designing a fast rowboat

Discussion in 'Boat Design' started by nordvindcrew, Oct 13, 2006.

  1. nordvindcrew
    Joined: Sep 2006
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    nordvindcrew Senior Member

    surge

    boat weight is also a big factor. Our 19' Jersey skiff weighs 260 pounds then add another 300 for me,my brother and gear. Get that moving and the speed is absolutly linear, no surge at all. the lighter the boat, the greater the surge, or so it sems to me; at least from my experience.
     
  2. nordvindcrew
    Joined: Sep 2006
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    nordvindcrew Senior Member

    skin on frame

    New boat is nearing completion. Longitudinal stringers and deck beams are all that's left before the skin goes on. The skin will be 15oz canvas,shrunk into place and varnished for waterproofing with a finish coat of marine one step epoxy or something similar. It will help me to understand the differances betwen a heavy and light boat. I think it will weigh about 70 pounds or maybe a bit more with all the final things that need to be in place but are forgotten for the moment. We will be racing on August 2nd. 6.2 miles on the North River. It is a medium sized race and the rowing competition isn't too great. We'll row for time unless some other boats show up that we don't usually see. Still not in great rowing shape but geting back slowly. Lots of bad weather and the aches and pains of being 64 have reduced my efforts. I hope the new skin on frame single will encourage me to get out more often and give it hell. Only way I know to improve.
     
  3. DrKungPao
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    DrKungPao Junior Member

    pictures?
     
  4. nordvindcrew
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    nordvindcrew Senior Member

    pictures

    will try to post pictures but my computer sees attatchments as a problem and won't let me up load them. not much to see, just a bunch of strips of wood in the shape of a boat. won't look like too much till the skin is on ( and maybe not then)
     
  5. DrKungPao
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    DrKungPao Junior Member

    everythings interesting to a first time boat builder like me :). Good luck on the rest of the project!
     
  6. nordvindcrew
    Joined: Sep 2006
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    nordvindcrew Senior Member

    race day

    plans have changed. We'll be racing at the Scituate Harbor Heritage Day Race on Saturday Aug. 2nd. about 3 miles; out of the harbor, around a bell bouy and back in. Short enough to row hard and not too long to wipe us out. The competition may be better there also. The new boat is looking more and more like a boat. 5 of the 8 stringers are in and the shape is really getting defined. I have one rib, 2nd fron the transom that is a bit out of shape causing an area of unfairness. I'll release the rib from the gunnell, apply some towels soaked in boiling water and the problem will go away. Doing the project over, I would leave all the ribs clamped to the gunnells and fasten them once the stringers were on after adjusting them for a fair shape. Moving a rib up or down by 1/4" makes huge differences in the shape
     
  7. DickT
    Joined: Apr 2008
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    DickT Junior Member

    I think that's why the vikings planked first and put the ribs in later. Glad to hear you're getting some race time on the water. They rescheduled a local 3mile race to Sept here because of T-storms .
     
  8. nordvindcrew
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    nordvindcrew Senior Member

    race

    Last year, I rowed the race single and got massacred. To add insult to injury, The Tucker, a coxed four, rammed me. I was on the way out and they had rounded the mark and were on the way in. The kid coxing must have been asleep because they hit me a glancing blow on my starboard side just ahead of my oarlock. Not a word of apology from the ******** except from one guy in the crew I know.
     
  9. kmorin
    Joined: Apr 2005
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    Location: Alaska

    kmorin Senior Member

    Rowing Seats

    nordvindcrew,
    I sure have been rooting for the crew of the Nordvin and her sisters, for quite a while, and this is certainly one of the most interesting topics on this web site.

    I'm posting these pictures of a row boat I built, not a racer, just a rowing dory, but the boat is not what the post is about; I want to show you the seats.

    A few pages back there was some discussion of (fixed) rowing seating and I've decided my old stern can't sit on hard surfaces much longer. These nylon webbing seats are just a truck tie-down strap, or two, wrapped around some aluminum pipe welded to the two thwart (pipes) so that the rower's rear is suspended in a 'lawn chair' type of seat.

    I think they are comfortable and believe they could be made of wood thwarts holding the pipe/tube and get the same results?

    These seats are used by the rowing guides in the Rogue and MacKinzie River rowing 'dories' both in Oregon and here in Alaska. I've done my version of their seats but the idea is from these guide boats where a man is sitting for many hours and handling a boat full of fishermen in the currents of a river.

    These seats are light and will dry out pretty quick and the ratchet strap can be tightened or loosed so the 'fit' of the seat will hold anyone.

    Please keep up the great reports of your rowing adventures and boat building, it has been very enjoyable reading. I only build in metal, so I'm not too informed about building in other materials, but the same lessons learned apply to all row boats' and I especially enjoyed your remarks about row station proportions and layout.

    thanks for your contributions here,

    Cheers,
    kmorin
     

    Attached Files:

  10. nordvindcrew
    Joined: Sep 2006
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    nordvindcrew Senior Member

    seats

    hey Kmorin, Great pictures, I can see how those seats would be comfortable. Could they be able to be made with a wood frame instead of aluminum? The race went well: 2nd overall. The only boat that beat us was a sliding seat coxed four. Our time was 30:27. not ver fast for 2.5 miles but there was a four knot cross current all the way out and back. I'm not sure how to figure the offset but I'll bet it added almost a half mile to the actual distance rowed. You work in aluminum, so I have a question for you: if you are familar with the San Francisco Bay Pelican sailboat, could it be easily done in aluminum. I want to build the 16' model to trail behind my Toyota Rav 4, so light weight is important.
     
  11. kmorin
    Joined: Apr 2005
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    Location: Alaska

    kmorin Senior Member

    Wood Framed Seats

    nordvincrew,

    I'm sure a couple of closet rods of hardwood would do the trick replacing the aluminum pipe as the seat side rails. Supporting the seats would be simple by raising the ends of the wooden dowels up enough over the area of the seat webbing to allow for sag, and to loosen the webbing to allow a deeper seat.

    One thing that is somewhat non-intuitive about welded aluminum boats is that the smaller they are the harder they are to build; one-off. I'm overgeneralizing, making too broad a statement, but only to make the point that larger boats with heavier scantlings are more forgiving of fit and weld contraction.

    The dory in the pictures is about 17' LOA and weights about 175-180 dry, seats, oar locks and oars add nearly 50lb so she's about 200lb. without crew. Its made of 0.100" and all welded. It was a major pain in the stern to build compared to the heavier (larger) boats because of the thin material's weld contraction response. I'd say a 16'er would be best built of 0.125" and that would be more forgiving a material than the 0.100 or 0.090" materials in the dory. One reason I choose the thinner material was the double bottom, I didn't want to end up with two pieces of 1/8" plate for the bottom and deck. But is was a major pain to do and looking back I'm sure I'd repeat that choice. So in planning your Pelican in metal I'd say weight planning needed to go hand in glove with the materials choices to make sure you don't try to build too thin and then weld that material. Scaling aluminum welding down past a certain ratio is a bit of work.

    Any hull shape that can be made in sheet goods will build in metal as long as you're willing to put proportional welds to the metal.

    Glad you placed well in the last race, we're always interested in seeing your pictures of the boat the gear and the race setting, so don't hesitate to post them?

    Cheers,
    kmorin
     
  12. kmorin
    Joined: Apr 2005
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    Location: Alaska

    kmorin Senior Member

    Pelican in metal

    nordvindcrew,
    I didn't realize the boat (Pelican) was a pram, that means the topside and bottom panel shapes are usually fairly soft turns. This shape would build in metal- easily.

    I'd round the stern and bow with cones to fill the same space as the pram's flatter panels but other than that it would build in welded metal very simply. Cones can be cold formed for both ends and stiffen the metal greatly and help somewhat with more displacement up higher in the shape.

    Cheers,
    kmorin
     
  13. nordvindcrew
    Joined: Sep 2006
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    nordvindcrew Senior Member

    race pictures

    To see some race pictures, google "team saquish rowing" and enter their site. click on photos. We're on page three top row, second from left, last boat away from camera. Thats the "Nordvind". Third row last on right, i,m on the left, brother dave on right. we did second in that race, beat by a long St. lawrance River skiff that got us at the start and then held their lead. The Nordfjiord at 20' will be an answer to that once we get her new bottom on and seating and oar stations sorted out. Next week, I'll canvas the new single and start waterproofing her. No name yet, but will continue in the "Nord" tradition. Any suggestions? Maybe north bird, north star, north sea? Haven't heard from Clint Chase lately. Sea trials yet, and if so how does she row?
     
  14. Clinton B Chase
    Joined: Mar 2005
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    Location: Saco, ME

    Clinton B Chase Senior Member

    Jeff,

    The update is that the torn cartilage in my right wrist joint is healing and I feel about 95% back to normal. In fact, last night I had a scary dream of launching my boat and it had so little capacity that I alone sank it to the top of the sheerclamp and the stern was nearly underwater, she was like a 12' double paddle canoe with 9' oars. I awoke with a fright and vowed to get working on the boat again. After repairing my bandsaw and an event in Brooklin, I'll be back at it next week and will post an update. I have been able to draw and you can see that work on a dory design at:

    http://www.boatdesign.net/forums/showthread.php?p=220901#post220901

    Cheers,
    Clint
     

  15. nordvindcrew
    Joined: Sep 2006
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    nordvindcrew Senior Member

    get well

    Clinton, sorry to hear about the torn cartilage in your wrist. Hope you are 100% soon and can get Drake sorted out and in the water. let us know how it works out
     
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