penetrating standing waves

Discussion in 'Boat Design' started by river runner, Oct 23, 2011.

  1. garren
    Joined: Mar 2009
    Posts: 31
    Likes: 1, Points: 8, Legacy Rep: 11
    Location: Billings, Montana

    garren Junior Member

    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
     
  2. DCockey
    Joined: Oct 2009
    Posts: 5,199
    Likes: 598, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    Depends on what the designer/builder does. Flare can be kept the same, increased or decreased. Similar for the shape of the sheer.
     
  3. garren
    Joined: Mar 2009
    Posts: 31
    Likes: 1, Points: 8, Legacy Rep: 11
    Location: Billings, Montana

    garren Junior Member

    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
     
  4. DCockey
    Joined: Oct 2009
    Posts: 5,199
    Likes: 598, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    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?
     
  5. dinoa
    Joined: Oct 2007
    Posts: 240
    Likes: 26, Points: 28, Legacy Rep: 97
    Location: florida

    dinoa Senior Member

    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
     
  6. garren
    Joined: Mar 2009
    Posts: 31
    Likes: 1, Points: 8, Legacy Rep: 11
    Location: Billings, Montana

    garren Junior Member

    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
     
  7. garren
    Joined: Mar 2009
    Posts: 31
    Likes: 1, Points: 8, Legacy Rep: 11
    Location: Billings, Montana

    garren Junior Member

    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.
     
  8. river runner
    Joined: Jul 2011
    Posts: 172
    Likes: 6, Points: 0, Legacy Rep: 91
    Location: Colorado

    river runner baker

    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.
     
  9. DCockey
    Joined: Oct 2009
    Posts: 5,199
    Likes: 598, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    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.
     
  10. DCockey
    Joined: Oct 2009
    Posts: 5,199
    Likes: 598, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    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.
     
  11. garren
    Joined: Mar 2009
    Posts: 31
    Likes: 1, Points: 8, Legacy Rep: 11
    Location: Billings, Montana

    garren Junior Member

    Thanks - enjoy the conversation.

    Gary
     
  12. Ike
    Joined: Apr 2006
    Posts: 2,613
    Likes: 418, Points: 83, Legacy Rep: 1669
    Location: Washington

    Ike Senior Member

    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.
     
  13. DCockey
    Joined: Oct 2009
    Posts: 5,199
    Likes: 598, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    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.
     
  14. DCockey
    Joined: Oct 2009
    Posts: 5,199
    Likes: 598, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

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

    (underlining added)
     

  15. DCockey
    Joined: Oct 2009
    Posts: 5,199
    Likes: 598, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    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:
    [​IMG]
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.