Thursday, February 21, 2008

Frames for the Portlights

While I was in Florida working with David Halladay on his Tiki 30 project, we discussed a lot of details in the fitting out of our catamarans and tossed ideas back and forth. David spends a lot of time working on interior and exterior carpentry projects for modern, high dollar motoryachts, and consequently has some methods and techniques beyond the basics shown in the Wharram plans for these boats.

One area that he feels can stand some improvement is in the installation of the fixed portlights on the outboard sides of the cabins. The plans show Lexan ports cut to overlap the edges of the openings in the plywood, and fixed in position on a bedding of sealant with small machine screws in holes drilled along the edges of the Lexan. This works fine and is seen on many types of vessels, but David felt it is a bit dated and doesn't look as clean as a more modern installation without fasteners. In addition, Lexan and wood expand and contract at different rates in temperature fluctuations, so the holes must be drilled larger than the screws or the panel can crack. A better method that he often uses for installing portlights is to either create a lip in the cabin side if it is thick enough, or add a ring frame on either the inside or outside of the portlight opening so that the Lexan panel can be mounted flush in the opening. This will be easier to visualize later when I have the actual Lexan and the cabin sides are installed, but the photos below show the process for making these frames.

The ring frames are made of 6mm ply, same as the cabin sides and the thickness of the Lexan that will be used. Since I had already mocked-up one cabin side on the port hull and had already cut the openings for the portlights, I was able to use the cut-out parts as templates for the ring frames. The Lexan will be cut slightly smaller than the existing openings in the cabin sides, to allow for some expansion, the frames will overlap the opening and the Lexan portlights by 5/8", making them a total of 1 1/4" wide.

Below is the sequence for making the frames for the smaller portlight at the forward end of the cabin. I started out by marking a line exactly the size of the opening on a piece of plywood to be used as the pattern. In the photo below, you can see this as the heavier centerline in the middle of the pattern frame. Outside and inside perimeter lines were scribed 5/8" on either side of this central line and the pattern was cut out to this line with a circular saw and jigsaw. The actual cuts were made 1/16" from the line and then the excess material was sanded off with a belt sander on the outside and by hand with sanding blocks on the inside. Below you can see the tube of caulking that I used to sand the inside radius. This was just the right size when fitted with a sheet of sticky-back sandpaper.

When the pattern was cleaned up and trued to exactly the lines and the curves were fair, I then temporarily tacked it to the first workpiece with a few dabs of glue from a hot glue gun, to hold it in position for routing.

Making exact duplicates from a pattern like this is easy with a router fitted with a straight bit with a guide bearing, as shown below. Although you can use a regular flush cutting bit with the bearing on the bottom, I prefer the top bearing kind, as you can better see what you're doing. This bit is long enough to cut more than one frame at a time if they are stacked, but I wanted to do just one first to make sure it was correct. There will be a total of four frames for the small portlights and four for the larger, aft ports, since I want to have both an interior and exterior frame for greater security. This is not really necessary with modern sealants, however, and many such ports are put in with just the sealant and an interior frame, resulting in a cleaner, flush exterior surface. My exterior frames will blend in nicely though, as they will be filleted and glassed right along with the rest of the cabin side and painted the same color.

Here's a view from the bottom showing the pattern-cutting router bit doing its job. For small parts of thin material such as this, I like small one-handed trim routers.

Below is the finished result. The piece of wood under the frame is the pattern for the Lexan port, and gives a hint as to how the actual port will look with the ring frame over the window.

Bunks Ready to Go In

A couple of days of good weather allowed me to finish up all the details that were holding up the installation of the starboard bunks. The final frames for the access hatches were fitted and laminated in place, and two coats of epoxy applied to all the bottom surfaces. Here you can see these parts curing in the sun curing outside the shed.

The structural and cosmetic fillets were also finished in the storage compartments below the bunks. A final clear coat of epoxy will go on over all this before the bunks are glued in place.

Here the finished bunk panels are in place, but not yet glued in. I had to be away for a couple of days and will glue them in when I return after the weekend. On Saturday I'm going to New Orleans to pick up what I hope will be all the plywood to finish the rest of the boat. This includes material for the cabin sides and decks, and the cockpit. Everything else requiring plywood is done.

Other details besides the under bunk areas included finishing up the fillets in the bow and stern buoyancy compartments and installing the plywood web brace, shown below, in the bow. In these areas that will be sealed off and out of sight, I'm using a filleting mix consisting of wood flour, silica, and phenolic microballoons. That's why you see the reddish tint. These fillets are easier to sand and smooth than the wood and silica blend I'm using in the parts of the boat that will be left unfinished or varnished. I'll also use this phenolic/silica mix for exerior fillets and fairing where everything will be painted, as it is much easier to sand to a feather edge.

Sunday, February 17, 2008

Crossbeam Fairings and Reinforcements

There are still many details to finish on the crossbeams, mainly the exterior fillets and the fairings. Before installing the fairings I wanted to shape all the edges of the Doug Fir stringer sections to a consistent radius. This was done using a router with a 3/8" radius roundover bit. In the photo below you can see the radius on every corner, including all four corners of the top plates and the exposed corners of the bottom plates. This radius will help protect the beams from damage by eliminating sharp corners that can be easily cracked or broken if something hits them. It will also allow for easier fiberglass sheathing, as I plan to glass over all the exposed surfaces of the beams.

The transition between the plywood webs and floors of the beams is also eased with a concave radius formed by a nice, wide fillet that is both cosmetic and structural. It takes a surprising amount of thickened epoxy to make all these fillets on the beams, as there are so many exposed corners that require them. All in all, building the beams for the Tiki 26 is a substantial project; even more time consuming than building the mast. It would be quicker to skip the fiberglassing step, with all this preparation it involves, but for maximum longevity this is important. One thing I don't want to have to do is replace major components like the beams sometime in the future because of rot or damage that could be prevented by these extra steps.

Below: All corners have been rounded and exterior fillets started.

At this stage before the fairing goes on, there are also extra reinforcing parts that must be installed on the mast beam, which will bear a much greater load than the other two. Here you can see the top plate doublers that have been glued on in the area of the inner hull gunwales, and the vertical compression struts that connect the top and bottom plates in these areas and at the beam center point, under the mast step.

After the epoxy cured and clamps were removed from these parts, the fillet under the aft edge of the top plate was made. All these fillets will be sanded and touched up as needed until they are smooth. When glassed, faired and painted, the beam parts will hardly be recognizable as wood, but will instead look molded out of fiberglass or plastic. The smoother they are, the less the possibility for moisture to hang around and cause rot.

I did the cutting and fitting of all the beam front fairings this morning. When they are installed the bottom edge will be shaped to match the leading edge of the beam floors. This corner will be filled with thickened epoxy and then rounded off to match the radius of the other corners.

The first step in preparing the fairings for installation is to coat the inside with two coats of epoxy. Here the first coat is drying while the parts are spread across the beams, which also have fresh epoxy fillets curing. This is where I left things at the garage shop this afternoon. The weather is supposed to be good for the next three days or so, and I will be back at the boat shed working on the hulls as much as possible.

Monday, February 11, 2008

Back at the Starboard Bunks

With renewed inspiration from helping David on his Tiki 30, I was back at work on my starboard hull today, after first waiting for it to warm up a bit outside from a low of 35F. Working in south Florida this time of year was nice, with highs in the 80s every day I was there. If I had those conditions and some helpers like David's guys I would be done in no time. Now I'm back to mixing my own epoxy and and doing eveything that has to be done, from reading the plans to sharpening tools and ordering supplies - a true one man operation.

Today I worked on fitting all the bunk stringers that support the access hatches and made the final decision on the size of the opening in the main companionway area of the starboard hull and the placement of the portable head. The bunks are almost ready to go in after I finish detailing the floor and bulkhead fillets under them and getting a second coat of epoxy on all the surfaces below them.

In the photo below you can see the forward end of the stringers for the bunk section in the companionway area. I borrowed the technique used in the Tiki 30 plans for letting in the supports by cutting a 45-degree notch in the supporting bearers to receive a matching angle at the ends of the stringers - simple and strong.

Here the bunk section is temporarily laid in place over the stringers, with the portable toilet in postition against bulkhead 3. This is the only placement that will allow it to fit under the bunks and still be usable without moving it. A sliding wooden lid will fit over it when not in use, serving as a seating area facing aft, where there will be a chart table and navigation instruments.

A view of the bunk sections through the inspection plate opening in bulkhead 1, with stringers epoxied and clamped into position.

Build Comparison: Tiki 26 and Tiki 30

In my last post here I mentioned that I was going to Florida for a few days to help my friend, David Halladay and his company Boatsmith in the intial assembly of a new Tiki 30 he's building as a spec project. Most of you who follow this blog have probably been following his progress on Pro-Built Tiki 30 as well, and have seen the photos I posted last week while I was there. If so, you know we made remarkable progess in the four days I was there, and I'm sure this pace has continued today as I was back here in Mississippi, working on my Tiki 26 again. With the right crew, a spacious shop to work in, and lots of machine tools to handle parts, building a Tiki 30 is not that big a deal. But for one person working alone as I am doing on my Tiki 26, I think there is a significant difference in the ease of construction between these two models. Remember that the 4-foot difference is just an illusion. A Tiki 30 is a lot more boat to build than a Tiki 26. Although I have no doubts that I could build one singlehanded, I knew from comparing the plans back before I made my decision to go with the Tiki 26 that choosing the 30-footer would have considerably delayed my launching date.

Below you can see the two hulls and the eight of us that put them together and completed all the keel filleting and glassing as well as bulkhead fillets and fabrication of many of the other parts in just four days. For one person working part-time and alone, the amount of man hours we put into the project to get this far would stretch into weeks. As you can see here, the hulls are much deeper than those of the Tiki 26, and will look even bigger with the topside panels on.

Another photo that illustrates the depth of the hulls and the height of the bulkheads. The Tiki 30 is a deep boat, but in this size there is still not standing headroom in the cabins, and the Tiki 26 offers full sitting headroom, so there's not much you can do in between sitting and standing when you're down below.

From a construction standpoint, one thing that makes the hull assembly and set-up much more difficult is the addition of the long, low aspect keel that has to be fitted between the lower edges of the hull panels. This keel assembly must be lined up just so or the hull panels will not open correctly when spread for inserting bulkheads. The keel backbone is also slotted to receive the bulkheads, and getting all this together while it's held together with wire and temporary screws requires some patience. Lots of tweaking and adjusting is necessary to get everything to fit correctly, and then once the hull is upright and bulkheads are in place, it has to all be locked down with braces to keep everything lined up and level until the epoxy fillets can be made. This was hard enough even with several people, but would take awhile to do alone. As James Wharram states in his design book, the Tiki 30 and 31 are about the largest hulls of this shape that can be reasonably built in the stitch and glue method. That's why in the initial phase the Tiki 38 is built upside down, so that the lower hulls are easier to line up and keep straight.

So did I make the right decision to chose the Tiki 26? Yes, I think so. It will give me most of the capability of the Tiki 30 for less money and for a smaller chunk of my life dedicated to building it. If I could just write the check and have a crew like David's put together a brand new boat for me, I might consider going larger, but as one who will be mostly singlehanding anyway I will be able to do what I want to do with the Tiki 26. But working on another Wharram design was certainly interesting, as was doing this as part of a professional boatbuilding team. I certainly look forward to following David's progress and to seeing the finished boat. At the rate it's started, I won't have to wait long.

"No necesito un Tiki 30 - un Tiki 26 es suficiente! Let's see if we can knock this thing down to a reasonable size!" (That's me with the hammer - clowning around with the guys) As usual, I had a great time working with the Boatsmith crew, and building a boat in Spanish is a good way to learn new words in a second language.

Monday, February 04, 2008

Ash for the Tillers

Today was a fine day for early February in Mississippi. A strong southerly breeze brought warm air from the Gulf, getting the temperature up to almost 80F. I took advantage of the sunshine and moved out in the open, where I could set up my table saw and thickness planer to process some rough ash I bought last week to make the laminated tillers. The tillers are another of those small projects that I can start in the garage shop when I'm away from the main building shed. I hope to get them glued up soon, but first I have to go back to south Florida for a few days to work with my friend, David Halladay, of Boatsmith. This time it won't be on a teak pergola or some other extravagance for a Palm Beach mansion, but instead on a much more reasonable project: a Tiki 30 catamaran that he has decided to build on spec. I can't wait to get involved, and I've been invited to help with the hull assembly on Wednesday. I'll be there three days, and it's just as well, since weather like today this time of year is fleeting here in Mississippi. According to the forecast, I'll be leaving just ahead of another strong cold front that will bring more rain.

I'll report back here in a few days on my impression of the Tiki 30 project, but more than ever I remain convinced that in choosing the Tiki 26 I have picked the right boat for my needs. If you want to learn more about David's Tiki 30, check out his blog that I just set up for him here:

Pro-Built Tiki 30

Sunday, February 03, 2008

Tight Spaces

Finally I had a good warm day and the time to work on the boat. The only downside to the weather was the occasional light rain that made it necessary to move all my newly epoxy coated parts into the shed to keep them from getting wet before they cured. Space is getting tight now on rainy days, with two hulls side by side and little available bench space to lay out parts for coating and such. Normally, I set up some temporary benches outside the shed on saw horses. But when it rains everything has to go in.

Despite this, I got all the bunk flats for the starboard hull coated on both sides, as well as the access hatches that are cut out of them. The next step will be to glue on the stringers under the openings for the access covers, then the bunks will be ready to install. While these were curing, I worked on the floor panel fillets beneath the starboard bunks, and these areas are nearly done, needing only one more sealing coat of epoxy.

You can see the how crowded it's getting in these photos, with epoxy coated bunk parts spread out all over both hulls to cure, forcing me to squeeze past them to get to the area where I'm working.

The other "shop" in my girlfriend's garage is a bit full as well, with Tiki 26 beams and a 12-foot Backwoods Drifter under construction. Here you can see I've finished the epoxy fillets on all the crossbeam interiors, and finished the epoxy coating of the webs and floors. The next step on these beams is to make the front fairings and get them closed in.