Building a Sailing Trimaran - Page 3

The epoxy is hardened and the deck coaming is secure. After I went through the trouble of clamping and screwing the coaming in place so it wouldn't snap off and shoot across the room like arrows, I read the suggestion that some builders of the Larsboat hull design found that attaching the coaming before attaching the deck was easier. Oh well, maybe I'll do a better job of reading ahead in the instructions next time.

Now that the centerboard trunk sides are firmly set in place, I put some strips of fiberglass tape along the inside bottom edge where the centerboards come down. This should give them a little more abrasion resistance if the centerboards rock back and forth while in use. In order to keep the tape from bulging inward and hardening in such a way to prevent the centerboards from going in to the slots at all, I put a 3/4" piece of wood between sheets of wax paper inside the slot. After the fiberglass hardens, the wood can be removed and the slots should be free of obstructions.

Fiberglass cut out and applied to the entire hulls of both floats. This will make them a little heavier, but pretty close to bulletproof when it comes to striking submerged objects at high speeds.

The lower wooden mast partner will be placed near the base of the mast to hold it in position. My mast has a "teardrop" cross-section, so I cut the center hole in this piece to match it. I fiberglassed both sides of it because it will need to be very strong and impact resistant - remember, an 18.5 foot aluminum mast gets jammed into this thing, and unprotected wood would probably get chipped away. Along with this mast partner, I will install an upper partner at the forward peak of the deck coaming and an aluminum mast step at the base. The mast will be held in place a total of three places near the bottom, and it will have two sidestays and a headstay. This should support the extra force exerted by 120 square feet of sails.

The main hull is brought outside to check the fit and balance of the mast before the lower mast partner is epoxied in place. I use a digital protractor to make sure I have the designed mast aft rake of 4.8° before marking the location of the lower partner and epoxying it in.

Apparently, what I'm doing outside is very interesting to the dogs!

While the epoxy dries on the lower mast partner, I chisel away the excess fiberglass which has now hardened on the floats.

The lower mast partner is set in place, and now I can measure and cut out the upper partner. First, I cut out the same teardrop shaped hole in the board to be used for the upper partner, and fit the mast through it. Then, I place the mast in the lower partner and clamp the upper partner rough board in place. With everything clamped down, I use the digital protractor and framing square to make sure I have the correct aft rake and to make sure the mast is centered athwartships. The board you see attached to the mast with bungee cords is there to allow the protractor to measure the mast angle of the mast even though the upper partner prevents it from contacting the mast directly. The 2x4 piece underneath the protractor is there to lift it up high enough to make an accurate measurement.

The upper mast partner is cut out and screwed to the coaming to ensure proper fit. Everything looks OK, so I thought I might pull out the floats and show off where the boat stands at this point, now that all three hulls would float and the whole thing is starting to take shape.

Both floats are fiberglassed on the outside, so they are now ready for their gunwales. I only have enough clamps to do the gunwales for one float at a time, so we'll start with the starboard float.

One float down, and now time for gunwales on the other. Once again, I use every clamp I own.

Now that the epoxy has set up, it looks like these gunwales on the floats will hold their grip. The sides of these feel very strong and rigid now.

Here, the sonar transducer is epoxied in place over the spot I chiseled out before.

The decks for the floats are fit and cut out, and the partial slots for the centerboards are also cut out. I don't cut out enough for the whole length of the centerboard trunks; I just cut out enough to allow the control levers to swing back and forth. Here, you can see how the centerboards will fit in their trunks. Screws are put in the deck at the stems and sterns to make sure they can easily be realigned to the same location when they're removed.

The locations for the hatch openings, fairleads, and blocks for the float decks are measured and marked.

All the openings for the hatches are cut and chiseled out of the float decks.

The float decks are then laid back on the floats, and checked to make sure the hatch locations still make sense.

With the much-needed help of my buddy Jon Whatley, we attached the deck coaming for all the hatches on the floats,

attached the hatch coaming for all the hatches,

fit most of the pop-riveted fittings to the mast and boom with the super-sized pop rivet tool,

and attached beveled wooden pieces to "level out" the locations where the stem fitting and bow cleat will be placed.

Here's a look at the floats with the newly-constructed hatches laid in place. Thanks for the help, Jon!

Here, I epoxy in a piece of wood backing on the inside of the transom for extra support for the gudgeons. I hold it in place by clamping a piece of scrap 2x4 on top of it with a piece of wax paper in between so any stray epoxy can't stick to my scrap piece or the clamps. I also epoxy in the battery support pieces on the aft side of the stern bulkhead. The small battery that runs the onboard electronics will be strapped in here.

The decks for the floats will be attached soon, so I wanted to get some pictures of how the insides of these look before I close them off. Here, we are looking from the bows back toward the sterns.

Looking from the float sterns back up to the bows.

Looking directly down the finished centerboard trunks. Neoprene washers and white grease will create a watertight seal around the pivot bolts when the boat is finished.

A coat of epoxy for the underside of the float decks for moisture-proofing, and some pieces of fiberglass tape for abrasion resistance and strength where the compression latches will pull up against them.

Fitting the aft deck to the hull. The outline is traced out from underneath, then it will be cut to shape.

One last coat of epoxy has been put inside the stern compartment for waterproofing. Here is one last look before it gets closed in under the deck.

The aft deck is now cut to shape and fiberglassed underneath for extra strength in holding the through-bolted hardware in place.

The fiberglass on the aft deck has set up and I chiseled away the excess material. It will be ready for installation on the boat after it gets one more coat of epoxy on the underside.

The float decks each get one more coat of epoxy on the underside also, and I added wood pieces at the bow and stern to hold screws for cleats if I opt to install them in the future.

Installing the aft deck. As it turns out, shotgun shells, steel clamps, and small anchors are good weights to use for this...

Installing the port float deck. Same drill: use plenty of evenly distributed weight.

Hours later, the aft decking is dried and ready to go. This concludes the decking work on the main hull!

The port float deck has hardened in place, and now I apply epoxy and switch the weights to the starboard float deck (I also swapped their positions on the sawhorses so they'd be easier to work on).

Here I am, having a beer and petting Jack while visualizing the great sailing performance of what I'm building.

Clamping and screwing together the forward crossbeam saddle. This will sit on top of the peaked forward deck to hold the crossbeam in place.

Jack helps remove some of the wood chips and sawdust from the shop floor by rolling around in it and carrying it off on his back. What a dog.

Here I am checking the measurements on each side of the crossbeam saddle before I glue it together.

One last check of the crossbeams to make sure they fit and look right when seated on the boat.

The epoxy has set and everything looks like it still fits fine.

The forward crossbeam saddle close up. The two holes are there to allow for moisture to escape from what would otherwise be a sealed-off empty void.

Both crossbeams are now fitted to the center hull, and the holes have been drilled for the bolts that will hold them in place when the boat is assembled.