Friday, September 28, 2012
Here's the second part of my series on the build of a Geodesic Airolite boat, a Classic 14 sailing/rowing dinghy. The last entry detailed the majority of the woodwork; this one shows adding the synthetic materials as well as some odds and ends.
Where we left off last posting: here's a photo of the frame with foils (daggerboard and rudder) installed to show their proportions.
The next step was to install the kevlar. This is a stiff yarn applied on the diagonals to prevent racking when the hull is put under torsional stress.
After the kevlar is attached to the frame, the polyester skin is draped loosely:
A slit is cut in the fabric at the bow and then attached with heat-activated adhesive.
The fabric is attached along the gunwale and transom and tightened by shrinking it with an iron:
Rub rails installed:
Here are some pics of the finished hull:
I made oars following Jim Michalak's plans. These incredibly material-efficient plans allow for a seven foot oar to be made from an eight foot 1x6 with very little waste. The rough shape is first cut:
The two pieces cut off the sides are laminated to the center part to beef up the shaft:
The shape is then formed with a spokeshave:
Heading for a nearby surburban pond/lake/storm catchment basin:
The maiden voyage:
Seems much better balanced with one than with two:
Hopefully I'll have an update in the spring with sailing rig pics.
Monday, July 16, 2012
The Geodesic Airolite line of boats were designed by the late Platt Monfortt, based upon observation of airplane construction methods. The distinguishing features are a very light wooden frame, a heat-shrunk dacron skin and diagonal kevlar roving. These combine to produce an incredibly lightweight and aesthetically pleasing boat what is surprisingly robust. For plans and a list of their boats, see the company's website here.
A few years ago I built a Snowshoe 14 canoe from a Geodesic Airolite kit and it turned out wonderfully. Pics here. I wanted a sailboat that I could cartop and launch single-handedly and the Classic 14 appears to fit the bill. It is modelled on a New York Whitehall boat and the specs list the weight at 54 lb for a 14 foot long boat with a 48.5 inch beam.
The first step is to cut out and mount stations to act as forms for the construction. You can see my airolite canoe hanging from the ceiling.
The longitudinal stringers are ripped from structural lumber and clamped to the stations. The clamps shown are made from slices of ABS pipe.
The notches for the stringers in the transom are cut to fit due to the compound angle. The stringers are left oversize to be cut to length after the epoxy dries. This is much easier than the double-ended canoe which required compound cuts to fit each stringer exactly to length.
The ribs are next installed. These are steamed to help bend them to shape.
The steaming rig I used is just 2" ABS pipe connected to a coffee can with some aluminum foil and heated with a hotplate. Others suggest a more complex setup with insulation, etc, but this worked fine.
I had a failure on the connection between gunwale and transom, so I beefed it up a bit, which required a bit more complicated clamping than usual.
Here's a shot of the boat just after it came off the stations. This is where I broke the transom-gunwale joint as it wasn't strong enough to carry around without the inwales and seats installed. Note the daggerboard slot.
Here's a detail showing the inwales and the construction of the seats which also help support the daggerboard well
Frame faired and sealed. Next step is applying kevlar.
Since this is a sailboat, there are a couple items to make in addition to the hull. Here's a pic of laminating two pieces of cedar to make the boom:
A sailboat also requires two foils: a daggerboard to resist sideways motion and a rudder to control direction. I made mine out of laminated plywood with an elipsical leading edge. This photo shows initial shaping of the leading edge. I did rough shaping with a power plane, followed by hand plane and sandpaper.
Filling some voids after shaping the trailing edge.
I covered the daggerboard with one layer of unidirectional fiberglass. But not before dropping the epoxy-coated board in a pile of shavings.