Building a Sailing Trimaran - Page 1


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August 26, 2006

Click me to enlarge This whole boat building thing got started with my buddy, Jeff Marquart, needing to move from here in North Carolina to Arizona for work. He was mostly through with building a Jim Michalak Toto (a double-paddle canoe), and rather than drag the incomplete project with him more than 2,200 miles, he opted to give the thing to me. So it began.

I finished the Toto in May of 2006, and it took until about August before I got the itch to build another boat. I have always been interested in sailing, but my wife has been opposed to us buying a small sailboat. She didn't say I shouldn't build one, though, so I jumped at the chance. The only caveat here is that she also said she would prefer if I only built boats that I wouldn't be able to buy otherwise.

Here is where the Jim Michalak Trilars comes in. There are no reasonably- priced production trimaran sailboats available here in the US - at least that I have found. There especially aren't any that are as lightweight as the Trilars and offer a way to remove the mast and floats (called amas by the Polynesian inventors of this style of craft) to make it double as a comfortable 2-person canoe. So, I ordered the plans online from Duckworks, and Jim Michalak sent me his plans by mail in a few days.

The main hull is a standard "Larsboat" design with the following additions: reinforced gunwales where the crossbeams (akas) are attached, a mast step and partner, a rudder, and leeboard fittings. My Larsboat main hull will be built from 4 4'x8' sheets of 5.2mm (~1/4") luan plywood. Here is where I pushed them together to draw the lines for where the panels will be cut out. I weigh them down in the middle with a marine battery and my drill bit collection for now; eventually they'll be joined with fiberglass tape.


August 27, 2006

Click me to enlarge The lines are drawn according to Michalak's plans, and I used a 6-foot flexible steel measuring stick to loft the curves. Here I'm cutting away at the panels with a circular saw. A good way to do this with minimal room for error is to set the cutting depth of the circular saw to just over 1/4", then place a piece of sacrificial plywood underneath the panel being cut. This way, I can make all the twists and turns I need, and the wood underneath will keep the bottom edge from chipping, while at the same time preserving the saw blade by not trying to cut across my concrete garage floor.


Click me to enlarge All the panels, decking, bulkheads, and temporary forms are cut out.


Click me to enlarge Here, the temporary forms have 3/4" wood sticks attached around the sides with wood glue. This will provide a backing to screw into when the hull is formed into shape.


August 28, 2006

Click me to enlarge The permanent bulkheads and transom are glued together with epoxy thickened with wood flour. These require a more permanent and waterproof adhesive, because they're going to be permanently attached to the boat.


Click me to enlarge All the forms, bulkheads, and transom are framed and glued in a single day. I'll be ready to glue the panels together next.


August 29, 2006

Click me to enlarge My young puppy, Jack, is admiring the neatly mitered corners of my forward bulkhead, now that the epoxy is totally dried.


Click me to enlarge All of the panels are ready to be joined with fiberglass tape. That's a long sheet of parchment paper underneath the panels, so there's no chance the epoxy can stick to anything but the wood and fiberglass I want it to. Martha Stewart would be proud!


Click me to enlarge After taping and gluing on both sides of each panel with fiberglass tape, all the weight I can find is sitting on top of the joints. Hopefully, there won't be any air air bubbles or any fiberglass that isn't completely wet out with epoxy.


September 1, 2006

Click me to enlarge Here we go - the panels are joined together nicely, and the forms, bulkheads, and transom are laid in place roughly where they're going to go when the boat is stitched together. As you can tell, Jack is performing a stress test on the port side bilge panel.


September 2, 2006

Click me to enlarge The side panels are screwed into two temporary forms amidships. As you might notice in the background, one of my bilge panels is being retaped because it cracked when I picked it up off the floor. If only Jack had stress tested this one yesterday also...


Click me to enlarge All the forms, bulkheads, stem, and transom are screwed to the side panels.


Click me to enlarge Here I am, sighting down the boat's centerline to make sure nothing looks funny.


Click me to enlarge A look from the stem down along the boat. Everything appears to be aligned pretty well.


Click me to enlarge Time to turn the boat and begin attaching the other panels. From here on out, it'll stay on sawhorses until the hull is sound enough to support its own weight.


Click me to enlarge The bottom panel is screwed in place, and the bilge panels have been stitched to themselves and the bottom panel. Since I rejoined the cracked bilge panel first thing this morning, it has had plenty of time to set up before using it here. I do my stitching with copper picture-hanging wire, available at most hardware stores for a low price. The benefit of using this over cable ties or other methods is that it can be tightened and loosened with minimal effort. With cable ties, the only way to make a fit any looser is to cut them and use a new one, and the holes required to fit them are much larger.


Click me to enlarge The bilge panels are now stitched to the side panels, and hull has its shape. Now, it's turned back upright so the inside seams can be filleted. Since today began with five loose (and one cracked) panel, I'd say a lot got done!


September 3, 2006

Click me to enlarge The inside seams are now filleted with epoxy and wood flour, except for small gaps where the wire twists come through. It's still plenty strong enough now to allow for removal of all the temporary forms.


Click me to enlarge Here, she's flipped over, the wire twists are removed, and the outside seams are filleted.


Click me to enlarge After filling in screw and stitching holes with thickened epoxy and giving it a good sanding, the outside seams can be taped. That's my buddy Jon Whatley on the support team today - he also built a Toto canoe at the same time Jeff Marquart did.


September 5, 2006

Click me to enlarge All the outside seams are now taped, with two layers on the bow entry. Under the bow is where I'm likely to run into a submerged obstacle at high speed, so I want to make sure I have lots of armor here.


Click me to enlarge Here is a piece of 9 oz. biaxial weave fiberglass cloth I will use to armor the outer hull. It looks white in color now, but once it is wet out with epoxy, it becomes invisible.


Click me to enlarge The outer hull is now fiberglassed. Submerged rocks and sea turtles have nothing on me now!


September 6, 2006

Click me to enlarge Once the epoxy has set up, the excess can be trimmed off with a chisel. That's my father in law in the background coming over to inspect.


Click me to enlarge Now that we're all cleaned up on the outside, we can start to focus on the inside. Time for another flip on the sawhorses...


September 7, 2006

Click me to enlarge Let's look at the floats for a minute to change gears. They are made from three 4'x8' sheets of 5.2mm luan plywood. Since they are 12 feet long, we need to cut one of the sheets in half and join each half to the ends of the other sheets, making 3 8-foot panels into 2 12-foot panels.

Here is my low-tech method for making long, square cuts across plywood: First, mark a 48" measurement from each corner of the piece (assuming it is square). Second, measure the distance from the blade to the outside guide on the circular saw. Third, mark this distance to the right of your 48" mark on both sides. Fourth, lay the board on top of a piece of sacrificial plywood on top of your work surface, and clamp a straight edge (in my case, my 6-foot measuring stick) to the board with the left edge aligned on your new marks. Last, cut away, keeping the saw guide flush to our clamp-on "fence."


Click me to enlarge Viola! We have two perfectly square pieces to attach.


September 8, 2006

Click me to enlarge Instead of drawing and cutting out the panels before joining them, I decided to do it in the opposite order this time to see which way is faster. Here, I fiberglass both sets of plywood sheets together in one pile. In between sheets, I use parchment paper so they won't also stick together.


Click me to enlarge While my new panels set up in epoxy and fiberglass, I reinstall the forward bulkhead in the main hull - this time permanently. As you can see, I had to use a piece of rope to hold the sides flush. The hull had warped down on the port side in the process of filleting and fiberglassing the exterior, so it took rope and clamps to pull it back together. When this dries, it will be incredibly strong; wood under tension is always stronger.


Click me to enlarge Now the new 12-foot sheets are dry, and they're ready to be marked up and cut for the floats.


Click me to enlarge Now that the forward bulkhead is secure, I can fiberglass the cockpit. This is done with 10 oz. fiberglass cloth for durability. Now, this section is fiberglassed inside and out.


Click me to enlarge While the cockpit fiberglass dries, I chisel out a small rectangle of wood just aft of the stern compartment bulkhead, being very careful not to cut through the outer layer of fiberglass. You can tell how thin the hull is at this point if you notice the light coming from my shop light underneath.

This is where my through-hull sonar transducer will be mounted. Since wood is too lossy a medium for sonar to work reliably, I remove the wood layer separating the transducer from the water underneath. Fiberglass conducts sound very well, so the transducer should work flawlessly with just a thin layer of fiberglass separating it from the water. This will be filled in with epoxy and the transducer later on.


September 9, 2006

Click me to enlarge Here I fiberglass the inside of the bow compartment...


Click me to enlarge And here I do the stern compartment.


Click me to enlarge Here are the side panels for the floats being cut out. These were cut using the same method that was used for the main hull. As it turns out, it is simpler and faster to join the plywood sheets before marking the lines and cutting out the shapes.




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