30' plywood sharpie

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

  1. davesg
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    davesg Junior Member

    Looking for comments on 30' sharpie concept

    I've been thinking through this design and am looking for some comments. The idea is a large trailerable coastal boat for three in Florida. LOA is about 30', beam about 7.5', draft board up about a foot. There's about 250 sq ft in the cat schooner rig (is this about right? more? less?) and an outboard well for 6-10 hp. As drawn there is about an 18" lead between the COE and the CLR. The rudder may change to a low-aspect sharpie type underslung rudder but I drew in the dinghy style kickup to see how it looked.

    There is sitting headroom at the dinette area and large companionway hatches. Galley will be a small sink and portable stove, head will be a bucket, there are three large single berths and that's about it. The idea is to have the extreme shallow draft of a sharpie with some stretching out space for three to do a few weeks at a time along to coast or over to the Bahamas.

    Construction will be stitch and glue over a few bulkheads and a mold in the middle. The scale is 1' to the side of a square on the graph paper.

    [​IMG]

    Here's my first try at the lines. I think there is too much flare but I wanted to keep the bottom to 4' wide for plywood. My first thought on scantlings is 3/4" bulkheads, 3/4" bottom, 1/2" sides, and 1/2" deck; any thoughts on that? I'd really like to keep all up weight for tailering under 3500 lbs. I'm figuring on somewhere around 1000-1500 lbs inside ballast.

    [​IMG]

    I'm completely open to suggestions and comments. I wanted to get some feedback before doing the next drawings and starting on the construction details.

    Thanks,
    David
     
  2. troy2000
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    troy2000 Senior Member

    OK, here goes the noob, sticking his head into the hornet's nest.:p

    I'm getting ready to build a plumb-stemmed, transomed plywood sharpie, that will dry sail most of her life on a trailer. When she does go into the water, it'll be mostly on the Colorado River lakes: Lake Mojave, Lake Mead, Lake Powell. She'll be a weekender, not a cruiser or live aboard.

    She'll be about 30' LOA, with a maximum beam of 8' or a little under. I'll be building to workboat standards. That doesn't mean garbage; I'm a third-generation carpenter and woodworker, and I do good work whether I'm building a house or a boat. But she'll be rugged and plain, with simple appointments and painted surfaces, mostly so I can giterdone and get her on the water. I enjoy building and woodworking. But I'm not one of those who gets lost in the process and forgets that the idea is to finish something, so it can be used.

    There's going to be no fiberglass or epoxy anywhere, not even tape on the edges. Not because I don't know how to work with the stuff, but because I hate it. I hate the smell, I hate dealing with the cure times; I hate sanding it, etc.

    She'll be finished in semi-gloss house paint. I have a house built in 1940 that's gotten wet more times over the years than my boat ever will. But it's always had a good paint job, and I wish the inside of the house was in the same shape as the outside....

    I figure most of the beating the boat takes will be on the bottom, from sandbars and deliberate beaching. So I'll double up there, and maybe add some replaceable solid wood skid strips. If the plywood elsewhere checks or splits I'll sand, fill and add more paint. If the checking still shows, I'll live with it.

    I'm sixty years old, and I'm willing to bet the boat will outlast me. If she doesn't, oh well; I'm not out to build an heirloom. My sons and grandkids may have to just bite the bullet, and pony up for a new one....

    I don't have a full set of plans drawn, and may not get around to doing so. I'm a competent draftsman, but I don't have a full-sized drafting table set up any more. But obviously I'll be drawing out some of the details as an aid. I did build a 3/4"=1'"0" model a few years ago to work the shape of the hull and other basics (right before my finances went into the toilet last time), but my younger son promptly ran off with it. There seems to be some things that a man with sons or younger brothers just can't keep. Before I build though, I'll do a detailed model at 1 1/2"=1'0"....and guard it with my life until the full-sized boat is done.

    What I have in mind is generally based on Monroe's Egret (to no one's surprise, I'm sure:D). But she'll be stretched to 30', and widened a tad to almost 8' on deck, without trying to fatten her any more than absolutely necessary at the chines. I'll build her by fastening the sides to a stem, then wrapping them around bulkhead frames at both ends of the cabin, and on back to the stern. Then I'll add chines, gunwales, deck clamps, etc, watertight lockers fore and aft. I may have a stringer or two if I think ishe needs it. She'll have an inside plank keel. And I'm considering rabbeting the chines to cover the plywood edges, since I'm not taping the seams (yes, I have the tools and the skills).

    The cabin will have a bare 4'0" of headroom, which should give sitting room over low settees. I'm considering removable canvas side panels for the cabin, because it gets hot on those lakes in the summer. On the other hand there are mosquitoes too, and there can be some chilly winds in winter.

    Instead of being double-ended, she'll have enough of a transom to flatten the run aft a little when the sides are bent in a fair curve, more like the old racing sharpies. But I'll still carry the stern up out of the water, unlike Brewer's Mystic Sharpie design. If it's on trim with no passengers, the theory is that a crowd in the cockpit should just settle her down enough by the stern to give me a longer waterline. If possible the side planks will be straight top and bottom, tapering evenly back from the bow to the stern. I'll tweak the flare, in an attempt to approximate the old recommendations to have a straight run down from the bow for the first third of loa, a smooth round in the middle third, and a reasonably straight run up from there to the transom. Widest beam will be amidships of LOA, which will put it somewhat back of amidships LWL.

    I'm hoping to squeeze in a minimal v-berth forward (for two people who are close friends, or for one active sleeper), two settee berths, folding table on the centerboard, a very basic galley to port, and a simple enclosure for a portable toilet to starboard. I'm thinking of a sliding hatch big enough to give the cook headroom. If that doesn't work out, I guess we can always BBQ on deck.

    The centerboard will need to be somewhat L-shaped, to give decent access to the V-berth. The rudder will be the traditional balanced inboard type, with its stock flanged so it's easier to remove. The cockpit will be self-draining, which means we may have to choose between sitting on deck or on the cockpit sole, if it works out as shallow as I suspect it will. Ballast will be bricks under the settees and cabin sole.

    For a rig, I'm seriously considering the pirogue or cat-ketch setup; it's a well-proven and simple one. But I've given a lot of thought to a yawl rig, with a short bowsprit that can be run in when not in use. The jib would be boomed; the main would be gaff-rigged; the mizzen would be a boomed spritsail.

    Hopefully, I'd be able to do a panic reef simply by downhauling the mainsail, and run jib and jigger. I had a flat bottomed, double ended centerboard canoe rigged that way for a while, and very rarely even used the mainsail except in light morning airs. Believe you me: I got good at yanking that main down in a hurry. Maybe that just means I was over-canvassed....

    I used to draw some stares when I slid the canoe into the water, and started stepping masts and bending on sails. And an outboard boat followed me with a gal standing up and videotaping me for a long time on Lake Mojave one afternoon, back when camcorders were new.

    Since I'm not as young as I used to be, and definitely not as old as I'm going to be, I figure the mainmast should have a tabernacle. I'd like to be able to swing it down, unfasten it, and slide it forward for trailering.

    There'll be a narrow bridge deck, with enough room for an ice chest under it to port. I'd like to make the ice chest accessible from both the cockpit and the galley, but that might be getting too fancy.

    I've also thought about a well for a very small outboard to starboard, with a mount that would swing it up a little, then tilt the prop back under the cockpit when not in use, with some sort of a flap to stop up the well at the bottom when the motor isn't in use.

    A couple of questions: does anyone have an opinion on whether an outboard somewhat (not radically) off center, and forward like that in the boat with steering being done by the rudder, would work? Does anyone think the boat's too big to trailer and I should go smaller?

    This seems to be an articulate, informed and opinionated bunch on this forum; I'm hoping for some interesting feedback. The target's up and loose, gentlemen....fire at will.:eek:
     
  3. troy2000
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    troy2000 Senior Member

    <moderator note: two similar idea threads merged in hopes of a better conversation togeter>

    I wonder if they have so many people wanting to build 30' sharpies that they should sequester us all off by ourselves in a Sharpies Forum somewhere?:D

    I'm certainly no professional or experienced designer. But my opinion, speaking strictly as another amateur, is that you should give up on trying to keep the bottom at 4 foot. That much flare combined with a shallow draft is probably going to guarantee you'll spend most of your time sailing on your ear. And I'd give up on the split cabin. It looks good, but carrying it straight on through instead will make life below a lot easier. Not to mention easier to build.

    I'm just filling space until the big kids get here though; don't take my word for anything.
     
  4. PAR
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    PAR Yacht Designer/Builder

    Actually the "split cabin" has a lot of merit structurally, though you'll want at least a partial bulkhead there for the mast. Troy and David, there are quite a few of these types of design available currently and the wise thing would be to avail yourself of these plans. No more guessing about load paths or anticipated strain transmission or structural scantlings, just follow the plans.

    I mention this because of you weight goals. When you subtract your desired (or hoped for) ballast from the full up weight of the boat, you'll have to make the whole structure about a ton or so, which seems, well naive to be frank and clearly not something derived at from a careful weight calculation study, which is how a designer does it.

    There are other things I see in your two sketches that make me wonder as well and strongly recommend you acquire a set of plans from a designer. I don't mean to offend you, but there are clear and obvious flaws that suggest a novice designer with limited understanding. We can run through all of these if you like, but honestly it's a lot easier on the ego to just work from a known design, embellishing it as desired (within reason) to create you own special yacht. A number of designers, myself included, have specialized in sharpie designs and can help.

    For example, you may want to consider Glen-L's "Chessie Flyer" or one of Bruce Kirby's Norwark Island Sharpies, maybe one of Jay Benford's or Ted Brewer's designs.
     
  5. troy2000
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    troy2000 Senior Member

    I thank you, Par. Your comments are well-meant, and undoubtedly good advice on top of it. Unfortunately, nothing I've seen is exactly what I want in the way of a lake and river boat for weekends, as opposed to a cruiser or live-aboard.

    For example, Chessie Flyer is a very nice boat. But it's a little beamy for a flat-bottom boat with sharp chines, particularly for a double ender. I don't like the steel centerboard; when I slide over a sandbar with a board down (and sooner or later I will), I want it to kick up instead of rattling my teeth. I don't want a mast in the middle of the cockpit. I haven't seen a body plan or photos from the stern, but if by pinkie stern they mean the gunwales coming to a point beyond a transom, it strikes me as an affectation and unnecessary complication. And so on....:)

    Norfolk Island Sharpie: I don't need or want six feet of headroom in a boat with a 12" draft, and it has a top-heavy, clumsy look to my eyes. The rudder is way too deep for my purposes, as is a centerboard designed to drop down almost to vertical. And again, I don't really like sharing a cockpit with a mast if it can be avoided.

    Brewer's Mystic Sharpie strikes me as entirely too gussied-up for something derived from the simple, clean lines of traditional sharpies. And by dropping the stern to the waterline and adding a fixed skeg, I think he negates several advantages of the sharpie-style boat.

    The Egret as drawn for Woodenboat is too spartan; Bolger's stuff is too boxy to suit me; anything with a keel on it isn't a shoal-draft sharpie; and so on. You get the idea....

    I have a couple of Chapelle's books in the mail, and I'll bury my nose in them when they get here. I've already been through Bolger's books over the years, as well as those of John Leather, John Gardner, Ruel Parker and others. And again I doubt I'll find exactly what I want. So I'll be back to designing my own. And I do have some experience with flat-bottomed boats, although I haven't built anything larger than 16' before. What I have in mind so far falls well within traditional sharpie parameters. I may not win any design contests with it, but I'm not worried about it being a disaster.
     
  6. Brands01
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    Brands01 Senior Member

    I love the idea of building a boat to my own design, and I totally understand others who embark on the same. I'm also someone who learns well from books, and have amassed a substantial library of boat books and think it is possible to do what you're intending.

    You will get a lot of experienced people on this site suggesting you buy stock plans, and they have a very valid point. But it seems you are pretty intent, and are starting out fairly well informed and open minded. Hopefully the big kids won't be too insistent on changing your mind, and will help you change your design into something worthy of the expense and time of building, although I wouldn't be expecting too easy a ride!

    Good luck!
     
  7. frank smith
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    frank smith Senior Member

    Ted Brewer has a nice design all ready to go. There is also a nice one about 30' in one of Chapelles books, I think it is his boat building book.
    Anyway if I was going to design my own I would stat by looking at those for some guidance

    http://www.tedbrewer.com/sail_wood/mystic.htm

    If you stick to the basic recipe ,you should be able to cook one up .
     
  8. frank smith
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    frank smith Senior Member

  9. davesg
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    davesg Junior Member

    I'd like to make very clear that we're following two roughly similar design ideas here. Mine includes the posted drawings that started this thread and is for a stitch and glue lightweight double-ended sharpie with the split cabin, there is also Troy's idea for a sharpie but with a different deck and cabin and built more traditionally. Its hard to keep two discussions in one thread distinct but keep an eye on who is posting what!

    The idea with the split cabin was to get that cross structure in way of the mast and centerboard trunk. This is intended as basically a 25' sharpie stretched out to 30', there just isn't enough room inside to make one big cabin, so there is a berth up forward with its own hatch. I like the layout and I realize it wouldn't be for everyone but that's why we design our own. There is a bulkhead separating the two spaces and acting as reinforcement for the fwd end of the centerboard trunk.

    The Norfolk Island Sharpies and Mystic are all very nice boats but are much bigger and more complicated than I had in mind. The design inspirations I'm working from are Monroe's Egret, Reuel Parker's Egret (http://www.parker-marine.com/28shegretpage.htm), and the sharpies in Chapelle's Boatbuilding (see the 24' Sharpie.) Freeboard fwd should be about three feet, aft less than two.

    Little Bear is a great boat too but still bigger and more complicated than needed. I have a 32' sloop for distance sailing and the 'big' cruises. This sharpie is for gunkholing, sailing the shoals, and trailering.

    Chessie Flyer is another nice design but again, too big and complicated (though still with a displacement of 4000 lbs with 1000 in ballast). I prefer my layout to Chessie's, would like to get the displacement down some, about 6" less freeboard for and aft and of course more length. I like the cat schooner (or cat ketch) rig for its simplicity, two free standing masts with a minimum of rigging. Chessie gets me close but if I'm going to go through the effort of redesigning the rig and the interior then I might as well design the hull as well.

    Given these boats as a starting off point (Parker's sharpie's displacement is listed as 2500 lbs) I don't think 3500 lbs is too unrealistic. Mystic, to my eye a much more complicated but very nice boat is listed at 5500 lbs. I'll figure less ballast than my first guess? Ultimately ballasting will occur after launch to bring things down to her lines and provide adequate stability, the exact weight isn't a major concern right now.


    I'll point out up front that this is an amateur design intended for an amateur build, there are no plans for any kind of production, there are no plans for any kind of sale of the plans. There has not been any kind of weight analysis done, nor careful calculations of anything, this is a first draft and I'd like some feedback before moving onto the next layer of the design spiral (Cyrus Hamlin, Preliminary Design of Boats and Ships.)

    This is completely for my own edification and education. I am an amateur with no formal training as a Naval Architect. I have plenty of reference material available, have read extensively, sailed a bit too, renovated glass boats, done plenty of woodworking, and have a MS in Design and Construction from UF.

    Ultimately I'm designing my own boat not because what I want has never been done before, its because I *want* to have designed what I build, even if the boat doesn't *perform* as well as some of these professional designs. I always appreciate the more experienced patrons first reaction to a newbie being "go buy stock plans" and I think that's completely correct nine times out of ten. If I was buying stock plans I wouldn't be posting here about my own design.

    Par if you'd be so kind as to enumerate your objections to my draft, that's exactly what I'm looking for.
     
  10. frank smith
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    frank smith Senior Member

    It needs a wider bottom for initial stability if you want to keep the rocker and draft minimal . You could do the bottom in 2 layers of 1/2 , no need to keep width at 4' . Too much flair , You said that . I think you have more interior in the boat then there is room for IMO . I like double ended but why lose the stability and room of a transom ?
     
  11. troy2000
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    troy2000 Senior Member

    I agree, Frank; Little Bear is a lot of boat for her size. But at 8'7" beam she's pushing the envelope for a boat to be trailered without a permit. I'll have to wait until I get home and dig out my Atkins books, but if I remember right, she's also heavy for a trailerable.

    And John himself cautions that she isn't fast, as does her dad about Twilight, the boat she's derived from. I'm not a speed demon, but part of the fun of a boat is to see what she'll do sometimes on a breezy summer afternoon.

    Somehow over the years I've missed owning Chapelle's books, even though he's referenced constantly in other author's discussions of traditional-style craft. But I have his Boatbuilding and his American Small Sailing Craft on the way; I ordered them a few days ago.
     
  12. troy2000
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    troy2000 Senior Member

    By the way Dave, I hope you'll forgive me for somewhat hijacking your thread. It does seem reasonable to combine it with mine as the moderator did, since we're both amateur designers talking about a 30' sharpie; it saves some of the members basically making duplicate responses.

    But yes, people should keep in mind there are two separate designs under discussion.
     
  13. frank smith
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    frank smith Senior Member

    Troy thank for pointing that out, I am reading quickly this morning because I really have things that i have to do. But the title is good hook , and I also dig sharpies .
     
  14. davesg
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    davesg Junior Member

    I was certainly thinking less flare and more bottom but the lure of a single width of ply was too much so I thought I'd see what the group though, I'll add some width and lay it up with a couple of layers. The rocker is there because that's what everyone says about Egret and similar sharpies, keep the stem out by a few inches at rest, and the stern too for reserve buoyancy.

    I know the debate between double enders and transoms. I really love the aircraft carrier look for the 'Open**' boats, and Graham Byrnes's EC22 would be high on my list if I were to build front stock plans. I don't intend this to be a planning boat, even in ideal conditions, so I didn't see much great advantage in dragging around all that transom. If I were to go transom I think the thing to do would be to cut things off a few feet shorter and have a wide open cockpit without transom for easier boarding/swimming. That sort of compromises the traditional look and I think would unbalance the appearance with that big aft house too close to the stern. A transom would make this a very different boat and even at this early stage of concept there are some things that have to be decided, double-ended is one of them.

    I can see maybe too much interior too, first draft and all that. The big thing I see is the cabinets in the saloon are too far outboard, they need to come in, the low freeboard there, about 30") means they need to be completely inside the sidedecks to have any counter at all. I may have a counter on one side and just shelves on the other. What else should I be looking at in the interior. I did some measurements on the berths/fold out table and they looked okay but I may have missed something.

    My construction concept is to scarf up full size topsides (hence using DelftShip, it will expand the developed panels for me), bending those around bulkheads and a mold or two and then adding the bottom. The 30' long sides will be a bear to handle but I can find some extra bodies for an afternoon to get them in place.

    Troy, no problem, lots of room in here for two discussions, I just want to make sure we don't all start talking past each other. The big difference I see between our projects is the construction method, you're looking for a more traditional project and I'm a resin and glass devotee. You'll really like Chapelle's books, it seems wild you've never come across them. In fact he's got almost exactly what you're looking for in Boatbuilding, there's a 24' Sharpie that is really quite perfect. I don't think you'll get the interior you're looking for, but maybe if you stretched things out to 30' it could hold a little more. Really any sharpie (Monroe/Chapelle type anyway) is just going to have some room to crawl in out of the weather.
     

  15. troy2000
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    troy2000 Senior Member

    Dave, the last time I was considering Chapelle's books, the only local bookstore that carried them wanted stunning amounts of money for them. Or at least the prices looked stunning to me, compared to the balance in my checkbook at the time. Of course, that was pre-internet days, and it never occurred to me to ask other bookstores about ordering them.

    This time around, I just looked for the cheapest price online from someone with a good rep, and saved almost forty percent off list price. It was almost too easy. If I don't watch it, I'll be building another bookcase.
     
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