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NOTE: Version 4.0 May 12, 2011 -- Added step 7 about a brief trimaran conversion for the Everglades Challenge. I talk more about sailing (and other things) at my blog, Tristram Shandy in the 21st Century, www.tristramshandy21st.blogspot.com --wt
Foreword According to the philosophy of "one boat for each day of the week," I built my Tuesday boat. The Monday boat was described in my instructable, Make Life Better with a Sailboat in a Closet. This Tuesday boat reflects some lessons learned from the Monday boat, some changed situations (for context always has a finger in the things we build), as well as the usual misguided notions that exist to help us set benchmarks for all human values.
What it is This boat is a tacking outrigger sailing canoe. It is a 3-board canoe, which means, in Western boat-building tradition, the main hull (vaka, in Pacific boat-building tradition) is a sharpie-style hull. However, the outrigger float (ama), is a two-board hull (Wharram style; more on that later). The sailing rig is a Western cat-ketch made from standing lugsails.
Youtube: See it in action here: http://www.youtube.com/watch?v=1L4J5EKSwEc This is the better of the videos so far, though a few more are posted under 'wadetarzia'
Specifications:
Materials: 1/4 inch CDX plywood, common pine for stringers, laminated pine shelving/desktop materials for boards, oak and Douglas fir for load-bearing struts, Douglas fir flooring planks laminated for akas/cross-beams, 6 oz. glass cloth, System Three epoxy, a few bronze ringnails, some stainless steel hardware, a few commercial blocks and cam-cleats, and low-stretch synthetic line for halyards, sheets, and downhauls.
Vaka/main hull: sharpie style, chine and epoxy construction, 16 feet length-overall, ~4 incnes rocker, 8 inch waterline at center with one person aboard, 24 inches main hull beam including gunwales, 14 inches beam at bottom, 23 inches depth of hull at center, ~19 inches depth at ends. Main hull weight about 160 pounds (glass and epoxy over plywood, double layer on outside bottom, single layer on inside bottom up to waterline. Open hull with partial decks and foam flotation.
Ama/outrigger float-hull: 14 feet length overall, 14 inches beam at center, 14 inches depth at center, strong rocker, V-hull style. Decked and watertight with screw-hatch access/ventilation. Weight about 70 pounds. Displacement: about 270 pounds.
Akas/crossbeams: Laminated from 4 strips of DF tongue-and-groove flooring planks (tongues & grooves adzed down), tapering to three strips toward ama-end, ~7 feet long (should be 8 feet but that's what I can scrape through my garage door). Weight about 15 pounds each.
Assembly: The parts are lashed together with 3/8 poly line (1/4 would be OK but use good quality marine low-stretch line) and tied off on plastic cleats. I use half-inch oak locating pins to lock the relationships of the aka to the main hull, but the whole lashed boat is still quite flexible, which is good for an outrigger canoe. Total beam is 7 feet.
Not so Right, Not so Misguided So you are wondering how this canoe represents a misguided notion? I started building it from cheap materials (CDX plywood and Home Despot lumber) because I intended it to be practice for the larger outrigger I wanted to build and build properly. Instead, each hour on the job, I invested more time, and more thought, and by the time I was done, I had so much time and money invested that it had transformed into THE BOAT. His name is Short Dragon.
Lessons are to be learned here, so do what you can. Meanwhile, I will tell you how I made the boat.
And More! Well, not yet. A few more things: Short Dragon has really pleased me. He is a good performer. If you are smarter than I am, you can build a better one easily by using better materials and having better skills. You can build it lighter by using fewer stringers, less epoxy and glass, etc. This boat weighs in fully rigged at around 280 pounds. But no matter. My economy car tows it just fine, in 5-10 knots of wind (reported from local airport weather probes, not known at sea-surface) he will cruise along at 5 to 7 knots. I have often hit 10 knots, sometimes 12 knots, and in one blaze of glory hit 14 knots, although we were probably "pushing the envelope" (blah, blah) near disaster.
Sailing not Paddling (Mostly) He would not be the best paddling craft, of course, with his boxy hull and heavy outrigger, but often I have had to paddle home after the dusk wind dropped me a mile or two from the ramp. In flat water you can paddle at 3 knots fairly easily for an hour (and I am not a paddling athlete).
A Main Point But my main point is, you would enjoy such a boat, I think. In medium air it will provide some fun, in light air it can take a passenger, but I recommend it as a solo boat unless you deck over the canoe hull almost completely, watertight). In light air.... you yourself can recall various bumpersticker proverbs concerning " is better than a good day at work..."
No Plans, Sorry As with my Monday boat, this boat had no plans nor was it "designed" except for some rough sketches and rough cardboard model making. I went by some commonsense, some constraints dictated by physics, and by what I thought looked right (having looked at a lot of sailing craft over the years). Some experience with the first proa, and many conversations with knowing and kindly people on internet boating groups helped out.
A small boat ought to be well designed, I agree, but other factors have powerful influences on the way a small boat behaves -- for example, where you sit, six inches here, six inches there, will alter trim and forces on the hull enough to change handling characteristicsw. By all means, do great design work, but if you don't have the skills, don't let that prevent you from trying.
But let's grind some French Roast, brew a pot, and have a look.
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Signing UpStep 1Beautiful Models
But not here. I did some sketches, roughed out a paper model, then cut and scarfed plywood sheets into two 2 feet by 16 feet sheets (topsides). I cut the stem and stern rake angles (a foot back from edge looked right) and then stared and stared before drawing rocker curve (the curve upward from the bottom -- bottom center in this hull -- toward the ends to set the hull depth and its location = center of buoyancy = helps the boat turn and has other interesting hydrodynamic implications).
Step 1 (Photo 1)-- Mock-up one inch to the foot scale model of the topsides (2x16 inches) out of cardboard, paper, or thin modeling wood.
Step 2 (Photo 2) -- Cut the stem and stern rakes after brainstorming them. These rake angles affect aesthetics, the buoyancy of the ends, how the ends interact with wave shapes (a surfing canoe often rakes the stern to match the typical wave shape it is embedded in so that the stern does not dig in and slow the rate at which you can turn the boat to avoid broaching), and waterline length when boat is heeled (for raked ends, it increases when a boat heels, but this is less of an effect for an outrigger cane than it is for a constantly heeled monohull sailboat; increased waterline increases hull speed).
I built a symmetrical hull to let me convert the boat into a shunting proa (check out Proafile Magazine on-line or Wikipedia "proa" to see good explanations about proas). if you are building a dedicated tacking boat, you can play with changes in hull shape to better suit your sailing regime. But now I am too deep into the theory of nautical design, where I cannot be your expert guide.
Step 3 (Photo 3) -- Draw the rocker line. Think really, really hard about what the rocker curve should be. Read books about it. Talk to people. Remember, rocker is pretty much permanent. You can change some things after a boat is mostly done (if you must...), but rocker would be the one you cannot change without sawing the bottom off the hull.
I wanted about 4 inches of rocker because it seemed good. More rocker = more load carrying ability (more buoyancy volume), easier turning, and slower speed (in some cases); less rocker means less load carrying,better tracking, harder turning, more potential speed (in some cases). But rocker curve is more complex than I am making it seem here. I used a tiny batten to draw the curve, and (obviously!) a full sized one for the full sized sheets.
Step 4 (Photo 4) -- Clamp the sheets together (both for model and full sized pieces) to double-check symmetry. The pieces should match, in other words. Trim as needed.
4A -- For the full sized topsides, now is the time to epoxy in the gunwales, stringers (stiffening longitudinals (but see the next step for more on this), and the chine log (the strip of wood inside the bottom of the topsides onto which the bottom of the hull will be epoxied). Any plywood-boat building book or essay will tell you about such things.
Step 5 (Photo 5) -- Attach the ends to form the basic hull shape. (a) Tape the model ends together (drill small holes and wire the full sized topsides; the topsides have additional requirements: gunwales, stringers, chine logs, and stem/stern pieces, all epoxied to the inner sides except for the gunwales -- see next step).
(b) Cut spreader sticks (easy) or bulkheads (harder) to design in the profile of the hull. Wedge them in and move them around to set up the maximum beam (at both top and bottom of boat) and the curve of the profile. I planned on a trapezoidal sharpie hull and used sticks.
(c) Eyeball the hull from all angles and move the sticks a little to achieve fair curves. Eyeball the hull a lot because you can still change its design easily at this point, but not so easily after the next step.
Step 6 (Photo 6) -- When you are happy, you glue in your bulkheads or cross-pieces.
Step 7 -- Measure, trace, cut, and attach bottom. (a) You flip the hull, (b) measure the stem to stern lengfth on the bottom, being sure to follow the rocker curve, (c) scraf plyuwood for the bottom, (d) lay on the sheet for the bottom and weight down, (e) trace the bottom shape on it, (f) cut out the bottom, (g) use thickened epoxy to glue the bottom to the hull, and (h) trim the edges of the bottom flush with the topsides; later you will round off the edge and overlap fiberglass to protect exposed plywood edges.
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MOD - i hope this place doesn't turn into a "look what i made" forum rather than a "look how i made this" forum, because this is one forum i love visiting often. in fact i believe this place is exactly why the internet is as valuable as it is today. plz dont let this place degen into a brag board.
Also, I don't see Instructables as necessarily having to provide complete details -- then it is not quite DIY, is it? Building should imply some personal creativity and exploration, else, why bother? I make exceptions for aircraft, rockets, nuclear reactors, and ejection seats, all of which should be built to spec. :-) On the contrary, I see no problem with a project write-up being strongly contextualized as "inspiration" to "copy with variation" or "copy with imporvement" or "take off from a new perspective after inspiration."