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Archive for March, 2011

As a builder of small boats using a garage as my shop, my collection has started getting to the point where it takes up a considerable amount of my work space. I reached the point with the completion of Gertie where I could not start the next project in earnest until a more permanent place for Gertie could be found. With the initial shaping of the gunnels for my greenland kayak coming along, the need became more urgent. I finally talked to the landlord, bought a stud finder, and here is the result.

I made two simple cleats out of some scrap wood and screwed some eye bolts into a joist in the ceiling and the large beam across the ceiling of my shop. I used scrap wood spreaders to keep the webbing loops from pressing the gunwales inwards where there are no thwarts to support them. The result may not be the most elegant solution, as the setup currently requires someone to help lift the boat up while the other opperates the lines due to the lack of mechanical advantage in the system and the amount of friction, but it seems functional.

In the future I may add some pulleys so that boats could be lifted or lowered by a single person. At some point I will also move the cleats further apart. I don’t know what I was thinking placing them so close together.

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After a few weeks without much progress, work has resumed on the Coho. The deck has been sanded smooth. The boat looks strangely naked with the deck sanded out, which I suppose it should given that the hatches haven’t been cut out, the coaming hasn’t been installed and there are no deck lines on it.

The deck was flipped over to work in its underside. Reinforcement pieces have been epoxied in just in front of the cockpit, and Joseph also added some more epoxy to the seams around the triangular piece behind the cockpit.

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Progress is being made on the Greenland kayak, though it doesn’t look like a boat yet.

After marking the frame locations I had to puzzle over rib locations. The Morris book states that you should not have ribs in the same location as frames to preserve the strength of the gunwales. The Cunningham book says nothing about that. I decided to use the number of frames the and frame locating methods mentioned in the Cunningham book, and also plan on using his methods for the ribs. Placing the ribs between the back of the cockpit and the footrest was relatively easy, with adjustments of 1/8 to 1/4 inch for some of the ribs within this part of the boat being all that was necessary to have the ribs locations avoid the frame locations. In front and behind this part of the kayak things were less simple. About 2 frames in front of the foot rest and 2 frames behind the backrest the ribs fell right at the frame locations with the 6 inch spacing between ribs. If I adjusted them for that frame, things got complicated for frames further back in the boat and rib spacing became increasingly erratic.

I finally decided to stop worrying about whether the ribs and frames interfere. This decision was influenced by several factors. The first was that the increased depth of the gunwales I am using will likely reduce the weakening influence of any holes drilled since I am not increasing the depth of the mortises. Where ribs did interfere with rib locations were away from the center of the boat, where it seems like less stress will be placed on the gunwales anyway. I am planning on using dowels to locate frames instead of full through tenons, and the dowel holes seem like they will weaken the gunwales less than tenons the full width of the frames. Lastly, the Morris book says at one point that inconsistent rib spacing detracts from the aesthetic quality of the finished boat. For all these reasons I decided to make the frame placement a consistent 6 inches in front of the footrest and behind the frame at the back of the cockpit.

Next, I built a jig to use with my drill press for drilling out the mortises. I wont go into the details of that except that it allows me to have a vertical fence the full height of the gunwale placed at the right location to consistently drill holes in the center of the gunwale. With the basic jig, I drilled out all 50 mortises in less than 40 minutes after setup.

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As I mentioned in my new years post, I wanted to begin building a skin on frame kayak after finishing Gertie, the Six Hour Canoe. Well, I’m starting! I am pretty excited about it. Allow me to introduce this new project.

I will be working from the Robert Morris (available here) and Chris Cunningham (available here) books on the subject. Each seems to have strengths or just details I like more and where I am using the methodology of one over the other I will try to be clear about whose advise I am taking.

Before even beginning the project each text has you begin defining the dimensions of the boat you intent to build. Each text sets the length of the boat at 3 fathoms, with a fathom defined as the distance from fingertip to fingertip with your arms stretched out. For me that would indicate that my boat should be 18 feet, but the books also define the length of the material you buy for the gunwales as 12 to 18 inches shorter than the finished length of the boat. That would indicate the need for stock that was 16’6″ for the gunwales. With the availability of wood in that length in the area, and with the advise of a local expert on the subject, I decided to shorten the boat to 17’6″, which would allow me to get by with 16 foot gunwales. While being cheaper, it will also allow me to walk around it in my garage far more easily.

Next, I had to define the width of the boat. The Morris book sets it as the width of your hips plus the width of your fists, which for me comes out to 22 1/2″. The Cunningham book offers several options including the width of your hips plus 6″ (giving me a width of 21″) as good methods. With the fact that I had shortened the boat, that I want to be able to go on moderate length camping trips with it, and also that I am fairly light for my height, I decided on a width of 22″. It seems like a good compromise.

The next step is to figure out your balance point while seated, so I followed the instructions in the Cunnngham book and created a teeter-totter. I first balanced the board on a piece of 2×3 set on its length. Then I sat down on it and shifted myself slightly forward and back until I found a spot where I was basically balanced with my legs slightly bent. I say basically because there was a range I could sit in, where by lifting my arms different amounts I could get the board to balance. This doesn’t seem to be an exact science. After finding that position I had Emily hold a short box behind me  and got her to mark the location of the frame that will be at the back end of the coaming. I also had her hold the same box against the balls of my feet to get the position of the frame which will act as my footrest. I marked several other positions which will be used to determine the position of frames and ribs. These marks were transfered to a story stick for ease of transfer to the gunwales and latter use.

I bought the wood for the gunwales last week. A local expert on skin on frame kayaks recommended the use of Western Red Cedar instead of the woods recommended in the books. This will be a digression from either of the books I am using, and to make up for the lower strength of WRC, I will be using 3 1/2 inch gunwales instead of the 2 1/2- 3 inch heights recommended by the books. I will stick with the 3/4 inch thickness.

Last night, with the gunwales clamped side by side, I finished laying out the positions of the deck beams. I am however thinking about shifting the beams behind the cockpit slightly back to provide a little extra space for a more substantial back rest than these boats are often built with. There seems to be a lot of decisions to make while starting out. Next step: Get the positions of the ribs laid out. After that the mortising begins.

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