Introduction: The Snail - a 9ft Pram
The dream all stared at my first Wooden boat festival, an event that is on my must do list every year now. Out of all of the majestic schooners and wooden artisan takes on modern performance dinghies, the one that caught my eye was the lowly Minnow. The Minnow is a 12ft plywood pram built out of 4 sheets of plywood and some ground tarps. She boast that she complected the first leg of R2AK, a race from Seattle to Alaska. I knew that day that I would build a boat. The opportunity to do so emerge my senior year of High school where I was allowed to have a self lead year long project. I know how to sail and I know some basic boat design but I am no means an expert or even well read. The following is my experience with struggling with this little bugger and hopefully a guide for you on what not to do.
The picture above is not the Minnow nor is it the Snail. It was the boat that gave me a strong enough argument with my teacher to approve the project.
Step 1: Gathering Ideas
Pictured above is a fleet of Optimist dinghies and some cousin of an Opti. I teach sailing to kids in the summer and the Opti is a solid little boat that we used for the younger kids. I used the Opti's take on the pram design but scaled up for my basic vision of the Snail. The simple single sail, sprit rig design of the Opti was also an appealing steal becuase of simple spar structure and (I assume at least) strait forward balancing.
Step 2: CAD Isn't That Bad
I used Rhino and V-carve exclusively for the designing of the Snail. I started the drawing by laying out 2 planes of parallel lines that represent the distance gunnel to gunnel. I then Curved trough the ends of the lines and connected them to create panels. All of the panels was then flatten out and organized to fit on to 4x8 sheets of plywood. Each 4x8 section was then put into V-care to be cut out on a CNC router.
Step 3: It's CNC!
I started out by cutting a quarter scale model (pictured above). After zip tying all the seams together I deiced I was happy enough with it to do the full scale. I made the cuts on 5 1/4 inch 4x8 sheets of ACX plywood using a 1/4 router bit. Also pictured above are the panels lied out after being cut.
Step 4: Binding the Hull Sides
Due to the limited amount of material the side sections of the hull as well as the fore section of the bottom of the hull had to be cut in half to fit onto the material. I started the process by laying down a sheet of plastic on a scrap 2x4 that was on the table. Then I butted the 2 sheets and applied 2 part epoxy to the joint and area around the joint. I finished it of by laying down another sheet of plastic and a 2x4 and then finally screwing through the wood and plastic sandwich.
Step 5: Tying It All Together
The next step was to set the panels in place to be later glued together. I drilled 1/4 holes about every 8 inches down the length of all the seams. After the holes where drilled I threaded zip tie between correlating holes. I repeated this till all of the panels where snugly pulled together.
Step 6: Peanut Butter, Resin Time
After zip tying them together I used a bit of 2 part epoxy to attach the panels enough that they could hold them selves together with out the support of the zip ties, I pulled out the zip ties and trimed the outside of the seams with a jigsaw. After that I made up a big batch of peanut butter (2 part epoxy mixed with saw dust) and coated and sealed up all of the seams.
Step 7: Beam Me Up...
With the peanut butter set, the snail was starting to firm up but is far from the rock solid I'm looking for so I added some supports. I peanut buttered a piece of wood across the beam of boat which is keeping the sides from flexing. I also used 2 strips of 1 inch cedar down the length of the rail to create a gunnel as well as adding cedar to the outside of the bow and stern. I also added 2 strips a bit aft of the beam running vertically which can be seen in the next step.
Step 8: "I Sheath My Dagger"
The next step was putting in a dagger board box. I used some 1/2 inch plywood to make the box. I cut a hole in the hull with a jig saw and then resined the box to the hull. I then filled the gap between the hull and the box with silicone caulking. After screwing the wood running across into the box the boat stiffened right back up if not more then before. I was scared I would loose some structural integrity by cutting that beam that was fitted perfectly but it worked out. Adding the box made a notable difference in reducing the amount of "oil canning" in the hull.
Step 9: Enter Sand(ing)man
The snail at this point was looking pretty rough (and still does) so we carried her down from the loft and put her outside. I sanded the gunnels until they matched and transitioned smoothly into each other. I also heavy sanded the seam on the bottom of the hull that connects the fore and aft sections of the hull as well as all external seems. An angle grinder (my third favorite tool currently) with a wire brush disk ate through the peanut butter like a fat kid during recess and made the Snail seem a little more presentable, now that her seams where smoothed out.
Step 10: Glass, Glass, Glass! It's Time to Resin the Glass.
I started out by glassing the seams of the hull panels that weren't reinforced by the gunnels. After that I used a thicker fiberglass sheet to glass the bottom of the hull. I used 5 strips and layered them on each other the length of the hull. For the process I would start by pouring a pool of resin and then would spread it over the area intend to be glassed then I would lay the glass pour again and repeat.
Step 11: Going Foward
This is my current progress with my Lil' Yachty as of the first semester. Next semester I will be able to work the boat 12 hours a week compared with my 7 hours a week with my old schedule. In that time I am planning on cleaning up the glass, adding benches, coating and painting, make boards and a tiller as well as make spars and cut a sail and a number of other smaller things that could make this thing seaworthy. Check back in June to sea (punny) how this thing turns out.
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