Outside of the Office > Hitia 17
Construction of my Hitia 17 Catamaran
The Hitia 17 is a design is from James Wharram, an eccentric British designer with some 50 years of catamaran building behind him. His book 'Two girls, two catamarans' describes his voyage in the early 50's accross the Atlantic in his home made 22ft catamaran, 'Tangaroa'. It looked god-ugly with flat bottoms, and boxy cabins, but it did the job despite the scepticism of the yachting community at the time. The best part was how he managed to convince two cute German girls to join him for the ride on a voyage which ended up taking a couple years... now, this is my kind of guy!
Wharram has since designed dozens of catamarans to be developed out of plywood and easy to construct for the home builder. I decided to take on one of his smaller designs, the Hitia 17 in late 2001. The plans cost around US$250 and are worth every penny. Detailed drawings and descriptions are laid out on some 13 large sheets, and cover everything from the hull construction to sewing hatch covers, and the sail plan. Wharram does not include the 'lines' of the boat, or a traditional construction plan but provides dimensions and diagrams for what to cut, and 3D illustrations of how pieces go together.
I've been very lucky to have some training in building wooeden boats from Robert Darr at the Arques School of Traditional Boatbuilding in Sausalito. During the time I studied as an apprentice there, I learned to build boats in the traditional plank on frame method. Plywood stitch and glue construction was, however, new to me.
Construction started with the purchase of almost $700 of plywood and lumber. The hull sides are made from very thin (4mm - 5/32") plywood. This is not much thicker than 'doorskin' used in many pre-fab homes. 1/2" ply is used for many of the sturdier parts including the stem and stern of the boat, and for the rudder. Lumber is used for stringers, cross-beams, mast and many of the attachments to the boat.
Plywood comes in a number of grades and qualities for different types of purpose - 'Marine grade' ply is fabricated to be without knots or voids (holes within the ply) to protect from rot and seepage of water. There is still further grading on the quality of the outside veneers... eg. A/B would mean that one face is excellent, and the other face is good. And there are some standards such as BS 1088 which ensure that the ply is well constructed with durable glue.
Strangely enough ply made to marine grade does not need to be of a durable tree species. - All wood is prone to rot in a damp enviroment, but some woods are well protected by internal pesticides. I was only able to find Finnish Birch and Okoume (an African wood) in the dimensions I needed. - Neither are well known for their rot resistance... still the theory is that once it is encased with epoxy, the rot resistant properties are not so important.
Wharram provides a complete list of the dimensioned lumber that is needed to build the boat. - I assume that this could be ordered from a lumber yard and they could cut the wood to size. However, as I had access to a table saw, and large band saw at the school, I choose to buy three long pieces of Douglas Fir, which I would later resaw down to the sizes I needed. The longest piece was 18ft long and held enough wood to cover the mast, sprit, and stringers that ran the length of the boat. The other pieces provided the remainder of the stringer stock, and wood for the crossbeams. Doug Fir is expensive. - $330 for the three pieces.
Much of the initial work was in laying out, cutting, and then glueing together the pieces which would make the hullsides. At this early stage there is also a lot of time spent coating the plywood with epoxy, and then sanding, and then re-applying more epoxy in order to seal the plywood from water. The hullsides are then stiched to a thin keel (1/2"x 3/4") keel with copper wire, and then opened out by sliding in the bulkheads. Visually similar to a pita bread being stuffed with meat. The six bulkheads are then stiched in to create a boat-like structure, which although wobbly looks like a boat. - This seemed easy enough. It took almost 70 hours!
The wire stitches are temporary, but the real strength in this boat comes from epoxy fillets that are then applied. Epoxy is a two part glue which hardens when the resin and hardener are mixed together. When it has fully set, it is stronger than the wood it bonds. However, epoxy is fickle stuff, and if the enviroment is too cold or too moist will not set properly. The timing of the chemical reaction which hardens the glue also varies also on the volume of glue mixed. A mixed cup of epoxy can easily 'go-off' with 10 minutes. An alarming experience when you suddenly find yourself holding a blistering hot cup of smoking goop belching noxious fumes. On the other hand, when spread as a thin coating, the chain reaction take may take several hours, which is plenty of time for dust,dirt and insects to get included too!
My initial experiences with epoxy were often frustrating and stressful. Not only is there time pressure to complete the job, but you must protect yourself from the glue with gloves and by avoiding the fumes. In the initial stages I got the glue everywhere... panels would stick together accidentally, or the wind would come up and blow dirt all over. But with time I learnt to clean up excess glue, cut down on the mess, judge quantities and prepare jobs so that time pressure was minimized.
Still, epoxying was never fun. Most unpleasant was the filleting of the hulls where fillers would be added to the glue to bulk it up to enable it to fill the corners. At first my fillets were too liquid, resulting in ugly looking fillets as the glue sagged. When I did get the hang of it, I would work in dismay at the quantity of glue I was using. Epoxy is expensive... a gallon of resin and hardener work out to $80. - All told, I went through almost 6 gallons of resin. Perhaps Wharram has stock in West System!
Occasionally Bob, my mentor, would come out to check on progress. There was always a faint sense of amusement as he would watch me struggling with the glue. "It all takes time," he would comment, and in this lay a fundamental truth. Whatever method of building boats, there is an unescapable fact that whatever construction method, they all take time to reach the end goal. For my next project, I will ask first, which is more pleasant... the fastening copper rivets into freshly planed cedar, or bonding rainforest plywood with toxic epoxy?
With the bulkheads in, work progressed to fitting decks, and the cockpits. More plywood to cut out, and more filleting to be done. The keel fillet inside the boat is also covered with a layer of fiberglass, and then the whole outside layer of the boat is covered.
Fiberglassing was for me the most dreaded part in the construction. However, with the filleting experience behind me it wasn't as hard as I feared. Fibercloss comes as a shiny woven cloth. It might even look nice as part of a ballgown! It adds huge strength to the boat when laid over the hull, and 'wet-out' with epoxy. After the glue sets up, it becomes almost invisible. Wharram provides plenty of good advice on fiberglassing with the plans, and his methods work well.
Then follows many hours painting, and then significant woodwork on the crossbeams, locating blocks, spars, tillers etc. With the help of my girlfriend Stephanie, we made the sails ourselves out of blue tarp in 25 hours and for only $40!!!
It may sound like a simple project, but all the little things add up and consume huge amounts of time. In total the boat consumed well over $3000 in materials [Cost Breakdown], and 540hours of time [Time Breakdown]
All told, building a boat yourself is not a cheap way to own a boat. - At the time I started building this boat, bulletin boards in the area were advertising 20yr old Hobie Cats for $600. - A friend of mine came into posession of a 14ft dinghy for a couple hundred dollars. Second hand Hitia 17's are selling on Scott Brown's Brokerage from $2000. Even a competetive new dinghy will retail for under $5000 which is significantly less than this boat when you place a value to the time spent building your own boat.
But, of course that would be missing the point. - Fundamentally there are few things that are as rewarding as creating an object of beauty, fun, and use from your own two hands. Owning a flash boat is nice, but the experience building it was worth far more than the parts cost and the time spent.