Sharpie redesign assistance please.

Discussion in 'Boat Design' started by dirtybeard, Jun 10, 2007.

  1. dirtybeard
    Joined: Jul 2003
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    Location: Olympia WA

    dirtybeard Junior Member

    I recently obtained a 26foot sharpie, T. Colvin design which is apparently a cross between a New Haven (round stern) and a wider, chesapeake flattie style. It is 7.6 beam on deck. Breadth on the bottom is 5' 4 inches. It has a 12 inch skeg.

    It also has a very large centerboard and 300 pounds of interior lead ballast. The centerboard totally splits the cabin area longitudinally.

    Currently it is gaff rigged.

    It also has extensive deck rot, but the boat was built in Bellingham WA state where they made the hull quite robust and so far no sign of rot below the deck knees.

    Suffice it to say that the deck and cabin must be removed and destroyed. Can't believe they were built of marine grade plywood.

    So, I need a redesign of the sharpie interior. I intend to remove the centerboard, and replace it with lee boards. This will free up the interior space for a total redesign.

    I intend to reinforce the bottom of the hull for the harder landings that I will be making in my south puget sound gunkholing with the boat when done.

    The goal is a self-righting pocket cruiser with trailer/beaching capabilities. Rigged with fully battened lug sails (chinese style) and lee boards should be easier handling, and ability to run up on our gravely beaches here.

    So the need is to raise the freeboard once the deck/cabin is gone. Replace the centerboard with a water tight seal. Then what?

    How to lay out for a party of two with a couple of big *** dogs and week long treks?

    I was hoping for a Bolger style sort of with as much full head room as possible. And hoped to build it with a cabin roof deck stucture capable of handling the walking around.

    Now, it has a round stern, very voluminous, I hate loosing all that space under this currently badly placed and badly designed cockpit. I think to also raise the stern by same amount as the rest of the freeboard, increasing the stern size but how to design a good alternative to the 'regular' sealed hole cockpit things. Any thoughts?

    Any guidence would be appreciated. I have nearly all the tools a fellow might need, and some considerable skill in wood, welding and other such boat building arts, and am prepared to tackle the work. But need a few ideas please that will go toward stability and self righting and such comfort as may be obtained in such a small boat.

    Thanks. Yep. long winded *******.
     
  2. messabout
    Joined: Jan 2006
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    messabout Senior Member

    Study the Bolger Black Skimmer design. It has lee boards, is about the same size. You will find some odd features incorporated in the Skimmer. When I first laid eyes on a B.Skimmer, I thought, "that Bolger dude is a really weird". Then I spent several days cruising around on it. I am here to tell you that every feature of the boat was absolutely functional. That includes free flooded compartments at both ends of the boat, offset mizzen, goose winging lee boards, etc...
    The rig is sprit boom yawl type and for practicality and ease of handling, there are few if any equals. Bolger is boatings' guru of common sense even if some of the stuff seems odd.

    He also has a design that he called Big and Tall. It is a cabin layout that is fairly spacious, airy, and is not so high as to create excess top hamper. That one is worth looking at too. There would be room for a couple of friendly people and two big assed dogs inside the cabin when bad weather arrives. If I recall the mainmast was in a tabernacle for easy ducking under bridges, hiding from the law and so on.
     
  3. Mark Van
    Joined: Jul 2002
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    Mark Van Junior Member

    My Dad built the larger versoion of that sharpie in 1982. He put the centerboard off to one side, using it as the front of the galley. It really opens up the interior. There is no way to get standing headroom in a 26 foot sharpie without ruining it for sailing. It is a very nice looking boat built as designed, and I don't think re-designing it from the deck up will improve it. You will probably just end up with an ugly boat that doesn't sail well, instead of a pretty boat that sails well.
     
  4. dirtybeard
    Joined: Jul 2003
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    Location: Olympia WA

    dirtybeard Junior Member

    Thanks.

    Admitedly a pretty boat. But the deck is rotten, as is the cabin sides, and the cabin top is probably not even marine grade ply.

    In any event, I prefer lees over center no matter the placement for my specific purposes with this boat.

    If my redesigns take an edge off the sailing but I end up with a self righting, anti-capsizeable, easily handled vessel that doesn't point quite as well, then fine. The use I have for it, it need not be the most skookum boat around.

    However, having seen the bolger designs, and read monroe's critic of the sharpies of the time, more freeboard and less traditional looking don't necessarily mean ugly, nor inefficient for the purpose.

    Now every thing on this sharpie is designed to suit the naval architect's idea of 'serving the boat'. I am a human, and wish the boat to serve me.

    Really like the thinking that comes out of people like B. Fuller, and Bolger. Open minds are required to receive ideas.

    I am trying to scrounge up the lexan needed to raise the freeboard bolger style and let in max light. I will have more of a rigid cabin top/deck than usual on the bolgers as the hull of this sharpie is very heavily built to take our tempremental conditions here in Puget Sound. Lots of pounding in the straits, so this hull is thick, and well ribbed. That will provide a heavier than usual sharpie hull for my intended pocket cruiser.

    And you can get adequate head room in a 26 foot sharpie with merely a bit of creativity.

    Thanks for the suggestions, now where can a guy find this Big and Tall info?

    dirtybeard old fart.
     
  5. dirtybeard
    Joined: Jul 2003
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    dirtybeard Junior Member

    round stern on the sharpie

    the sharpie has a round stern, well made. It has the tiller going through a bit of pipe down to the rudder.

    I am *really not* a fan of through hull anydamnthings.

    I will be following the lines up in raising the freeboard. So then I will end up with a larger round stern.

    Anyone have pointers to outboard, hung rudder/tiller arrangements for a round stern? That could then be adapted to a sharpie?

    And how about suggestions on how to use the space aft?

    Right now the cockpit has this little bit of copper pipe to drain through the centerboard trunk. This kind of crap scares me. I will remove the center board any way, so how about self bailing cockpit in a round stern? any pictures of anything close?

    Thanks.

    Sorry to piss off the traditionalists, but the planet is changing and
    needs must as the devil drives....

    dirtybeard
     
  6. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    A center cockpit allows use of stern space as a second cabin. The cockpit can be 6' 6". The aft cabin makes a double berth with the hatch offset, and a chart table opposite.
    This allows the engine to sit in a proper engine room under the cockpit. Uf ketch rigged, the mizzen is just kissing the forward bulkhead of the aft cabin.
    Wheel steering is necessary, but rudderpost is probably vertical and cable steering quadrant can carry forward to wheel at a height just below the double berth.
    Forward cabin with head, galley, and v-berth/dinette.
    Flush deck is simple and strong, and makes up for lack of standing headroom. Enormous space to each side of engine, 8x8 cockpit, works well with tent because it's between two cabins.
    This is how I've designed my own sharpie, based on a St Pierre dory. All except the engine centered. I am working on putting the engine to one side and using a centerboard. Nothing wrong with leeboards---- I just prefer a centerboard.
    Looks like this:
     

    Attached Files:

  7. alan white
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    alan white Senior Member

    Plan view, quick sketch
     

    Attached Files:

  8. dirtybeard
    Joined: Jul 2003
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    dirtybeard Junior Member

    thanks. Cool layout. I will likely have no internal engine. Many reasons for this. So extra space. I still amazed at the volume below even the very low deck on the critter now.

    Going to 'bolgerize' the boat. The center cockpit idea is pretty good but presents a few challenges that I do not know I wish to undertake, such as self bailing issues.

    At least I am not the only one planning a house in a sharpie.

    I have been in camper trailers with less room on 24 foot than this boat.

    I am trying to raise the money now to buy and end lot of carbon fiber fabric at 9oz that would allow me to wrap the boat from the bottom all the way up the sides and over to nearly mid cabin on my redesigned structure.

    The weight strength ratios for this stuff are equal to 30 oz glass and it has the added advantage of being UV stable...and shiney black naturally so may just not ever paint it. Will have to see.

    Anyway the idea is as unbreakable and uncapsizable, and self-righting in the event of knockdown, and beachable on just terrible rocky beaches as is possible.

    Part way there. Now to start the deconstruction process as well as the major scrounge to get the materials needed.

    thanks for the help. Gets me thinking. Always a dangerous undertaking.

    I will be setting up a page for pictures of the project as it proceeds in case any one wants to watch the horror show...
     
  9. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    I take issue with the "CF is summum bonum fo boat building". Great stuff for all out racers but far out overkill for a cruising boat. Cf has strength to weight ratio that is better than most materials but that is not enough to know. How will the Cf be loaded ? In tension, compression, or bending, or some combination? In bending mode you will not get your moneys worth by a long shot. For a given number of dollars you could make a thicker skin of something cheaper. The thicker skin will withstand bending better than a thin skin of miracle material. Bending strength increases exponentially with thickness and the fourth power of the distance from the neutral axis will outrun the exceptional strength of CF real fast.
     
  10. dirtybeard
    Joined: Jul 2003
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    Location: Olympia WA

    dirtybeard Junior Member

    messr. messabout,
    you are correct. I have researched the stuff once presented with a sample and the literature and have come to the same conclusion. That the depth of the resin+material layer will always favor the thicker layer over the nature of the fiber. So now, whew, will just to a lot of system 3 work with glass cloth.

    now the decisions in with the fiberglass cloth, and the forms of that. I will use a bi/tri axial on inside seams, but on the exterior, is twill weave, or other 'satin' weaves worth the extra bucks?
     
  11. alan white
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    Location: maine

    alan white Senior Member

    I don't know the depth of your hull, but the one drawn isn't much over a foot.
    That would put the bilge height at 24" clear for four feet of width, as the cockpit in my drawing is a full foot above the waterline.
    A sharpie generally has a shallow V bottom, but an engine in the center would probably have 30" height limit with the cokpit sole at a foot above waterline. The coamings in the drawing, which blend into the cabin sides, form seatbacks. The center cockpit is the deepest part of the boat on a dory but a sharpie might have more depth forward (dunno).
    I like the setup because of a center engine room. But your outboard will eat up some aft cabin space, so maybe it won't work for you.
    Keep us posted.

    A.
     
  12. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I've sailed many sharpies, designed several and currently have one going together in your area.

    I designed it for the local waters, currents and general conditions you'll encounter. It's construction reflects the needs typical of that part of the north west (it's stout).

    A self righting sharpie is very difficult to design. Keys to success are sacrificing windward ability, because of the increased windage in the excessive freeboard and cabin arrangements. In other words, the cabin needs to be tall, but with dramatic roof crown, additional freeboard and ridiculously small side decks. This makes her less stable inverted so she'll right herself. This must be coupled with an absurdly heavy bottom and/or ballast, plus a low aspect, light weight rig.

    Leeboards are also difficult to retro fit on a hull. The reason is a leeboard hull usually has it's maximum beam in quite a different location, then desirable for a centerboard craft. Leeboards will not add any additional stability, nor make the craft more shoal. They do bang around annoyingly if poorly arranged, require extra effort in maneuvers and add additional weight above the CG. I've sailed a few small and two different large Herreshoff designs (Meadowlark and Golden Ball) and the Herreshoff boats show exactly why they need to be designed with care, as they performed very well, but were intended from conception as leeboard vessels. The key to these are placement on the hull (location) and the pivot fitting design, which on the Herreshoff's were first class and the others less so.

    Because of the hull shape limitations (forced by the position of the boards), you'll also have rig location requirements that could prove challenging. In other words, you can't just hang leeboards outboard of where you found the centerboard. This requirement alone will likely force you to move the rig aft a considerable amount.

    Before you make too many alterations, you should get the rig and boards balanced on the hull, in a fashion that will provide a reasonable expectation of helm balance.

    I'm not trying to piss on your parade, just a few words of note from someone who's designed and built a few sharpies. For what it's worth, I'd never try to make a sharpie self righting. I have designed them with substantial stability curves, that will tolerate a 90 degree knock down and pop back up, but self righting is altogether different and very difficult in shoal, relatively flat bottomed craft.
     
  13. dirtybeard
    Joined: Jul 2003
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    dirtybeard Junior Member

    A 90 degree knock down and pop right up is what i define as self righting.

    well aware of the limitations imposed in a redesign.


    Centerboards won't work for my application for the boat. In this case the boat is not seaworthy with the centerboard the way it is in any event. And centerboards are a maintenance nightmare.

    I understand and have sailed with leeboards. They can be placed a hell of a lot easier and balanced than centerboards misalligned, and mis sized. I intend to go to fully battened lug rig, aka junk style, with hollow masts as I am an old fart and wrestling trees is not fun. So the rig is changing any way. And the old masts were rotten and cracked. And water logged.

    I will birdsmouth up a nice oval, and have a few ideas about a nifty tabernacle design for ease of handling. I will use bolger style offset masts as well as altering the rudder as part of the whole refit.

    anyway, yep likely will be a *******, but now is merely a death trap.

    Here are pictures as it sits. Demolition is easy as there is considerable deck rot.
    http://www.halfpasthuman.com/sharpie/sharpie1.htm
     

  14. PAR
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    PAR Yacht Designer/Builder

    With the relatively fine entry and max beam location, your boards will be farther aft then the current centerboard location, if optimally arranged for this hull form. This will force the relocation of your CE to maintain a reasonable relationship with her appendages. I'd strongly advise you work out a sail plan, that can balance over those appendage locations, before you get too far into her rebuilding. Another point to ponder, adding mass to the top of the hull (decking, extra freeboard, cabin, etc.) isn't going to help the stability curve, so it should be kept to a minimum, as much as practical
     
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