penetrating standing waves

I understand the relative shape and width of the dory bottom influences/determines the resulting shape of the hull. Generally, what does widening the bottom in a dory do to its flare and sheer? If the design matters, consider the gunning dory.

There was an article on early river boats in a recent Wooden Boat. Don't have the edition information at hand but can get it. Let me know.

Gary

 

Depends on what the designer/builder does. Flare can be kept the same, increased or decreased. Similar for the shape of the sheer.

 

Thanks David. I think I read that in reference to planked boats and the natural bend planks assume when bent around the flaring hull.

Gary

 

No, any type of construction. I'm assuming all parts of the boat could be changed.

Are you asking what happens if you take the bottom out and put in a wider bottom while keeping the sides the same or something similar? If so why would someone do that?

 

Inflatable white water craft have large reserve bouyancy to get the job done.

Stiff kayaks with skirts have less and behave like submarines and get the job done even better.

Dino

 

David,

I was only suggesting to widen the bottom from 20" to 30-36" at midship but keep the frames and stems unchanged as much as possible. I read somewhere that widening the bottom in a dory would reduce flair. Again, I think it was in reference to planked hulls. I was curious if others had had any experience with that.

Thanks for trying to help me understand.

Gary

 

David,

Forgot to let you know the article on Norm Nevills and his early boats in the GC is in WB 219 - March/April 2011.

 

Surf boats are for competition, not recreation, and used on ocean surf, not river rapids. But breaking surf looks an awful lot like a backcurling standing wave, which is what causes the most trouble on a river (besides rocks and trees), and I think what works for one, probably works for the other. I've been looking over photos of surf boats and their bows look an awful lot like what is on my canoes. That is, a rounded transition from the bottom to the stem, not a lot of overhang to the stem, and some flare (flam). It is interesting to note that it would be impossible to make a bow shaped like this with a single chine boat. I've said it many times before and I'll say it once again, drift boats and river dories developed from the Banks dory because that was a known design that was easy to design and build, not because there was any inherent superiority in the design, and it was known by the fisherman on the Banks that round sided dories performed better. Let's try something besides the inferior single chine, flat bottom design.

 

You can say it as many times as you wish, but drift boats and river dories did not develop from the bank dory. They developed from river skiffs and bateaus. See Roger Fletcher's book for a detailed study of the evolution of drift boats and river dories. Ease of design and construction may have been a factor in the evolution of the design.

Where did you get that from? As far as I'm aware all the dories carried by schooners and used on the banks had straight sides. Some inshore fisherman and other users used and prefered dories with rounded sides.

Go for it. Design, build a boat and try it. Perhaps you will come up with a better design.

 

If you keep the angles of the frames unchanged and just widen the bottom the flare stays the same but the angle of the stems becomes less. Experiment with models made from some thick paper or thin cardboard and tape.

 

Thanks - enjoy the conversation.

Gary

 

Beyond the Hundredth Meridian: John Wesley Powell and the Second Opening of the West. [Paperback] by Wallace Stegner 1954

There isn't a lot about the boats in the book but the description of them is basically a dory.

 

Photos of Powell's boats from his second expedition are available at: http://www.nps.gov/grca/photosmultimedia/THE-POWELL-EXPEDITION.htm

Illustrations from Powell's book Canyons of the Colorado showing the boats are available at:
http://www.powellmuseum.org/RunningaRapid.html
http://www.powellmuseum.org/GreenRiver.html

The boats are round bottom with transoms, similar to Whitehalls but decked. Not related to dories.

 

From a website about the history of Grand Canyon river running:

(underlining added)

 

From Canyons of the Colorado, John Wesley Powell (Book may be downloaded at http://www.gutenberg.org/ebooks/8082):

Illustration from the book showing the boats: