Monday, February 26, 2007
Tuesday, February 20, 2007
I didn't do any work on the boat over the weekend or Monday, but I was back at it again today,working on the preparations to the sternposts and rudders as described in my last post. The epoxy fills in the drilled out slots I made in the sternposts last week turned out great. This mixture of wood flour and silica has cured rock-hard and will provide a solid, waterproof section for the small holes that will be drilled for the lashing line. I sanded these smooth today to remove excess epoxy buildup, but they will have to have one more application of thickened epoxy for the final fairing before they are ready to be glassed over and then drilled. I went ahead today and drilled out the matching slots in the rudders, and started the filling process in those this afternoon. When filling a large cavity such as these with epoxy, you can't just pour it all in in one batch, as large amounts of mixed epoxy concentrated this way will get very hot in the reaction process and could literally boil over, leaving air pockets and voids in the filling. To make these fills, I first coat the inside surfaces of the cut-outs with clear, unthickened epoxy, then fill a small amount and allow that to partially cure before mixing more epoxy to fill some more. To completely fill these holes has taken three separate applications with curing time in between.
With the rudder slots cut and the first batch of epoxy filling in them, I turned my attention back to the sternposts and began making hardwood inserts to glue into the notches I cut last week in the trailing edges. These notches, as described in my previous post are simply clearance notches with a rounded over surface to allow the lashing lines to bear against them without chafe. Rather than just round over the cut edge of the plywood, I wanted to seal and protect the plywood by cutting the notches a fraction deeper and then laminating in these inserts. I made the inserts of solid mahogany, first by cutting a piece of stock the exact thickness of the plywood, then using a roundover bit in the router to radius the edges, then slicing off a thin strip with the table saw, and cutting these strips to the exact length to fit each notch.
The hardwood inserts are shown here, adjacent to the notches they will be glued into
Here the inserts are glued into place. After the epoxy cures, they will be further shaped with a nice rounded edge on each side, then the whole area will be glassed over before the lashing holes are drilled. After the boat is built, the fiberglass sheathing on the hull will also cover all exposed areas of the sternposts and skegs with an additional layer of protection.
Friday, February 16, 2007
First a line is drawn 18mm back from the edge of the skeg, directly behind each lashing notch described in the previous post. I then used a 1/2" Forstner bit in my drill press to drill a hole at dead center in the line, at each end of the notched area.
The slots are filled with a thickened epoxy mixture that is about the consistancy of ketchup, so that it will self-level and completely fill the area. I first taped pieces of poly plastic to the other side of the slot to prevent the epoxy from running out. These large slots cannot be filled in one step, as the epoxy would get too hot if it were all poured in at once. This could cause it to expand and leave air pockets inside, so I'm doing the fill pours in stages, probably 3 or 4 separate steps, allowing at least partial curing in between. When these are finished, I'll cut the rudder slots and do the same, then sand all these surfaces, mark the exact lashing holes, and drill them out on the drill press. I know I'll thank myself for all this extra work when it comes time to hang the rudders on the finished hulls. And with a good quality Dacron line for the lashings, the rudder attachments won't need attention for years to come.
The finished notches on the adjoining rudder and skeg assembly.
This is one of those tasks that is much easier done before the boat is built, but this efficiency is not suggested in the plans. I wanted to completely finish the lashing assembly while the skegs and rudders could be laid on a flat work bench and parts could be cut and drilled with the table saw and drill press.
I know firsthand from experience with my Hitia 17 and my Tiki 21 that this rudder lashing method works great. It is much smoother than conventional rudder hardware, and much cheaper too. My Tiki 21 was fitted with stainless steel gundgeons and pintles when I bought it, and I converted it back to the Wharram method of lashing. Accurately drilling the holes for this lashing is difficult after the boat is built, as it is hard to drill a perpendicular hole by hand, especially as close together as these holes must be. Being able to place the mating edges of the skeg and rudder together on a flat surface makes it much easier to accurately mark these holes. I plan to drill them on the drill press, but first, there are many steps to take before I get to that point. For long term longevity in a wooden boat, it is essential to prevent moisture ingress into the core of the plywood. Any holes passing through the plywood are pathways for water to enter, and the only reliable way to keep it out is to first overdrill any such holes, then fill the larger holes with epoxy, and then drill the finished holes through this hardened epoxy so that the walls of the holes are solid epoxy and no wood edges are exposed. I'm taking it a step further with the rudder lashing holes and will explain this in the next post.
Thursday, February 15, 2007
Julio checking out the progress on the epoxy table
Tuesday, February 13, 2007
Some other steps I plan to complete before assembly include such details as pre-drilling the skegs for the rudder lashings while I can more accurately do this on my bench top drill press. I will first drill oversized holes and fill these with a silica epoxy compound, then drill the correct sized holes through the cured epoxy so that no wood will be exposed to possible water ingress through these holes. These kinds of steps will delay the beginning of building the hull, which I'm anxious to start, but in the long run it will make such jobs easier than working in an awkward, vertical position. By the time all these jobs are complete and all the epoxy coats are on all these parts and the new roof is done on my shed, the weather will be steadily getting better here in Mississippi and the days will be getting longer. I'm only three weeks into the project, and have logged as of today, 44 hours of labor. I expect to be well into building the hulls by March or April.
Saturday, February 10, 2007
This method is much faster than applying epoxy with a disposable brush, as I often do, or even with a foam roller. Basically, you just pour the mixed epoxy around on the hull panel in a figure-8 pattern, or swirls or whatever, estimating approximately how much you need to wet out the entire surface. Then you pull it around all over the dry areas with the rubber window squeegee, (I used a small, handheld model bought in the grocery section of Wal-Mart). After spreading it out as much as possible, you then go back over it with a foam roller, smoothing the coating and further wetting out any dry areas to ensure a consistant, even coating. It's fast, doesn't waste epoxy, and makes it easy to apply the thin coats needed as sealer coats on all the parts before assembly. Thanks Thomas!
Okoume plywood can be really beautiful when coated with epoxy, as can be seen in the above photos where it is gleaming in the sunlight. I used it before to build two Pygmy kayaks, the Coho and the Arctic Tern designs. These kayaks were finished bright inside and out. I still have the Arctic Tern, my favorite of the two, and it still looks great, turning heads wherever I go with it. I plan to enjoy the natural beauty of the wood grain in the interior of the Tiki 26, finishing it clear with epoxy and then a U.V. inhibiting marine varnish. When building a wooden boat that you intend to finish bright inside, care must be taken to sand away or erase such marks as layout and lofting lines, numbers, labels, notes and other things you may have written on the bare wood parts. On the hull panels, bulkhead station lines will be needed to correctly position the bulkheads, but these lines will be hidden by the bulkheads themselves and then the fillets. Another consideration for finishing the interior bright is the filler material you use in the epoxy to make the fillets. I prefer to use a mixture of wood flour and silica for all my fillet making, as it is strong, looks good in a natural finished boat, and is relatively cheap. For this project I'm using pine flour, which makes a very nice, light tan colored fillet that blends well with the color of Okoume.
These hull panels were still a bit tacky at sundown today, and the temperature will probably fall to near freezing, but with more sunshine expected tomorrow, they should be completely cured by mid-day. I won't try to sand and second coat them right away. Epoxy sands much better after it's had a few days to cure, and besides, there are other parts I can work on, like the upper hull side panels.
Yesterday was rainy and cold, limiting the amount of epoxy work I could do, but I'm slowly prepping the bulkheads (6 for each hull) by making and installing the bunk bearers that the bunks will be fastened to, and getting the first coats of epoxy on them. The bulkheads shown above are the number 4 bulkheads for each hull. These are the bulkheads at the forward end of the cabins, just aft of where the mast beam crosses the deck.
I'm making a slight modification in the cabin accomodation area by raising the bunk levels three inches (75 mm). Because the hull sides flare outward, a slight height increase of the bunk levels also creates bunks that are slightly wider. This is a change I had long contemplated as I thought about building the Tiki 26, mainly because I wanted a little more elbow room inside as I am 6' 2" tall, and having been inside a few standard Tiki 26 cabins, this seemed like a fairly easy and logical modification. Of course, the cabin tops will have to be raised a corresponding amount to have the same amount of headroom over the bunks, and I've worked out two different approaches to this that will work without greatly altering the outward appearance of the boat. This amount of height increase will not be enough to increase windage in any significant way, but will give me just a little more breathing room down below for those times when I might be confined in one of the cabins by weather conditions.
You cannot think of interior accomodations on a small Wharram in the same way you think of more conventional sailboat interiors. You don't live in the cabins while cruising, but rather on the whole boat and most of the time on deck. I certainly plan to incorporate some sort of deck tent into my cruising set up when the boat is complete, possibly along the lines of the dodger/tent combination used on the new Wharram Tiki 8-meter design. The main requirements regarding the cabins as I see it for offshore and bad weather sailing are: dedicated dry bunks that are ready for use without major rearranging of stuff or set-up, a galley set up that allows cooking and brewing coffee, etc. while underway, a place for spreading out charts and other navigational tasks that is protected from weather and spray, and a comfortable place to sit inside each of the cabins with the hatch closed. These can all be achieved in the Tiki 26 as designed, and that's what makes this boat ideal as the micro-ocean cruiser that Wharram calls it.
Thursday, February 08, 2007
The garage is filling up with bulkheads, stems, skegs, rudders and misc. parts. I've been using the table saw to cut the bunk and floor bearers that will be glued to the bulkheads. A table saw is practically essential for quickly making these kinds of parts. This one has a router table set up in one of the extension tables, making it two stationary tools in one.
Tuesday, February 06, 2007
Tonight I worked in the garage for awhile, using the table saw to rip up some Doug Fir stock into pieces to make the bunk and floor bearers which must be glued onto the bulkheads before assembly. I'm cutting these to length and labeling them as to which bulkhead they go on, then using the router to radius the bottom, exposed corner so there won't be any sharp edges inside the storage lockers down below the bunks. Making and installing all these bearers will be time consuming. After they are all in place I'll begin coating the bulkheads. This weekend I plan to be back at my main building site where the hull panels are stored. If weather permits, I'll spread those around on saw horses and whatever else I can find and start getting the epoxy coats on them.
Monday, February 05, 2007
The stems are a very important visual aspect of the finished boat - that is at least the part that rises above the deck level. I didn't want to use the exact shape given in the plans, as the "handles" that are cut into the stem and stern posts are pretty useless on a hull that weighs over 400 pounds. These were useful on my Hitia 17, and to some extent on the Tiki 21, but they have been a source of problems as well, particularly as my 17 and 21 were built of Doug Fir marine ply. It's hard to glass around these handle openings, so on both of my other boats I had problems with checking of the surfaces. With the Okoume I'm using now this should be less of a problem, but I didn't want the handles anyway and decided to make these pieces solid, as on the Tik1 30, and with a bit of an upswept flare, as on the Tiki 38.
I'm working on a paying job all this week during the best hours of the day, but thanks to being able to do some of this epoxy work inside I'm still able to make progress.
Like the stems and skegs, the upper one-third or so of the rudders are doubled by adding a 6mm ply laminate on each side. While working on other parts I glued all of these up, completing the last one this morning. It will be a long time before I need rudders, but the parts were already cut when I cut up the single sheet of 18mm ply, so these can be worked on at times when I'm in between stages of epoxy curing or whatever on other projects. This is one way to maximize available time and get ahead on all those little parts that have to be completed before the boat is complete. When I built my Hitia 17 I started with just the hulls and was dismayed at the amount of time it took to build crossbeams, rudders, tillers, mast, etc., before I could go sailing. This time around I'd like all those things to come together at about the right time, so when it's time to start painting, I can paint everything, then assemble, fit-out, rig and prepare to launch.
Sunday, February 04, 2007
Another power tool I use extensively in my woodworking is a small belt sander. It's incredibly handy for trimming parts for a precise fit in joiner work and in this case it's great for trimming cut plywood parts exactly to the line. When cutting the parts I cut to within a blade's width outside the marked lines and then use the belt sander to quickly and accurately finish the edges to the line. For this kind of trimming I use 50-grit belts for fast removal of material. This method does require care, however, as a belt sander is a powerful tool that can quickly ruin a piece of work if you let it slip or get out of control. That's why I prefer the smallest size belt sander, one that uses 3 x 18" belts. These are lightweight enough for one-hand use and for getting into tight spots a larger belt sander could not reach. I also frequently use it to shape small parts by holding or clamping it upside down to a work bench.
In the photo above, I'm using the belt sander to get an exact match on the bulkheads for each hull. First, I cut out and trimmed the one that was lofted from the plans, then used it to mark its counterpart in the second hull, and after cutting the second one, I clamped the two together along the centerlines and used belt sander to trim the second one to the exact size of the first. This only takes a few minutes for each bulkhead, and the result is six bulkheads for each hull, perfectly matched.
I finished cutting out the bulkheads for both hulls yesterday. Here I'm using the jigsaw to cut the stringer notches in the bulkhead sides. Just as I've done with the hull sides, I carefully lofted and cut all the bulkheads for one hull and then used those for patterns to cut the parts for the second hull. This saves a lot of time if you have the space to store all the parts until you get around to using them. When I start building the hull in my open shed, I'll have room to build both of them side by side, but I may not start the second one until the first is completed to bunk or sheer level.
These are the two saws I'm using the most to cut out the Tiki 26 parts from the plywood sheets: a jigsaw and a small 5 1/2" circular saw. These are 18-volt battery powered Ryobi saws, which are inexpensive but surprisingly powerful and efficient. I use a lot of power tools in my work on other people's boats and in cabinet making and other residential carpentry. I've come to realize most hand-held power tools are going to need replacing in a few years or even less, so I don't often buy the most expensive brands, but there are definately some cheap consumer grade brands I stay away from. I've found most Ryobi tools are a good buy for very little money and are far better than the competition in their price range. I've been using the circular saw in the photo above for more than two years now, any time the convenience of a cordless saw outweighs the need for the extra power and heft of my Makita 7 1/4" saw. I've only had the jigsaw about 6 months, but I've found it incredibly handy. The key to any saw is the blade anyway. Before starting this project I stocked up on new blades for each: Marathon for the circular saw and Bosche for the jigsaw.
In the Wharram plans a jigsaw is recommended for cutting out all the parts. This is much too slow and inaccurate, and I only use the jigsaw in tight curves and for cutting such notches as those found in the bulkhead sides. A small circular saw with the blade set to minimum depth will cut most of the curves in these boat parts, such as the hullsides, bulkhead sides, etc. It's much faster and more accurate as well. Of course there are a lot of other tools that are handy to have as well and speed things up if you have them. I can't imagine being without a table saw, for example. I used mine to quickly rip the 1-foot wide plywood panels for the hull topsides. And it will be essential for making the stringers, bearers, braces, mast and beam parts and other solid wood parts.
Saturday, February 03, 2007
It was still too cold to do epoxy work out in the garage this morning, so in order to keep things moving I brought the stems and skegs inside. I wanted to get started glueing on the 6mm doublers that go on each side, so I put them on some card tables covered with plastic sheeting to keep from glueing them to the work surface and used temporary drywall screws to assemble the parts. I use a lot of these drywall screws in my boatbuilding, as they are easy to shoot in with a power driver, requiring no pilot hole, and they are just as easy to remove once the epoxy cures by reversing the driver. The holes they leave are not an issue as these surfaces will be epoxy coated and glassed (on the outside parts) and the holes are easily filled with thickened epoxy. It's faster than clamping and is especially useful for glueing parts that have to be kept flat or straight until the glue sets, as you can simply use long enough screws to go right into the work bench - providing of course you don't forget the plastic sheeting between the part and the work surface, and that you don't do this when using your girlfriend's card tables! In this case I used short, 3/4" screws that were just long enough to hold the parts to the main 18mm plywood stems and skegs. These will be cured overnight, then I can flip them over tomorrow and glue the remaining doublers on the other side. This operation only took about a half hour to set up and complete. I spent several more hours out in the garage and finished cutting out all the bulkheads. I have more photos from that job that I will post in the morning.