still be arguably safe to go off shore in.

    If this is close to what you are looking for, just keep in mind that the hull depth/Beam ratio must be kept relatively high. I would say at least 50%. My concept has a Hull depth/Beam ratio of nearly 60%, but much of that is for accommodation space. With a lower hd/b ratio, be prepared to use denser ballast and more of it. you may end up needing as much as 50% ballast. My concept would be able to get by with slightly more than half that much.

    Also, keep in mind, that for off shore work, a boat's upside down stability is as important as its right side up. It is for this reason, a pointed stern boat may end up with a greater range of stability than a squared of stern one for the same hd/b and ballast /displacement ratio.
     
  3. Seafarer24
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    Seafarer24 Sunset Chaser

    Ah, damn.
     
  4. alan white
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    alan white Senior Member

    The Seabird yawl (Thomas Day) had a lot of sharpie in her. Though the original centerboard design crossed the Atlantic, it was an enlarged version (35 ft I think) that was made into a true offshore cruiser, with the addition of a full keel. No longer a true sharpie.
    The original centerboard Seabird was a seaworthy boat, very bouyant and in fact designed to survive being knocked down or being partially submerged, with a small self-bailing cockpit and a well-crowned cabin (though a more moden version would have more freeboard, similar to the Norwalk Island Sharpie designs).
    Phil Bolger, marine architect, would argue that the sharpie could be made seaworthy by several design features such as ample freeboard, a high-crowned cabin top to promote inverted instability, and even enough flotation to float the water-filled boat.
    To some, a lighter-than-water structure is inherently a superior survivor than a far heavier keel boat. Multihull adherents use this argument all the time, citing examples of sailors who lived inverted awaiting rescue for weeks ion their cats or tris.

    Alan
     
  5. sharpii2
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    sharpii2 Senior Member

    I have also heard of accounts of inverted multis where the crew is never seen or heard from again. But I would not let that stop me from sailing a conservatively designed multi across an ocean. Unlike a conventional sharpie, a good multi is far less likely to capsize.
     
  6. alan white
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    alan white Senior Member

    Sharpie types have crossed oceans, but of course any boat will go offshore if properly set up. Then they will self-right, which is impossible for a multi(except if a giant wave is around to help out).
    So Day converted the centerboard to a full keel... for room inside, and not necessarily for safety (I seem to recall readung he was unhappy with the full keel because it ruined those qualities of motion that made the centerboarder so handy).
    Any case, Phil Bolger would agree I think, and go on to prove it. Personally, I like the idea of an bouyant and unsinkable hull (possible with Norwalk Island sharpies, St Pierre dories, Seabirds, and many others) because they are far more accessible owing to lower cost per foot.
    A great mass of ballast requires a lot of structure, since that mass doesn't yield so easily to wave motion, while a far lighter hull simply moves aside.
    Multihulls prove this out--- they are ultralight even compared to centerboarders. Comfort is another issue, of course. You want height inside and the trunk is in the way too. Leeboards?

    A.
     
  7. Seafarer24
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    Seafarer24 Sunset Chaser

    Did any of you actually click on the picture and view the plans for that boat? I think they did an excellent job of interior layout compensating for the CB trunk. If it has standing headroom (6'), that's a hell of a nice design.
     
  8. sharpii2
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    sharpii2 Senior Member

    I think the much maligned 'McGregor 26', with a 9 hp kicker instead of a 50 hp brute Ob, could be a modern example of this concept.

    But I do think we need to be more honest about this.
    [/COLOR]
     
  9. Seafarer24
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    Seafarer24 Sunset Chaser

    How about a pulling an inflated "baloon" (think racing mark) to the top of the mast. When inverted, this would raise the mast to ~horizontal, where a ballasted centerboard in the extended position should be able to bring the hull back upright.

    Alternatively, you could just have aerodynamically-shaped floats at the top of the mast, as the Iroquis catamarans did.
     
  10. mizzenman
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    mizzenman Junior Member

    what if the mast breaks?
     
  11. sharpii2
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    sharpii2 Senior Member

    sharpieoid design drw

    Here's a crude drawing of the 'sharpieoid' design concept of mine I have mentioned in previous posts on this thread.

    The fixed lee board like keels were intended to serve two purposes:

    1.) to keep all the fasteners above the static water line and

    2.) to maximize the buoyancy shift by the keels as the boat heels.

    To me, the design, though odd, seams stronger than the twin bilge keels that are the logical alternative.

    The great size of the 'V', in the cross section, is intended to keep the upward bends (rise) of the chine logs to a minimum. In the stern, they do not rise at all.

    This was all to simplify construction.
     

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  12. Gilbert
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    Gilbert Senior Member

    "The Good Little Ship" by Vincent Gilpin is a great little book expounding the virtues of the PRESTO style boats developed by Ralph Munroe.
    Francis Kinney has drawings of ENDEAVOR in his update of 'Skene's Elements of Yacht Design".
    I have seen many pictures of Crocker designs that were based on this type of boat that were considered to be great boats also.
     
  13. alan white
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    alan white Senior Member

    Recently I looked into Bolger's Black Skimmer design. Leeboards, 8 knots saling speeds, points in 80 degrees, freestanding yawl rig, very light and stiff 25 x 7 ft boat. No headroom whatsoever. Will sleep two comfortably though.
    Stretched to 32 ft or so you might get headroom and offshore capability.
    And of course it's unsinkable.

    Alan
     
  14. kengrome
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    kengrome Senior Member

    Hi Alan,

    Now that Jeff Gilbert has designed a self-righting catamaran (What's that you say ... a self-righting catamaran???) it seems the world is going to have to get used to the concept of self-righting multihulls.

    :)


    [​IMG]


    There are three more drawings of this boat (the Derby Gravel Truck) in my gallery, and I think this is the URL to my gallery:

    http://www.boatdesign.net/gallery/showgallery.php/cat/500/ppuser/15501
     

  15. alan white
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    alan white Senior Member

    Motor cat. Could a sailing cat do the same?

    A.
     
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