: Is there a benefit to using a "lashed" type of kayak frame such as
: Morris suggests verses a more rigid frame that Putz describes? Will the
: rigid Putz type kayak be more susceptible to catastrophic failure (the
: frame breaking in half for example)? This is in reference to quiet water
: paddling, no open ocean and no wild rivers.

You may be phrasing this question in a way which will give you no useful information. So instead of answering what you asked, let me try to give you some counsel on the matters you address.

Compared to a solid fiberglass kayak, nearly ALL skin on frame kayaks will be very flexible.

The trestling or crossbracing used in the walrus is there to control how flexible those long, skinny stringers are. While there are many nice things to be said about very flexible kayaks, I think the extreme would be an underinflated inflatable kayak. Personally, I have two inflatable boats, (not kayak shaped) and they are slow, difficult to paddle and difficult to keep on track. They are a lot more fun with a small trolling motor! You need SOME stiffness.

How good are your lashings? If you draw them tightly you limit the flexibility of the rib and stringer, just as a screwed or glued joint would limit the flexibilty of the construction at each joint. If you encounter a sufficiently large impact then something is going to fail. It matters little whether this is a broken lashing, a cracked rib or stringer, a severed glue line, or a screw ripped out. Each of these problems can be solved, they just have different solutions. Well, that's only partly true -- you could probably solve ALL these problems with a roll of duct tape -- but otherwise you just pack your repair kit with the appropriate spare parts.

Fortunately, neither type of frame is subject to sudden catastrophic failure unless it is grossly overloaded, subjected to great shock, or made with materials which are much weaker than specified. The Walrus design was copied by Skeene from similar native designs, and then Putz ahd the plans redrawn by a certified naval architect, whose autograph you can see on the illustrations of the plans in his book. Hopefully this should reassure you that there was indeed a good deal of planning in these plans.

When a naval architect works on a plan they need to have some constraints. In particular, they have to know how much weight the boat will be carrying on average, and on up to a maximum load. They use amthematics to determine the size of the boat based on the weight of the paddler, and convert those measurements into inches or fractional parts of a meter. The Walrus plans are drawn up based on a paddler of a given size. You can manipulate the design by increasing the length, or decreasing it, and "fudge" a bit to tweek the design to be a better fit for you. Mike Hanks has done this with the Walruses he has built. He went back to Skeene's measurements which are in the Skeene article in the back of Putz's book, (and they are a bit different than what Putz has) and used those as a base for the modifications on one of his Walruses.

When building from anthropometric details you are trying to do roughly the same thing. You want a boat big enough to hold you, but not so big that it is awkward. I believe that the anthropometric methods, using fists, arm spans, and finger lengths, which have historically worked for the Inuit are not accurate with paddlers who are much bigger than the average Inuit. I may weigh two to three times what an average Inuit weighs, but I'm sure that my fingers, and fists are barely larger than theirs -- and certainly not two to three times bigger. For me, working with anthropometric measurements would probably produce a boat which would be too small for my needs, so I'd end up fudging a bit here and there -- making the length greater, and also the width.

Pick the design you like and build it. You will enjoy it, and later on you may decide to try building another boat using different techniques and plans. then you can compare the two crafts and draw your own conclusions.

There are also several other methods of building skin on frame kayaks. The third major method uses frames cut from plywood, or assembled from short boards, which remain inside the boat. Clark Craft (www.clarkcraft.com) has reasonably priced plans for about a dozen boats built this way.

Good luck with your project.

Hope this helps.

PGJ