Thursday, September 27, 2007

Mast Assembly Details

I just completed the assembly of the mast this afternoon when I glued on the final side wall to close up the hollow box. I counted a total of 43 separate pieces of wood in the mast assembly, counting the scarf sections for the long pieces. It's definately not the work of a weekend or couple of evenings, but it went reasonably fast and everything went together smoothly. The photos below show a few of the details and the assembly sequence and methods I used.

The mast head has a built-in crane for the main halyards and internal wooden sheaves for the jib halyards, separated by a central divider. I built this assembly as a separate unit, so I could insure that all the exposed areas around the sheaves were well-coated with epoxy. In addition, the bearing surfaces of the sheaves, which are made of mahogany, are glassed over and then coated with an epoxy and graphite compound for a smooth, durable surface. You can see the black graphite epoxy coating in the photo below:

The masthead also has solid blocking around the crane area. To get a wiring conduit through this area I built the blocking with a channel just wide enough for it to pass through in the center. The conduit is flexible plastic irrigation pipe, with an I.D. of 1/2 inch. One of these in each mast half should give me enough space for a VHF coax, 12-volt circuits for a masthead tri-color and anchor light, and a cable for a Sea Me active radar reflector.

At the foot of the mast the conduit exits the side walls just above the solid wood packing above the mast heel. This wood packing at the foot is to allow for long screws to mount halyard clutches and blocks. I routed the wiring out the side walls since the aft side of the mast is occupied with the clutches and the forward side is taken up by the mainsail downhaul.

To keep the conduit out of the way during the final assembly, I epoxied in these tiny slats of 6mm ply. These weigh next to nothing and were simple to make. I ripped a couple of strips of the ply to the right width with 45 degree angles on both sides, then chopped them up into 3/8" wide pieces. They fit perfectly, the ends dipped in epoxy and simply laid in place to dry.

The slats also make it easy to pack aluminum foil into the mast halves by tucking it under them so it too does not move when the pieces are put together for lamination. The foil inside is supposed to be a passive radar reflector. I don't know how effective it will be, but it can't hurt anything and it was certainly cheap.

Here is the final assembly. I now have a straight, hollow box section mast. When the epoxy cures it will be ready to cut down to eight sides, then sixteen, and finally round. But that will be a job for next week.

Wednesday, September 26, 2007

Keeping it Straight

No matter how carefully you select the wood, with eight separate staves more than 26 feet in length, there is bound to be some tendency for some of them to bow or spring out of true, due to natural crown or grain patterns. The only way to insure that you get a straight mast is to laminate the sections with a form that is dead level and absolutely straight. I had already glued the triangular wood fillets to the two mast halves using the straight edge of my workbench. This worked fine, but one of the halves still had a bit of crown in it after removing the screws used to glue in the fillets. It's a simple matter to get it back in line, as long as you have a straight form to clamp it too. I built a lot of straight and curved forms recently while working on the pergola project in Florida, so I figured it would work fine for my mast as well.

The first step was to screw down a platform of 2 x 4s to the work bench, to elevate the mast sections clear of the bench so that bar clamp jaws can fit under them. The bench was already level, but after screwing down the platform boards I checked them all with a spirit level and with a taunt line. The ends were also aligned with the taunt line so that when upright blocks were screwed on at a right angle they were all dead in line. This form allows clamping in two directions, vertically and horizontally, which is necessary when glueing the mast laminates together to be sure all joints are closed up with no voids in the glue line.

In the plans for the Tiki 26 mast the method of assembly is to use rope lashings to pull all the parts together. This is assuming most first-time boatbuilders won't have enough clamps of a sufficient size to assemble the mast. The rope method works, and I used it on my Hitia 17 mast, but with the weather as hot as it is here, limiting the working time of the epoxy, I didn't want the stress of trying to assemble all four parts of a 26-foot mast at one time. In addition, this mast will have wiring conduit inside, as well as aluminum foil for a radar reflector - more stuff to worry about keeping in line while trying to hold and wrap four long, springy pieces of wood. Since the mast diameter is only 5 inches, relatively inexpensive 6-inch bar clamps work just fine for all the assembly steps. I used 40 of them, and this was plenty adequate for close enough spacing to close up the parts. Instead of assembling all four parts at once, I started by glueing one side wall to the aft wall, using the form to keep it all in line. This worked out perfectly, and when the clamps were removed this morning, this half of the mast was rigid and straight with no tendency to bow.

Decks As Designed

Work on the port hull is moving along now that I've resolved the deck modification issue. One reason I decided to scrap the idea of raising the decks is that I really like the deck lines as designed. To me the amount of camber is just right, combined with the strong sweep of the sheer.

I still have work to do inside the hulls around the bunks and the stem and sternposts before decks can be installed, but deckbeams for both hulls have been made and installed in the port hull. Notches for the stringers were first cut in the beams separately, then with beams clamped in place the notch area was removed from the plywood of the bulkheads with a flush-cutting router bit. In the photo below the finished foredeck beams are clamped in place with epoxy.

I've also cut and test-fitted the deck stringers for the foredeck. I've increased the width of these slightly for more stiffness, and added extra stringers in the main foredeck area just forward of the mast beam - an area of the deck that gets a lot of traffic. I've been on board Tiki 26s with springy decks. I think it's worth it to reinforce these so that there is no flex. The center stringer runs all the way from the forward cabin bulkhead to a notch in the stem post. After the deck is glued down, it will be cut away in the opening of the forward hatch. The other two long stringers to port and starboard terminate at the buttblock area of the upper hull panel, and will be supported here by a small cleat glued on the inside of this buttblock.

Sunday, September 23, 2007

No Raised Deck

I've decided to scrap my idea mentioned in the recent post about the raised deck modification. I think this modification could work and could be made to look good, but I've decided the slight gain in interior room would not be worth the extra complications in construction. Every change to a design has implications beyond the immediate modification, and a change such as this would involve other areas of the boat that may delay the final completion and may have an adverse effect on performance. If I were building two Tiki 26s side by side, I would like to try this modification on one of them and see how it works out. As it is, I just want to get the hulls built and decked and get sailing as soon as possible.

To make up for the three-inch height increase of the bunks, I am simply raising the cabin tops by a corresponding amount, actually four and a half inches, keeping the same angles and lines. This will give adequate sitting headroom in most of the cabin area. The only change in shape will be the cabin roof, to which I might add a slight camber similar to that of the new Tiki 8M design. I also plan to make the companionway hatch smaller so that it does not occupy the entire forward part of the cabin roof when in the open position. In this space forward I plan to fit an additional hatch in each cabin, for better ventilation. For these I may use standard manufactured deck hatches that can be adjusted at a varying angles and have insect screens incorporated.

I've been busy today fitting deck beams and making the deck stringers, as well as adding the upper bulkhead sections on to the existing bulkheads where I had left them off while pondering the deck modification. Things will move forward quickly now with the first hull now that this issue is resoved and all I have to do is build. The mast is also coming along. I'm working on making and fitting all the various bits that go in the crane and foot, as well as channels for wiring conduits inside. No new photos to post today, but I'll have some later this week.

Wednesday, September 19, 2007

Mast Building

The Tiki 26 laminated hollow mast is well-designed and simple to build compared to most wooden mast building techniques. There are a lot of parts to cut and assemble, but each step is straightforward. The construction begins with preparing the wood by ripping it to width and then scarfing it to the required length. All scarf joints are cut with a minimum 12:1 ratio for strength. Below are the scarfs for the two main half panels. These are 3/4" thick, as that is the required wall thickness of the finished spar.

Inside the mast are triangular fillets of solid wood that hold the four outer plates together and provide enough wood inside to maintain the wall thickness when the mast is cut down to the round section. These fillets are cut on a 45 degree angle from two-by fir stock that was first scarfed to full length.

To establish a straight line and compensate for any natural crown in the mast lumber, I first clamped the halves to the bench and lined them up with the straight edge of the top surface, double checking with a taunt line. The first fillet is glued in place, and when this joint cures the laminate helps hold the plank in line.

All of the fillets are now glued in place on both halves, and everything came out straight and true. The next step is to make and install the many parts that make up the masthead and the mast foot.

Below at left is the mast heel that fits inside the spar at the foot and pivots on the mast step that will be laminated into the top of the mast beam. The step and heel are made of laminated mahogany. To the right are the ply parts that make up the mast crane.

Sunday, September 16, 2007

Mast and Beams

I've decided to go back to my original plan of laminating the mast before I remove my 26' long workbench that is in the way of assembling the second hull. Although I am anxious to get the second hull built, it will be more efficient to make use of the workspace I have to glue up the mast. The finished stick can then be hung from the rafters out of the way until the hulls are completed. Hopefully, I won't need a long, flat bench again for any other parts of the boat. All of the stringers are made for the second hull, and I finished assembling the topside panels with their stringers installed last week. The mast is a fairly big project, because of the many components. The first step is to cut the stock to the required widths, then scarf the pieces to get the length. The rough stock shown below is 16' lengths of Doug fir, in 1x6 and 2x6. The 2x6 pieces have already been ripped to 2" widths. These will be cut on a 45-degree angle to make the interior fillets after first scarfing them to full length.

Before the mast lumber arrived I finished assembling the topside panels for the second hull. Shown below is the last one, the upper stringer being glued on by clamping it between the panel and the flat bench. These panels can also be hung out of the way while working on the lower hull assembly.

Back at the garage workshop this weekend, I'm making steady progress on assembling the crossbeam components. First the stringers that stiffen the vertical webs, and then the floor panels, to which the webs are laminated. Like the mast, these beams have many parts and just getting the all put together will take many glueing operations. It's good to be able to do this in another location so these parts are not in the way of building the hulls.

Tuesday, September 11, 2007

Raised Deck Modification

I've been working on the design of a modification I've been contemplating since before I decided for sure to build the Tiki 26. I think the basic design of the boat as drawn is great, but like many owner/builders, I want to fit my boat to my needs and requirements and I think minor modifications within reason can be done without detriment to the design's proven capabilities.

As I've stated before, I wanted to build the smallest boat that would work for my intended sailing, and for me the Tiki 26 is it. A Tiki 30 would have more interior room in the cabins, but at the expense of much more time and cost to build, as well as more difficulty hauling out and demounting for trailering. Sitting headroom in the cabins is all you can expect on any of the Tiki designs short of 38 feet, and the Tiki 26 has this. What I wanted was a bit more elbow room inside as I am 6'2", and one way I saw to accomplish this was to build a "raised deck" version that would allow me to also raise the bunk levels a corresponding amount to gain a bit more width there due to the flare in the V-hulls. One famous Wharram catamaran that was modified to an even greater extent to gain more interior room is Rory McDougall's Tiki 21 Cooking Fat, which he sailed around the world. The extra volume created by the raised decks contributed a lot to the ability of such a small catamaran to handle the conditions of the open ocean, adding reserve buoyancy where it was needed.

Although I did some sketches and even built a rough model before I began building the boat, I knew I wouldn't be able to determine for sure how the raised deck modification would work out until I had a hull built. I left my options open by cutting the cabin bulkheads separately and leaving extra material above the sheer on the installed bulkheads. I went ahead and raised the bunk levels by 3 inches, knowing that I could make this up in the raised deck or if I changed my mind, by simply raising the cabin tops 3 inches, which many Tiki 26 builders have done. Since I've been away from the boat for awhile in Florida, thoughts of these modifications were weighing on my mind quite a bit and I decided yesterday to go ahead and start working out the details to see if it's going to work.

The first step was to cut the extra bulkhead material above the sheer level to a slight inboard angle, so that the new side deck panels will be cambered in by a few degrees. I then made up some Doug fir stringers 1 3/4" by 3/4", the same dimensions as the other stringers in the hull, and sprung these in place against the bulkheads to get a fair curve. Maximum height above the sheer is 3 and 3/4", decreasing to 2" forward at bulkhead 6 and aft at bulkhead 1. The raised deck section will begin with the this 2" bump in height just behind the front crossbeam, so that the transition will not be noticeable. It will end 4 feet aft of the cabin at bulkhead 1, where it will blend into the rear trampoline beam I will be installing there. The new stringers for this raised deck panel will be on the inside top edge of the panel, let in flush with the cambered edges of the bulkheads. The decks themselves will have the same camber as in the plans, and the cabin bulkheads will follow the design lines, beginning at the top edge of the raised deck sheer. The mast and aft beams will fit in their chocks atop this raised section forward and aft of the cabins, with all loads transferred to the reinforced hull sections below at the true sheer. Beam lashing chocks will be located below the hull sheer as designed.

Although I'm not ready to begin permanently building these raised decks just yet, I've mocked it up with stringers clamped into place and the cabin bulkheads clamped above them. It's hard to visualize the appearance of the decks from these photos, since the tops of the forward bulkheads are still straight and do not show the graceful deck camber that will be there, but you can see the lines of the raised deck section at the outside.

This is a view at the stern showing how the section will terminate at bulkhead one behind the cabin. A rear trampoline beam will be mounted on the lower section just aft of the transition.

Here is a view of the raised section with pattern material in place. You can see the slight inboard camber here. This seam will of course be faired and glassed into the outboard sheer stringer below it.

Saturday, September 08, 2007

Getting in the Groove Again

I'm back at it now after my seven week interlude in Florida. It's amazing how disorganized things can become after even a short interruption of progress. It's not easy having tools and supplies as well as parts of the boat divided between two different workshops over an hour apart. I've spent much of my time since I've been back just reorganizing and planning for the next phases of the project. I've been shopping for tools and supplies, and making decisions about modifications and outfitting and equipment that will be needed for the finished boat.

The next major phases of the build will be the second (starboard) hull, which will come together in the boat shed next to the first hull, and the connecting beams, which I am building in the garage shop at my girlfriend's house. Despite the inconvenience of moving tools back and forth between two locations, the boat will be finished faster if I can work on something every day.

The crossbeams for the Tiki 26 consist of numerous Doug fir stringers that are laminated to the vertical webs and floor panels of the beams. It takes a lot of clamps to glue up these assemblies, and though I'm always adding more to my collection, I don't have enough to do all these at once, so like everything else in the project, it is a process.

In the boat shed I have the two complete hull panels for the starboard hull assembled and fitted with the lower stringers. These need sanding again and a second coat of epoxy and then they will be ready for assembly. Before I can put the hull together though, I need to tear out the 26' long work bench that is in the way. I don't want to get rid of it before I finish all the long hull parts, so today I cut the scarfs and joined the upper topside stringers. Next, I will assemble the topside panels for the second hull and glue on these stringers so that they will be ready to install when the lower hull is complete.

The port hull was sheathed with 6oz. fiberglass before I left to work in Florida, but there were areas where the weave was still not completely filled. I sanded the entire hull again today and applied another coat of epoxy to one side. It's really starting to look even and smooth now. Tomorrow I will flip it in the slings and coat the other side again. After this epoxy coat and more sanding, the first hull will be ready for the fairing and filling process.

Wednesday, September 05, 2007

Back From Florida

I'm finally home and ready to begin work on the boat again after seven weeks of working in Florida, as I mentioned on my previous two posts. The job was interesting and certainly contributed much to the funding of my Element II project, but it's nice to be back on my own time and I'm looking forward to boatbuilding now that fall is almost around the corner and the best weather of the year will soon be here.

I've spent the last couple of days since I returned catching up on neglected business and making lists of materials, parts and equipment I will need to finish Element II. I plan to order much of this stuff this week so that everything will be on hand, and hope to have no further long interuptions of my work on the boat at least for the remainder of the year.

For those who are interested in the extravagent waste of fine teak lumber this project in Florida consumed, I've posted a couple of photos below. These were taken in the shop as the first half of the massive pergola was preassembled. After this preassembly, it was taken apart in seven large pie-shaped sections, moved to the house site, and lifted with a crane to the top of the 10-foot stainless steel posts to which the woodsections are bolted. Brickwork around the posts will follow, and then all this fine wood will be covered in flowering vines or some such vegetation.

This photo shows only part of the first half of the pergola with top purlins installed. The curved beams are 5"x8" laminated teak. Purlins are 3"x6". Outside diameter is 56'. Inside diameter is 38'. The other beams on the table in the middle of the assembly are for the second half. The reason that this job took so long is that it is not built to ordinary outdoor carpentry standards. All joinery is to fine furniture grade, with every cut made oversize and hand sanded to a perfect fit. Every surface of every piece of wood in the project was sanded to 80, 120, and then 150 grit, and after final installation on site will be taken to 180 grit.

This photo shows a small section of the outside radius, so that you can see the shape of each purlin. These ends were cut on a special jig we built for the bandsaw, and dadoes were cut to fit over the beams. All hardware is countersunk stainless steel bolts and lag screws, sealed with custom-fitted teak plugs.
We had the first half installed and the second half mostly fitted when I left this past weekend. I regret that I didn't get to see the entire project to completion but had already stayed a week longer than I planned. I should get some photos from David (owner of Boatsmith, Inc.) in a couple of weeks or so of the final installation. David, by the way, is a bit of a Wharram enthusiast as well, and I think the fact that I had built a Hitia 17 many years ago impressed him enough to hire me when I first met him back in 2001 while living in Florida. He's been talking for years of building a Wharram, probably a really big one. He likes the Tehini a lot. If this happens I may be back in Florida from time to time helping him out.