comments/help with sailboat without a design

Discussion in 'Sailboats' started by stevedownwind, Jan 1, 2015.

  1. stevedownwind
    Joined: Jan 2015
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    stevedownwind Junior Member

    i'm posting this because i started a project several years ago. i wanted to build a small sailboat with a cabin. i have gone through a number of personality changes during this chapter of my life. i read somewhere that one needs a good chair near a boat building project (somewhere to sit and cry when things are looking bleak). that has proved to be invaluable advice.

    anyway, the boat (if it can actually still be called that, and assuming that i don't burn it in the yard, before i finish), is a 14 foot plywood boat, with a tapered box keel. it is variously built with 1/4, 1/2, and 3/4 ac ext. plywood. i skinned the exterior with 17 ounce biaxial cloth/epoxy resin. doubled on the keel. the deck and doghouse are also skinned with 17 ounce cloth.

    it is primarily a stitch and glue boat with some reinforcements to the interior. it has a number of bulkheads, watertight compartments, etc. measurements in feet and inches are as follows: lod 13.5, lwl 12.5, beam 65", draft 18-20". i'm trying to figure out how much ballast to place in the foot of the keelbox. also i'm trying to decide on a sail rig.

    i invite any general comments, criticisms, etc. as this is my first attempt at building a boat. i have repaired and sailed two larger glass trailer sailors and built 2 stitch and glue outriggers for a canoe and kayak. not too much experience.

    of course the boat is not finished yet. i would love to finish it this year but, based on past performance, other demands on my time, and episodic depression, maybe 2016 would be more realistic. as time and expense goes on, i am increasingly concerned about the design. it looks like a boat but i am quite worried that it won't float right etc.

    it just seemed like an appeal to more knowledgeable folks was long overdue. and i thank any of you for whatever input you might provide. as i look at the preview, i see that my chair is actually in the photo. unplanned but already gave me a laugh. also, i have a number of other photos of various aspects of the building process, if anyone has questions or other comments. steve.
     

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  2. gonzo
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    gonzo Senior Member

    Are the light areas putty or air bubbles?
     
  3. stevedownwind
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    stevedownwind Junior Member

    i think what you are noticing are discolorations in the plywood from earlier applications of epoxy and wood flour. the glass to hull process went surprisingly smoothly, though the 17 ounce cloth sucked up much resin. i had one bubble toward the bow on the starboard side of hull (i think somehow there was a small gob of hard resin on the hull or on the cloth when i applied), still have to grind out and fill that. i will post a picture of the hull on its beam end while i was glassing. it gives a better idea of the box keel and hull shape from the bottom. thanks for the question.
     

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  4. gonzo
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    gonzo Senior Member

    Nice job. Have you figured out the rig yet?
     
  5. stevedownwind
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    stevedownwind Junior Member

    not too sure on rig or sail footage 125 sq ft?. i could definitely use help on that. probably going to attempt a birdsmouth mast or two and bowsprit. i'm somewhat drawn to a yawl rig. i could have more sail variation under different conditions. lower profile. i really don't know how this boat is going to sail though. i may need a taller bermuda rig for any kind of windward performance. still quite a few decisions to make.

    in terms of aesthetics its a more traditional look i guess. my plan was to paint the hull dark green, off-white topsides and cockpit, varnished mahogany toe rail, companionway, hatchcover. maybe some kind of stainless safety rail/line aft.
     
  6. stevedownwind
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    stevedownwind Junior Member

    here is another angle of the roughed in transom, cockpit, coamings, companionway etc. the hatch is formed from plywood and then i have alternating mahogany and cypress slats to strengthen and finish it off. looks fat from the stern but narrow from the bow. and another closeup shot from the bow.
     

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  7. lewisboats
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    lewisboats Obsessed Member

    My observation... that is a BIG box keel, with lots of buoyancy. You are going to need to figure out the cubic footage and determine the buoyancy of it, along with your hull and then determine your light load waterline and then do the math to determine the amount of ballast. I expect it to be quite a bit to overcome the buoyancy of that keel. Trailer weight might be an issue unless you use all or part of the keel for water ballast. All that ballast will probably require you to beef up the structure that supports it. You will also need to consider structure if it capsizes or turtles... you wouldn't want your ballast to head south though the side or cabin.

    Given accurate measurements to the various key points I might be able to model it in FS with would help in determining quite a bit of your Hydrostatic information... at least enough to make some decisions with.
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I don't understand the need for such a contrivance on that boat. That keel is massive and will make a lot of drag, which on a boat with as limited a potential as this appears, just foolish.

    Steve is correct, you have a fair bit of math to do. That boat looks small enough to not need ballast, though with the keel addition, you'll need quite a bit, just to haul her down to a reasonable set of sailing lines. This will just decrease her abilities further and her capacity for crew and gear. Couple this with what also appears heavy construction and well, you might have some freeboard left come launch day.

    A boat of that general size, not counting that keel thing, would be in the 1,000 pound range for displacement at 10" of immersion (hull only). Of course, this would on the heavy side for a 13' 6" boat. A light weight in this size range, would be a few hundred pounds. So, how much does your boat weigh so far?
     
  9. bpw
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    bpw Senior Member

    Or just toss it in the pond and see where it floats and start adding weight as needed, lot easier than doing the math for a boat this size.
     
  10. stevedownwind
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    stevedownwind Junior Member

    sounds like it might be better to cut the keel box back to the hull and start over. with that. any further suggestions? should i put a weighted shoe and centerboard in that case for example? it will be much easier to make that change now than later.
     
  11. sharpii2
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    sharpii2 Senior Member

    The box keel looks to be about 6.0 inches wide with an airfoil shape to it.

    It appears to be about seven feet long, as it appears to be a a little over half the length of the hull.

    It may be eight or nine inches deep at its widest point, but extends up word to fill in the rocker of the hull.

    My guess is the keel itself displaces around 130 lbs.

    I'd use sand or gravel in bags for ballast, as these are easy to place and remove, to get the desired fore and aft floating trim.

    Since the keel starts at the transom, it doesn't extend much past the mid length of the hull, the the Center of Area (CA) of the sail will also have to be further aft than typical, even accounting for 10- 15% lead, over the Center of Lateral Area (CLA) of the keel.

    This might make for an unusual rig, comprising of a low aspect ratio gaff main with a very small jib, or simply a gaff sail alone.

    This would be calculated to get the CA sufficiently aft, while allowing the mast to be stepped in front of the house. A Bermudan main might need a boom extending well past the transom to get its CA far enough aft.

    A boomed lateen sail might also work, but might need a very long yard to get sufficient sail area, which I think would be 90 sf or more. The yard would be considerably longer than the boat.

    How did you build this. Did you have any kind of plan, or did you do it entirely by eye?

    I hope you finish it and get to sail it. It is a very interesting work boat type and should have generous carrying capacity.

    Just a few thoughts.
     
  12. lewisboats
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    lewisboats Obsessed Member

    That keel is more than 2 cubic feet... I would say somewhere around 5 cu ft or about 315 lbs displacement, maybe more.
     
  13. stevedownwind
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    stevedownwind Junior Member

    the box keel is even bigger than what i had anticipated. i originally ran the bulkheads down about 7 inches below the bottom of the hull and framed in the keel box. when i sheathed it i had 2 strips of 12 inch width by 8 ft 3/4 ply. this tapers back to the stern, where the keel is about 7 inches down from the bottom of the hull. i basically left it that way, thinking that i could put ballast in that 3 inch area created by the overhanging plywood, at the base of the keel.

    but steve is correct, it made the keel box much bigger. i have not measured and calculated it exactly, but its about 5 cu ft right now. i could knock that down to 3.5 cubic feet just by removing the overhang that i described above.

    so the various comments are leading me to think that i would be much better off cutting the keel box back to at least the original frame and adding a center plate. this could be fitted so that it swung up into a trunk inside the compartment below the bridgedeck, separate from the cabin (sort of an L shaped foil i guess).

    and yes, i basically did a rough sketch, cut out a main bulkhead, transom, butt jointed a couple of pieces of ply and bent them around. it just got more interesting from there. oh well, its been fun at most points of the project. and i will finish it. but i can't say for sure what exactly it will be when i'm done.

    i really do appreciate the comments and criticisms. they may yet save my project. you guys know way more about boats than i do. i'm just trying to arrive at something that works ok in the end. thanks.
     

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  14. lewisboats
    Joined: Oct 2002
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    lewisboats Obsessed Member

    My personal inclination would be to lop the keel off completely, rig a centerboard or leeboard(s) and if you actually need ballast, bolt it to the sides of the Centerboard case or rig a tray in the bilge to hold the weight securely inside the hull. That keel is going to be more of a brake than anything else. You have a nice wide bottom (please don't take that the wrong way) and a decent amount of freeboard which will do much to keep the boat oriented correctly with the deck facing sky and the bottom facing water and let it stand up to a decent sized sail plan.
     

  15. stevedownwind
    Joined: Jan 2015
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    Location: massachusetts

    stevedownwind Junior Member

    also ability to beach and maneuver in shallow waters. i'm pretty close to sold on a complete keel resection at this point.
     
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