30' plywood sharpie

Discussion in 'Boat Design' started by davesg, Nov 4, 2009.

  1. luckystrike
    Joined: Feb 2010
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    Location: Germany

    luckystrike Power Kraut

  2. luckystrike
    Joined: Feb 2010
    Posts: 251
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    Location: Germany

    luckystrike Power Kraut

    Introducing my 26' Coastal Sharpie

    After talking with Troy, the most aktive member on this thread, I would like to introduce me and my design for a 26' Coastal Sharpie...

    Person:

    My name is Michel and I live in Wilhelmshaven, north-west of Germany. I'am 44 years old and I'am working as an instructor for social disadvataged kids (no, I'am no know-it-all teacher). Beside this I'am running a part time business for boatbuilding, speciallised a little in building foils and other parts for dinghies and beachcats. Repairing and building small boats and tenders.

    Sailing is my passion since I was 9 years old, my home water is the North Sea Coast and it's Wattenmeer. I like cruising as well as racing. My own boat is a "classic" Tornado Cat, which is my afterwork boat. For racing I'am part of the crew aboard the 40m²Jollenkreuzer "Schrexe" as helmsman and co-skipper. (See www.schrexe.de to take a look) This boat is on sale now and in the future we mostly will sail aboard "eeeasy", a Dehler 34 (old version) which will enable us to sail major offshore races such as "Kiel Week" or "Nordseewoche".

    Designing:

    My interest for designing sailboats is pure hobby and I have (until now) no real ambition to make a buisiness out of it. But the design process is what I like, solving problems and try to bring out a boat that looks and sails well.
    It all started when I looked at design drawings and felt that this or that detail should be modified to fit my taste or needs. I think everybody has this thoughts but thinking / feeling is one thing, but doing it is another. So one day I was sitting on my drawing desk and began to design a boat.
    Until now I have drawn 4 designs and two (and a half, my own) of them have been built (succesfully). I always work with paper, fairing battens and calculator.


    Design Philosophy:

    My design philosophy is the Kiss principle (keep it stupid simple) and I always try to find the most simple and cost-effective solution, but that has to be useful and pleasent to the eye. As I'am a experienced sailor and a successful racer in particular (local hero only ), I always have an eye on a good performance, even in cruising designs.

    My paragon is Dick Newick

    Start Point for the Egret Evolution:

    When I saw the seagoing Egret of Reuel Parker inside the Sharpie Book my thinking started to devellop the Egret to a boat that would be a more useful design and would be able to sail in our waters. The North Sea has large flat water tidal areas (Wattenmeer) as well as difficult offshore conditions (again with strong currents).

    The qualities of the boat:
    The very simple, fast and cheap construction with flat bottom, straight flared sides, and relative light displacement
    The traditional look with her freestanding wooden masts and just two working sails
    The shoal draft and the good sea going abilities.



    My design goals are:

    - better hydrodynamics for a better overall performance, better self righting ability with secured calculations
    - more comfortable and practical interior with 4 bunks and sitting headroom over them, a lower centerboard case, cooking- and navstation.
    length down to 26' for easier and cheaper construction, lighter wheight and better trailer ability
    possibility to integrate second-hand eqiupment into the boat (for example a finn-dinghy or Ok-dinghy rig as mizzen mast), different sail rigs possible.
    careful nesting of plywood parts for material efficiency, resulting in cheaper construction.
    screw and glue contruction, possibility to avoid epoxy (allergic persons)
    minimum running rigging with
    auxillary power by electric motor (torqueedo or similar) for a greener world
    towed on the trailer by a normal sized, fuel efficient car (100hp VW Passat, Audi A4 or similar).

    These are my goals. We will see if this is all possible in one boat and still looking acceptable.




    26' Coastal Sharpie, Design no. 5, Working Title: "No Regret!"

    Technical Data (so far):

    LoA 7,90 m Sailarea total 28 m²
    LWL 7,00 m Main 19 m²
    LWL effective 7,55 m Mizzen 9 m²
    BoA 2,32 m
    BWL 1,64 m
    Draft 0,55 / 0,95 m
    Displ. on CWL 1370 kg
    Displ. light 1100 kg
    Displ. empty 900 kg

    Details

    Three major details in this design will let sharpie purists burst into tears and they will say: "this is no sharpie or an Egret anymore". But these details have some serious advatages.

    The shallow keel, in which the centerboard is housed. It's quite easy: There are two drawbacks and 6 advatages over the traditional arrangement with the big centerboard case inside the boat:

    Drawbacks:
    1.The minimum draft increases to 55cm or 1' 10'' (at this stage of design). This can cause some trouble in very shallow areas and it makes beaching more uncomfortable
    2.This keel is not consistent with the traditionalists mind.

    Advatages:
    1.Capsize stability posssible with less ballast due to the greater leverarm of the keel.
    2.A lighter boat for better performance and better trailer-ability (smaller car needed)
    3.Better sailing stability overall and when sailing with minimum draft
    4.Much more uncluttered and comfortable cabin space
    5.Grounding will penetrate the keel, not the bottom of the boat. To come free you can heel the boat to reduce draft.
    6.Centerboard pivot pin is outside the boat, no water inside from a seeping pin.

    The keel will be made from standart steel U-profiles shaped into a streamlined form and covered with plate material. Leadballast will be poured in afterwards in small steps. Or leadballs are given into it and secured by concrete. The centerboard is made from steel also and is hoisted by a pulley. All in all, two or three days of ugly work with a big flex and the help of a professional welder.

    When I do the stability analysis I will know how much ballast there has to be and if the draft can be reduced by lifting the case a little bit inside the boat. A rough estimate calls for 350 kg (~770 pound) of ballast.


    The Stern is not the charismatic ducktail of the original "Egret" anymore. In my tries to draw the chine into the water flow to increase sailing performance, it became obvious that my sharpie will become a relative wide transom. The rocker line ist flattend for better surfing and sailing beyond hullspeed.

    The Mizzen of the cat-ketch-rig stands in the middle of the cockpit, holded by a bridgedeck on seat level. This forms a seperate room for the helmsman and a "social cockpit" for 4 to 6 people. (1,4 m long by 1,9 m wide). All sheets are based on the bridgedeck to be easy accessable by the helmsman or the crew. It's possible to fit a standart ok-dinghy rig in a guiding tube.

    Thats it folks. I'am open for comments. But please notice that the drawings are not completed. So pressure and flotation points, keel and rig positions are not correct. The mizzen is to big in the current sail plan.

    By the way; on saturday I'am off to go sailing at the Kiel Week and on holyday afterwards. Don't wonder if I don't responde on your comments in the next three weeks.

    Grrreetings from the North Sea Coast, Michel


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  3. wayne nicol
    Joined: Dec 2009
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    wayne nicol Senior Member

    cool so far

    that looks great so far,
    sorry to see the "double ender" get lost.
    but i understand your thinking with regards to performance.
     
  4. troy2000
    Joined: Nov 2009
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    troy2000 Senior Member

    Thanks for posting your design, Michel. Or what you have of it so far, anyway.

    You're right; between the keel and the beam/length ratio, I wouldn't call it a sharpie. But that's OK. It's an interesting boat anyway, and a close cousin to sharpies. I hope you keep posting as you work out the details.

    I reworked the cabin top on my model, to give it more crown. Between the tumblehome of the sides and the fact that they follow the beam of the deck, it has a nice sheer now, and is a lot less boxy. Of course that cuts into the headroom more, so I'll probably wind up making it a poptop somehow.

    Unfortunately I'm here, and the camera with the pictures is 168 miles away. So I won't be able to post them until next week when I go back to work. Right now, I'm taking a little vacation time.

    I'm not wild about the keel, of course. Among other things, if I'm going to ground out I'd rather do it on a flat bottom than put leverage on a keel. But I'm sure it'll improve performance. I've thought of putting a steel or iron shoe down the centerline of my bottom, then trimming the boat with internal ballast as needed.
     
  5. luckystrike
    Joined: Feb 2010
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    Location: Germany

    luckystrike Power Kraut

    No Regret

    Wayne and Troy,

    yes you are right, it's a pity (a little bit). But my aim is not to design another replika of the wonderfull "Egret", which would be no. 4 (Wooden Boat, Parker, Chapelle`s Lady B ). I want to take this wonderful concept of the coastal sharpie and bring it into the 21 century. A very useful boat to sail good and safe, being comfortable in the habour.

    The basic ratios and propotions of the Parker Egret (bottom- and waterline length/beam as flare of the bulkheads are nearly the same. The greater overall beam is caused by the raised deck level.

    First calculations and my nesting plan show that the construction will be very cheap. The hull, deck, cockpit, cabin and bulkheads will use 3 sheets of birch multiply (5x10') of 15/18mm, Marine plywood: 12 (4x8') sheets 10/12mm (1/2''), 8 sheets 8/10mm (3/8'). Add 2 to 4 sheets of 1/4' for the basic interior and compare this with the material list of the NIS 26!

    My wish is to design the folkboat of the 21 century ... fast, easy and cheap to build, able to sail everywhere.

    Michel
     
  6. luckystrike
    Joined: Feb 2010
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    luckystrike Power Kraut

    You're right; between the keel and the beam/length ratio, I wouldn't call it a sharpie. But that's OK. It's an interesting boat anyway, and a close cousin to sharpies. I hope you keep posting as you work out the details.

    Of course I will keep on posting. I will continue drawing in roundabout three weeks time, when my vacation is over.

    I reworked the cabin top on my model, to give it more crown. Between the tumblehome of the sides and the fact that they follow the beam of the deck, it has a nice sheer now, and is a lot less boxy. Of course that cuts into the headroom more, so I'll probably wind up making it a poptop somehow.

    I'am curios how it will look with this modification.

    I'm not wild about the keel, of course. Among other things, if I'm going to ground out I'd rather do it on a flat bottom than put leverage on a keel. But I'm sure it'll improve performance. I've thought of putting a steel or iron shoe down the centerline of my bottom, then trimming the boat with internal ballast as needed.

    Sorry, my english is good enough to fully understand what you mean. Are you talking about my keel or yours? Can you please say it again in easier words?

    Michel
     
  7. troy2000
    Joined: Nov 2009
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    troy2000 Senior Member

    I meant to say I don't want a keel on my boat like the one you're designing for yours. I think there is less chance of damaging a flat bottom with no keel than damaging a boat that has a flat bottom and a keel.

    If you push sideways on a keel, it puts a lot of force on the connection between the keel and the the hull. Of course, your keel isn't going to be very deep, so maybe that isn't a serious problem.
     
  8. luckystrike
    Joined: Feb 2010
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    luckystrike Power Kraut

    Ballast Details

    Troy,
    aaah, now i understand. Yes the connection between keel and bottom is no problem and the keel is only 1' 2'' deep. The bottom will be very strong (18 mm) and of course there will be some stiffeners across it (sorry, don't know the correct term) to take the loads from the keel and there is a longitudial keelson.

    Same is for the centerboard. From my practical experience with "Jollenkreuzer" sailing it is no problem to raise the daggerboard even with side pressure from running aground. Many people have the fear that the steel centerboard will bend outside the case when grounding, but this is a pure theoretical fear, in practise this is no problem.

    As your sharpie is intended to sail on inland waters you will not need positive stability for 120° heeling. 65° to 80° should be more than enough to sail safe in strong winds. But a steel shoe outside the hull is a good idea anyway. Even if your ballast is only 6'' deeper than inside, you will save a lot of them and you can move your pivot pin of the centerboard to the outside of your hull...eliminating one more possible leak and having a lower case for more comfort inside.

    Michel
     
  9. troy2000
    Joined: Nov 2009
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    troy2000 Senior Member

    I found my camera this morning; it was in one of my toolboxes. So here are some views of my model with rounded corner posts on the cabin, and a temporary cabin top taped on.

    They're very poor pictures. I took them against a dark background, and the contrast washed out the details of the boat. There's also a strange kink at the back of the cabin, where I didn't fair the mizzenmast notch down properly before taping the top on. But you can see the general shape.

    I could probably go into Photoshop or Picasa and tweak the pictures--or better yet, take some more. But I don't want to take the time, because my son and I are starting on a 16-foot flat bottom canoe this morning. Yes...we're taking pictures, and I'll post a thread on it.

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  10. luckystrike
    Joined: Feb 2010
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    luckystrike Power Kraut

    Looks good!

    Troy,

    this looks far better. I hope you have left enough headroom for comfortable sitting. Sorry for beeing inconvinient and to say it again, but I think a marked waterline on your model would help you to devellop your details.

    I wish you much fun with your son and the canoe!

    Michel
     
  11. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

    It's looking good.
     
  12. luckystrike
    Joined: Feb 2010
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    luckystrike Power Kraut

    At last ... steps forward

    A friendly Hello to everybody!

    The Summer is nearing it's end and there is some time to go back to the drawing desk and do something different than sailing, working and beaching.

    Design Spiral No. 4 is finished now and I will build it as a model in 1:10 scale. Hopefully right in time to do some rc-sailing when the real boats will be out of the water for winter.

    Centers of flotation, wheight, lateral resistence and sail area are balanced to each other and a stability calcuation (90°) shows that it will need 290 kg of ballast in the keel for having 40kg upwards at the mast top. Praise the flared bulkheads!

    Developments of DS 4 are: Bottom width increased to 1,48m, resulting in a BWL of 1,68m and a ratio (CWL/BWL) of 4,5.

    Freeboard increased overall by 2,5cm (1'') to be 67cm (~2'2'') at the lowest Point midships.

    Goodbye balanced spade rudder and welcome transom hung rudder. Mostly for simplify building, but also to increase its efficiency. I have to look for a solution to give it a more traditional look.

    The attachments show the construction-bulkheads (bh) built to deck level fixed on there individual positions. Bow piece is still missing.

    The model will be built the same way as the original (perhaps some time in the future). Unlike the original which will have three diagonal running bh's (raked transom, main- and foremast-bh to increase internal room), the models bh's are all vertical

    I will sail one last (or last but one) race for this season on saturday / sunday and should be able to fix the bow section as well as sheer and chine stringers until middle of next week. Then you can see the lines and the shape of the boat in 3D.

    So long, Grrreetings from the North Sea Coast, Michel
     

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  13. troy2000
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    troy2000 Senior Member

    It's a pleasure to see what you're doing there, Michel. I look forward to more pictures as you build and sail the model--and pictures of the full-sized boat too, when you get around to building it.

    I've had my model on hold for a while. Partly because I think I answered to my own satisfaction some of the questions I was trying to answer with it; partly because I sidetracked into building a real (but much smaller and simpler) boat with my son, and partly because I was waiting for the design catalog I ordered from the Smithsonian. I wanted to order a couple of Chapelle's plans from it, to compare with what I have in mind.

    The catalog I ordered never showed up. I was patient for a long time, because I had heard they're slow sometimes. When I finally sent a follow-up letter, they told me they had never received my check. I finally figured out why this weekend: while cleaning out my pickup, I found the letter with the check under my seat. Apparently it slipped out of the stack of letters I was mailing, and disappeared out of sight.

    Ah well...I sent another check this morning, and made sure this one got into the mailbox.
     
  14. Boston

    Boston Previous Member

    I thought your son was off in the war
    if not then glad he is back
    if so then you have my best wishes for his safe return

    on a whole other note if you have been following my thread on my latest pick of the passage you will notice its got a sharpie hull with a box keel under it

    fast and efficient is the word I get

    cheers
    B
     

  15. luckystrike
    Joined: Feb 2010
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    luckystrike Power Kraut

    It's a pleasure to see what you're doing there,
    Thank you!

    I answered to my own satisfaction some of the questions I was trying to answer with it; partly because I sidetracked into building a real boat with my son,
    A wonderfull project, I hope you both have tons of joy with the canoe! Sometimes it has its advantages to do something different ... it opens up the mind for new ideas.

    ...partly because I was waiting for the design catalog I ordered from the Smithsonian. I wanted to order a couple of Chapelle's plans from it, to compare with what I have in mind.
    Normally I do this the same way and it's a good starting point! I just bought "American Small Sailing Craft", but it didn't took me forward. After learning (to my deep disapointment) that the "Egret" replica from Wooden Boat seems to be a very poor sailer in more than 3 Bft, I abandoned to look for further historic paragons and better follow my ideas of "good lines" for a sailing boat.
    It may be, that I'am at a piont where I "boldly go where no one has gone before" :D Now it's hard not to stick to the concept of the NIS Boats. :confused:

    while cleaning out my pickup, I found the letter with the check under my seat.
    Funny thing! The same happens to me with my pencil, my calculator, my mobile phone, my "I need it now and have no hand free".

    :idea: I have a little bucket where I throw in everything small and important

    Grrreetings from the North Sea Coast, Michel
     
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