: Zimmerly/Morris use lashings & pegs while Putz uses screws and glue for
: fastening. Zimmerly's article indicates that the lashings allow more
: flexibility. Do they offer comparable strength? Possibly the willow and
: oak thing?

I'm not sure strength is the issue. Putz plans on building a stiff boat. Like a plastic or woodstrip kayak, the Walrus is rigid. This comes from the trestling he uses to make the sides very stiff. I find a lot of similarity between the walrus and the Klepper in that regard. If you look at the sides of the Klepper they consist of a ladder-like arrangement of two long pieces of wood joined by a panel fo plywood, which stiffens them, and turns them into something like a lightweight I-beam. Putz's design uses pieces of the same material that is used for the long strips, and they are placed at an angle to provide the bracing.

Since the Putz boat is NOT designed to flex a lot, the connections are made securely, with screws and epoxy glue. Likewise, the Klepper's sides are very well braced and quite rigid. The Klepper design has 9 decades of experience and it's pretty hard to argue with their success in those years, so I have a hard time finding fault with a stiffened frame. On the other hand, the flexible, lashed frame has a very long record of use, too. Either of these would be stiffer than my inflatable boat

: Putz uses external keel and side rub strips. Looks like a nice idea, but
: something seems scary about screwing through your skin after you went to
: all the trouble to get it watertight. Does this make the boat leak, or
: does it seal pretty well with the screw pressure?

Screw pressure should do the job, but applying the strip right on top of a fresh coat of paint can help, too. The paint forms a very effective gasket, and so does the compressed area of the coated skin which is pinched between the inner keelson and the outer keel.

: Putz skins the bottom and top separately, while the others are skinned with
: one big piece. Any particular reason?

Others do two piece canvas skin, too. The advantage of attaching to the gunwale or sheer strip is one reason. Another is that you can get the deck to drape independently of how the hull skin fits. Traditional craft were sewn as stone- age craftsmen did not have copper tacks or staple guns. The aerolite (sp?) boats have skins that are held by a hot-glue web, and the plastic skinned boats are highfrequency welded. What ever works for you. Many frames can be skinned in more than one manner.

: The Zimmerly boat from a recent Sea Kayaker is flat bottomed. How does this
: type of boat paddle compared to a v bottom hull? More initial stability,
: slower?

The frame may suggest a flat bottom, but don't believe that the actual bottom will be flat. It won't. Water pressure forces the fabric to bend over the frame, creating channels, and where the frame pushes out the fabric, it serves as a long, shallow, keel. This effect has some positive influence on tracking. YOu may see a bit more with a Vee shape hull. The Vee shape, again, would be a bit stiffer. A boat which bends under a load is going to have a variable amount of rocker, as the center of gravity will sink lower and the ends will float higher. This makes turning easier. Conceiveably you should get pretty good tracking and still have easy turning.

:I'm thinking of shrinking this boat down to 18 feet which gives it
: a 21 inch beam. Should still float, huh, or will I be paddling upside down
: the whole time?

How much do you weigh? You can just shorten the thing and keep the width if you want. your displacement will change with changes in length or width. If you change both, your displacement changes even more. This also affects how low the boat is in the water. If you are light, go with a short boat. If you are heavy go with a long boat. If you are heavy and must have a short boat that fits in the garage, or can be shipped, them make the width suitable for your weight.

You'ld need a computer-based design program to get the exact info, but I think your wetted area and drag will be about the same with a narrow boat that sinks lower as it will be with a wider boat, which will float higher. The lower boat may feel more stable when it is loaded, as it will have a lower center of gravity.

: Putz makes his cockpit part of the frame, while the Zimmerly boat cockpit is
: almost free-floating on the canvas with only a few frame attachment
: points. Is that still pretty secure?

I haven't looked at how Zimmerly attaches the coaming, but it had better be strong enough to support your weight during entry and exit.

: The Putz and Morris designs I saw use stem pieces, whereas the Zimmerly boat
: brings the keel and stringers all the way to the stem. Any advantages one
: way or the other? I'm guessing the latter is a bit simpler. I first
: thought the stem pieces would be sturdier, but the attachment points with
: the keelson and stringers could be a weak point.

Unless you plan to make a habit out of ramming floating logs or icebergs, I doubt you'll find either of these methods to be weak. By making the stem pieces from several smaller pieces of wood which are built-up to the desired shape you can get good strength, and have the wood grain aligned in a strong direction, with out adding a lot of weight. You also don't need to steam-bend pieces.
If yo are going to steam-bent ribs, though, steam bending the stems is just a matter of two more bends out of 50 to 100. Not much extra work there.

: Does anyone make these boats with bulkheads and hatches? Seems like you'd
: have to tie ropes to everything you stuffed into the bow or stern to get
: it out again.

If you laced the deck cloth together like you'ld lace a shoe, rather than sew it, then you could just loosen the laces to get access to the bow or stern areas. You could also remove the skin completely, and even take apart the frame for shipment or storage.

: Maybe I'm overthinking this. My guess is all of these boats work! I'm
: probably going to adapt from both styles.

They are not very expensive, nor very time consuming to build. Try BOTH systems!

Enjoy your building.

PGJ