new member (would like to build the SOF rowing wherry Ruth)

Discussion in 'Boat Design' started by whosail, Nov 12, 2014.

  1. NoEyeDeer
    Joined: Jun 2010
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    NoEyeDeer Senior Member

    Makes sense to me. Vertical bending is what seems to give problems with SOF boats. The horizontal bends take care of themselves, since they pull against each other on the opposite sides.
  2. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    What happens if you put a straight board on the gunwale when it needs to be curved vertically, is that the board straightens when you release the frames. This hoggs the boat, bends it upward in the center (including the keel). The only thing stopping it from going straight is all the other stringers including the keel which now get bent until it all balances.
  3. Petros
    Joined: Oct 2007
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    Petros Senior Member

    making a pattern should not be necessary, but if you are making out of plane bends (compound bends) in the stringers a stiff strong back will be necessary until it is all assembled. normally on a skin 0n frame kayak or canoe, you adjust the angle of the gunwale flair to get the amount of shear, or up-turn in the gunwale sweep. about 15 degrees from vertical gives a nice upward sweep of the gunwales fore and aft in a kayak sized hull. I have done several dinghys the same way, but used a bit less flair in the gunwale. once you have the gunwale set, the rest of the hull is made with much lighter square (or even round) stringers, so the gunwales are what give the boat the shape and structure. once you set the gunwales to the deck beams (or in the case of a canoe, thwarts), the main shape of the hull is set.

    Than I temp position the keel with blocks and several braces using clamps and bungee cords. That sets the rocker and depth of hull. Than I steam bend and trim to fit several ribs near the center, "eye-balling" the shape. that allows me to temp set bilge stringers with clamps and bungee cords or even lashings. Now I take strips of plastic as a gauge, postition them in each of the motrices in the gunwales to determine the length of each rib. I transfer the length to rib stock and number each one from front to back, for each mortice positions in the gunwale. I cut and steam each one, put them in and clamp in place, adjusting the shape of the hull as I go. this allows you to cut the ribs to each location to maintain the hull shape that you desire. Most other methods requires you to guess the rib length, altering the final shape and depth of the hull, from what you want unless you take them all out and trim and replace them.

    This way I get the hull shape I want, rather than depend on forms, molds or patterns. All I need to know is length, width, and depth of hull I want, plus the amount of rocker, and I build the frame to those dimensions without any tooling. As you add and clamp each peice the frame becomes more rigid and strong, than you can lash it all at once in the correct shape. The gunwales just sit on two saw horses as I build up the hull from the gunwales downward (with the gunwales upside down, you build toward the keel from the gunwales, unlike most "white man" way of making boats).
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  4. Dave Gentry
    Joined: May 2010
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    Location: Charlottesville, Virginia

    Dave Gentry Junior Member

    Hi Dave
    Lots of good tips here . . . but I suggest it will be simplest if you just follow the directions when it comes to getting the gunwales bent (soaking, and thein weighting their centers). Ruth is quite long, and the bends are easy. And, once the inwales are fixed in place, springback has never been an issue with this design.
    Note that there are lots of stiffer species of wood than Western Red Cedar - if you use one of them, then you might consider trying a different method to get the sheer right.

    Good luck!
  5. whosail
    Joined: Nov 2014
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    Location: Henderson,NV

    whosail Junior Member

    building the Ruth

    Well I have found a lumber company in LasVega, big yard and I think I can find what I need. Sent Dave Gentry a note, hope he will answer. Available is red cedar, yellow cedar, marine fir, clear redwood, etc,etc. A question I sent him: is the measurement he list in his guide, for chine, gunwales, etc, all going to be to cut from the 1" X 3" and 1" X 5"?

    And Mr Gentry, I will go with WRC.

    Thanks for the input and info. When I get started I will follow up with build pictures and progress reports. I will not be building the Ruth in a week or two. It will probably be a month or two when I get every thing together.

    Dave, the old guy
    Henderson, NV
  6. whosail
    Joined: Nov 2014
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    whosail Junior Member

    Wood will be in next week. had to special order it. So far 6 pieces of 1 x 6 x 14. Company is going to deliver. Will probably cut to 10ft and scarf. JUst hope I don't screw up. Will have about $260.00 dollars in would and ply. Also purchased a bench type table saw and at Mr. Gentry's suggestion a Bosch jig saw. You know it is Christmas. Gave away all my woodworking tools a few years ago. Regret it now but as time goes by and you live in the desert instead in the SF Bay area and you are an old,old guy that what some people might do. Anyway I have written this note twice now, hope you guys receive it and give me the advise I will surely need. Dave The old guy.
  7. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    You don't need to cut it all to 10 ft. Just cut some to add the extra 4 or 5 feet to the 14"

  8. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

    Good find, PAR. Happy New Year!
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