bulb keel on a "traditional" sharpie

Discussion in 'Sailboats' started by peterchech, Aug 18, 2011.

  1. peterchech
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    peterchech Senior Member

    This is all theoretical, but...

    Has anyone put a lifting bulb keel on a "traditional" sharpie?

    I really love the looks and supposed performance of the 27' new haven sharpie (offsets/scantlings are in reuel parker's shapie book). If someone put in a self draining cockpit, extended the cabin aft just a few feet, and threw in a lifting lead bulb keel, wouldn't this make the boat much more seaworthy? Would it totally alter its performance, negatively or positively?

    I mean, an i-550 is pretty much a sharpie with flared topsides and a bulb keel, no?
     
  2. philSweet
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    philSweet Senior Member

    The sharpie was optimised to do a particular job safely and cheaply. The flat bottomed hull can perform decently over a wide range of payloads and with a fairly high CG. A yacht conversion doesn't need the payload range of the workboat, and adding a drop keel and accommodations tosses the cheap out the window and lowers the CG. All of which points to a different hull form being more appropriate. At 27' you can still balance a moderately powered sharpie by moving the crew and a couple sandbags. If you are determined to open the boat up a bit, twin bilge boards can be used with room for an air mattress between. I'd recommend a file bottom hull. This is an improvement when the cargo load doesn't need to be 8 times bare hull weight. It also gives you a place to put the bilge pump, and the water will collect there, at least while you are at anchor; and the water will drain out the transom plug when on a trailer. A selfbailing cockpit would be about 3" deep on this boat. Take an oak 4x4 and resaw to 3/8" thick for floorboards laid on small floor frames spaced about 12" if you want dry feet. The three boards outboard each side fixed to the frames and the middle few built on a removable grate held in with a pin. Sharpies need either some agile, movable ballast or they need to be loaded down so that the waterline miship is about 30-35% up the side of the hull. (I'm going by traditional freeboard, mathematically, the ideal draft is mostly a function of beam.) They are not particularly fast if ballasted for single handing, but they are wonderfully rewarding to sail.
     
  3. peterchech
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    peterchech Senior Member

    Why do you consider them rewarding to sail?
     
  4. CutOnce

    CutOnce Previous Member

    Seaworthiness is a topic that is hard to pin down to a single set of fixed criteria. What works in one venue may be totally inappropriate for another. And what you consider seaworthy is an issue as well.

    There is a world of difference between a seaworthy daysailor and an offshore boat designed for overnights in open water (or there should be!). There is a huge difference between seaworthy cruising boats and racing boats.

    Much of seaworthiness resides in the judgment of the person making decisions - when to leave anchorage (and more importantly when to stay), what sea states are acceptable, what the long range forecast looks like, what bail-out options (running for shelter) are available, what kind of auxiliary power is present etc.

    From your posts, I'm getting the feeling you are trying to evaluate how to achieve maximum boat at minimal cost/build effort. The relatively simple hull form of the sharpie is a bargain at the i550 level for a whole bunch of reasons - the scale of the expensive parts is small enough that it is within the dinghy world, and not priced in the cruising/racing world. Once you cross the threshold out of the dinghy world & three stitch & tape scarfed plywood panels, boat costs become more a function of per pound or per foot pricing and the hull form becomes much less of a cost factor. You also quickly leave the one-man garage build world behind and get into thinking in terms of a year+ build instead of weeks/months as a homebuilder - which also brings divorce/family pressures into the picture.

    Building is expensive right now, and buying used is cheap. If you are comparing a used boat as a project versus a new one, the used boat will win out, even if you have to do some work to get it right. Better to take advantage of someone else's economic misery, than to bring it on yourself.

    In answer to your direct questions above, yes, I think a sharpie hull can be externally ballasted and provide good performance and seaworthy safety. The i550 has proven that it is comparable to other similar sportboats in all aspects. It gives up some upwind speed against some, and gives up some comfort, requiring a bit of heel going upwind to avoid pounding. It would not be a fun boat to be below in using the head on a long crossing, especially going upwind. A slightly larger sharpie of similar design would certainly be more accommodating in almost every aspect. The 7 meter sportboat world presents a serious cash leap above an i550 - almost double the cost to build a Shaw or similar for 7 feet more LWL. And the stuff to equip that extra 7 feet is a major part - not the raw hull cost.

    The i550 is targeted at the sportboat niche - basically day sailed racing with little to no offshore intent. Cruising, even performance cruising is a great sharpie fit - but best if you give up the drop keel with bulb and go to a beachable dagger-style lifting or swing keel. With a sharpie hull you are giving up a lot or beaching and shallow water fun when you add the bulb. I'd take a hard look at the Gougeon's i550 mods - the lifting ballasted board makes more sense than a bulb for most use.


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    CutOnce
     
  5. DCockey
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    DCockey Senior Member

    The Star has a sharpie-like hull, though with a shallow arch bottom and a bulb on a keel.
     
  6. PAR
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    PAR Yacht Designer/Builder

    The i550 isn't remotely related to a sharpie, except for it's flat bottom. The Star has a B/L ratio of less then 4 and though a very small percentage of sharpies have had arc bottoms, there are enough glaring differences to not call it a sharpie.

    You could put a bulbed fin on a New Haven, but it wouldn't really help much, in fact it would probably slow it down, with the extra drag from the bulb. The other changes would likely ruin the boat. Raising the cockpit so it's self draining would probably "tip" the stability scale quite adversely. This is common of sharpies, you better keep them low or you'll pay dearly.

    As has been pointed out, "seaworthy" is a speculative term and everyone has their own idea what this might include, especially among designers. If you want a seaworthy sharpie, then select a bigger one then the 27.
     
  7. peterchech
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    peterchech Senior Member

    To be honest cutonce, you hit the nail on the head. I have been checking out some used glass boats, and for about 3K I can pick up a hunter 25 in relatively good shape. Maybe not my "ideal" boat, but still a capable and comfortable cruiser that my girlfriend will like. And I could never build anything remotely as big for 3K...

    I think you're right that once you move beyond the "dinghy world" costs explode, and build times do too. Truth is, I love building small boats. It gives me something stimulating to do when there's snow outside. But I don't know if I have the stamina for a build that lasts more than a year. So most likely I will go with the Hunter, and build something small and sporty like the i550 in my spare time during the winter.

    But the evolution of Sharpies fascinates me, and that is why I started this thread. Thanks PAR for your informative post. Lack of a self draining cockpit makes storage a PITA because every time you tie up you have to fit a tarp/cover. You really think on a 27 foot boat you have to sit on the floorboards? No wonder there are few Sharpies sailing today...

    I can see why the bulbed keel might slow down a sharpie with some extra drag, but how could it NOT make the boat stiffer and more powerful? And what if the "bulb" was instead made into a foil shape a la gougeon hot canary and installed on the end of the CB?
     
  8. PAR
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    PAR Yacht Designer/Builder

    All bulbs create drag, some more so then others Peter. In some designs, the drag associated with the bulb is over come by the RM improvements, which permit more area to remain aloft longer. These types of boats generally aren't remotely shaped like a sharpie and are designed to take advantage, of the extra area this higher ballast ratio permits.

    You seem to be misunderstanding what stiffness does. Yep, you can add a bulb, but if the hull form can't take any more area then you're just "burdening" her with something she can't use. Yes, a bulb could stiffener her up, but what's the point if the hull form isn't going to be able to take advantage of the extra stiffness and area?

    A larger sharpie would have a sole grating and pumps to keep your feet dry. If preformance isn't your primary concern, then several cruising sharpies in the 30' - 34' range do have self draining cockpits. Ted Brewers, 32' Mystic sharpie has a self draining cockpit, but don't ever think you're going over a 1.35 S/L ratio (8.25 MPH) in this beast. You can get her to surf, but only in near gale force wind strengths, regardless of if she has a bulb and fin, unless the bulb had a jet drive in it.
     
  9. CutOnce

    CutOnce Previous Member

    All:

    I think the discussion has taken a direction that I encounter every day in my work world. I work with communications technology, and that arena has it's own language, terminology and science. It is fundamentally impossible for a layman to be able to understand and participate in a conversation that effectively discusses issues, because they lack the knowledge of the basic building blocks of the language. This isn't to say the layman is unintelligent, or doesn't understand much of the discussion - but they often misinterpret things because the meanings of common words are different in my work world. It takes many years of focused education and experience to create these communication problems!

    To some degree, I think peterchech and I as interested amateurs are making terminology errors which are serious mistakes to PAR as a professional. What we have lumped into our view as a "sharpie" is completely wrong to PAR. Because our characterization of the i550 as a sharpie is wrong, as a professional he is then trying to fit his very clear understanding of a historic sharpie - and he's certain it doesn't fit with our needs.

    The other problem I think may exist is that my background as a dinghy sailor (and to be honest, my lack of forty years experience with displacement hull sailing) is confusing as well. I sail high performance dinghies - very light planing boats with trapeze, spinnaker and zero stability. To me, the i550 is just a bigger dinghy with the added benefit of "training wheels" in the form of a lightish bulbed keel. The bulbed keel isn't providing anything like a real displacement hull's ballast - in my view it makes the i550 (which is fundamentally a dinghy in my view) tamer and safer than most other dinghies. The boat is still designed to plane, will still fall over if you aren't careful - but is one hell of a lot easier to go out with my wife than anything I sail (boats that prefer to be upside down).

    So what I'm saying is that PAR is right - and so am I. But we aren't speaking the same language, and his interpretation (technically correct I'm sure) differs from mine.

    I think I understand my work client's frustration in trying to communicate with me a little better. I've learned it is easier to avoid in depth discussions and arguing terminology in favor of really trying to figure out their actual needs. I guess it works out reasonably well, because everyone seems happy even though we don't actually speak the same precise language.

    --
    CutOnce
     
  10. PAR
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    PAR Yacht Designer/Builder

    CutOnce has a good point and I should have been clearer. A take a sharpie as being a 6:1 beam/length ratio and several other factors. In smaller sizes 5:1 B/L is common, though in all honesty, there's no such thing as a small sharpie, because of the high B/L ratio. The sharpie has gone through an evolution in the last hundred years, dividing into three basic categories, the traditional (read heavily built), the modernized (read taped seam) and the skiff.

    The 32' Mystic, by Brewer is a classic if quite fat, modified sharpie, but it has enough styling cues to make it acceptable as such. The Chapelle drawings in several of his books are much better examples of this type. In the 1950's with the advent of plywood's acceptance in boat building and much better adhesives, new, much lighter though very similarly shaped sharpies where being built. The resulting structures started and eventually eliminated much of the internal framing, making them considerably lighter. Lastly comes the skiff, which is a truncated, fattened sharpie to a large degree.

    The skiff form has seen the most evolution as folks realized it could tolerate a bigger press and it's square butt could provide enough area to plane off. This has been carried to great exasperation in recent decades, making the skiff a set of (several) categories all to it's own.

    The i550 is a full plane mode dinghy. It's triangular waterlines show precisely what it's designed to do, quite unlike the sharpie. The bulb on the i550 is unnecessary in my opinion, though I suppose you could eliminate a crew member with it in place. The boat would probably be faster as just a centerboarder or daggerboarder and a crew fully engaged at keeping her upright.

    Peter, a fin mounted bulb could make the sharpie stiffer, but she can only do so much with her waterlines and typical sharpies don't have enough bearing area aft, to take advantage of the extra stiffness. On the other hand, if you fatten up the butt of a sharpie and installed the fin/bulb, maybe you'd have something (a skiff), but now you're into reinventing something that already exists.
     
  11. peterchech
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    peterchech Senior Member

    That is very helpful PAR as always, thanks.

    Cutonce, funny how women influence what we do so much, huh?
     
  12. gonzo
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    gonzo Senior Member

  13. Tad
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    Tad Boat Designer


  14. sharpii2
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    sharpii2 Senior Member

    Somebody did put a ballasted drop keel in a modernized version of an 'Egret' sharpie. An 'Egret' type has flare to its sides and has a pointed stern. This boat was in an issue of 'WoodenBoat' a year or so ago.

    The drop keel resembled a dagger board and had a slab of lead inside it, rather than a bulb. Such would almost certainly improve the range of stability on such a craft, as long as it could be locked down.

    The thing is not to over do it, or you will end up with a boat that sails too upright. With most sailboats, this is desirable. Not so with a flat bottomed sharpie.

    If the sharpie sails on its side somewhat, its sharp chine forms a "V" to the sea which provides a softer ride.
     
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