Aaron Hines Design Portfolio

Kayak Seat

2009:  The kayak development continues with a seat for the prototype.  The seat borrows an idea from traditional kayaks that utilized ribs for their structure.  The initial thought process formed around creating a one-piece seat that would have been fastened to the inside of the gunwales, providing thigh and sacral support while keeping one off the skin and keelson.  After some consideration, I realized that the one-piece seat idea not only required a non-trivial amount of effort and materials to create, but it would be impossible to install with the skin and coaming in place.

At some point, the idea to turn the one-piece seat into ribs came about, and it did not take long to determine that it would be relatively easy to prototype, install, and test, giving similar support qualities to the one-piece seat.  Because of the hull shape in the cockpit area, only one rib shape was required to span the open area between the plywood stations.

The ribs are laminated from thin slices of pine, and glued with Titebond III – all materials I happened to have on hand, and not necessarily the best materials to use for such a project, but sufficient for a proof of concept.  The ribs are fastened to the inside faces of the gunwales with a single screw per side.  No greater effort was required to mount them securely in place.

The rib seat works wonderfully, and even without any kind of foam padding feels much better than no seat at all.  There is sufficient thigh support, and no longer does the forward plywood station put undue pressure on the back of the thighs causing discomfort and eventually reduced blood flow.  Coupled with a sheet of closed-cell foam and a back rest/sacral support, the rib seat should be a comfortable and viable alternative to other seat styles used in skin-on-frame kayaks.  Expect a final report after more extensive testing has been conducted.

X1 Kayak Prototype

The X1 kayak has been prototyped, although its only been paddled a few times.  First impressions are that it meets most of the design goals:

• more speed – it is certainly much faster than my other kayaks
• less stability – while less than my other kayaks, it is not difficult to handle and is not as challenging as I had hoped it might be
• easy to build – the frame went together in only a few days
• “modern” appearance – without deck lines it looks very minimalist, but it needs on-deck storage as nothing is accessible below deck while underway

The frame was built from found/salvaged materials: the scantlings are redwood, resawn from a 5′ long 6×6 beam, scarfed together to make up the lengths needed; the plywood frames are a mixture of various types and thicknesses; the deck stringers are left-over redwood; stems are scrap cedar; the coaming was made from scrap red oak.  The only materials purchased were epoxy (for scarfing and assembling the frame), skin cloth, and skin coating.  The original skin – varnished linen – wrinkled up after coating and was easily damaged due to the coating remaining very soft.  The current skin is polyester coated with polyurethane.  It also wrinkled up, but not as badly; the polyurethane coating has proven to be much more durable.

It is not perfect, however – it could use a seat or some kind of floor, deck lines, and a better skin without wrinkles – but those are pretty minor problems to have.  Otherwise, it really needs more time on the water to determine if the hull needs any revisions.  Stay tuned!

Additional photos available here

The next kayak…

Circa 2008:  Since July 2007 I’ve been hard at work trying to flesh out the next skin on frame kayak to build.  I took it upon myself to read up a bit on kayak design and naval architecture in general so that I would have a better understanding of what I’m doing.  The design brief has changed a bit as I have learned more about kayak design, but the constant themes have been that the kayak had to be capable of more speed (i.e. longer) and a bit more challenging (i.e. less stable, i.e. narrower) than the retrieval.  I also wanted the kayak to be easy to build, with as few aesthetic features as possible (i.e. “modern”).  I played around with many different designs, from 11′ to 16′ in length, and 18″ to 23″ in width, and took some long and ultimately dead-end tangents in form and shape. 

I finally settled on 15’7″ x 21″ as a compromise between speed potential, wetted surface area, and stability.  On paper, its speed potential (measured as resistance) is average for a kayak its size.  While longer kayaks do have more speed potential if you have the power and fitness to make use of it, that potential comes at the price of greater surface area (more resistance at lower speeds) and increasing difficulty with transportation and storage.  The width is not particularly narrow for an historical skin kayak, but its moderately narrow for a modern, commercial sea kayak, while being on the short end of the length spectrum for both.  If calculations are correct, it will have a suprising high amount of stability because of the boxy hull cross section.  While I initially thought that going for very low “skill building” stability would be a good thing, designing for higher stability came with only a small handicap in speed while (hopefully) giving a kayak that inspires more confidence and allows one to relax without constant attention to prevent capsize (i.e. more fun, less work, since that’s what a hobby is all about!)

The final thing worth mentioning is that I intend to build this kayak from as many found/scrounged/salvaged materials as possible.  Wood, fabric, and lashing material is pretty easily found, but skin coating and glue is probably best bought “fresh” so that there is less likelyhood of failure. 

Below:  A few of the various design dead-ends.

The ‘retrieval’ kayak

Circa 2006-2007: I had always wanted to build some kind of small boat, and in doing research on boats, plans, etc. I came across a wonderful resource for skin on frame kayaks that directed me towards some of the smaller documented kayaks of the arctic.  To put it lightly, I ‘fell in love’ with the ‘skin boat’ technology and abandoned all other construction methods to help get myself out on the water as quickly, and for as little cash, as possible.  After seeing the construction techniques advocated by the most prolific designer of home built kayaks, I took off adapting the lines of an early 20th century North Alaska “retrieval” kayak design to more modern construction methods.  Using Rhinoceros 3D, I built the frame digitally, making some modifications for ease of construction along the way, until I felt I had exactly what I was after.  I had intended to built it from one sheet of 7/8″ plywood, with all parts CNC-cut, but the longitudinal components weren’t up to the task and were later replaced with solid wood during construction.  The CNC-cut cross sections, bow, and setern assemblies were used.

The frame construction took about a solid month of evenings and weekends to complete.  There is minimal glue used, with most parts being doweled and/or lashed with artificial sinew (waxed nylon fiber).  I assembled the frame outside during the winter, and needing to use very little glue allowed me to make progress dispite temperatures being much too low for glue cure on most occasions.  The plywood is yellow pine, 7/8″ thick, and the solid wood is mostly pine, but western red cedar and spruce were also used in a few places.   The frame weighs in at 29 lbs, which is a little heavy for a skin boat its size, but this is due to the heavy plywood and pine used.

Adding the skin took another month of long nights.  The skin is stretched over the frame and sewed together along the deck, which is both easier than one might imagine but also quite time consuming.  The actual fabric is a light weight polyester – much lighter than most skin boats use – but for protected inland lakes, and my low budget, it seemed adequate.  The skin was sewn on with dental floss.  The coaming is attached by sewing as well, but it is held in place with heavier nylon cord and artificial sinew.  Once the skin is sewn on, it must be coated to make it waterproof.  I chose to use Rustoleum enamel, since it is both cheap and available in many colors (I still chose black, however!).  I painted on coats of enamel until I had used almost 2 quarts and was satisfied with the smoothness of the hull.  The skin and paint added 10 lbs to the total weight, bringing the total weight to 39 lbs.  Again, a bit on the heavy side for a skin boat its size, although its lighter than commercially-produced plastic kayaks of a similar size.

So was it successful?  Yes!  It floats, and paddles nicely.  Its not particularly fast, but no 10′ kayak is fast compared to the more typical sea kayaks that range from 16′ to well over 19′.  I made enough changes to make it my own design really, its longer than the documented original by 10″, and the gunwales are oriented at a different angle, not to mention the construction methods.  The deck is lower, and the cockpit is larger/longer and of a modern shape.  I made many changes and design decisions for the wrong reasons, even though it turned out well overall.  Dispite the short comings, I paddled it often during 2007, even on Lake Norman in 2′ chop.  This little black duckling has changed my life, however; it was the most enjopyable and rewarding of the many projects I’ve undertaken, and I cannot wait to build another.