designing a fast rowboat

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

  1. NoEyeDeer
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    NoEyeDeer Senior Member

    Just thinking about this a bit more. The BioRow calculator for sliding seat boats takes a lot of factors into account, one of which is the height of the person in the boat. This makes sense since the lengths of the relevant body parts, (torso, arms ,etc) are related to the person's height, and a setup that is ideal for a very tall person is not going to be right for a short person.

    The fixed seat calculators are far more basic, and do not take the person's height into account. This is an obvious oversight. If you want to know how to set up a fixed seat boat for a particular person it would make sense to start with their height as the main factor, then tie all other measurements to the position of the footrest.
     
  2. NoEyeDeer
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    NoEyeDeer Senior Member

    While I'm on a roll I might as well throw another idea out there.

    So a fixed seat boat with a beam between rowlock pins of about 4 feet/1.2 metres is really too narrow to use a full length sliding seat to best advantage. This got me thinking that it might (not sure) still be an advantage to use a sliding seat but with a shorter slide. IOW, rather than the standard slide distance of about 50 cm/20" cut it down to about 30cm/12" for rowing with oars of about 230 cm/7' 6".

    If used with less torso swing than fixed seat this would allow oar angles at catch and finish that match what the sculls use, while not requiring outriggers or very long oars. The short slide should still be usable in standard street cloths too, so you wouldn't have to wrap yourself in lycra or whatever to go for a spin. Jeans should be fine.

    The seat and slides would not have to be tied to the footrest as one bulky unit. Australian surfboats have had sliding seats for years now, and the seat/slide combo is a separate unit that drops into the boat, with the footrest being another unit fixed to the boat. This would make changing things around to carry a passenger more convenient, since you'd be dealing with two small units instead of one big one. It's also potentially lighter overall.
     
  3. Tallman
    Joined: Jun 2011
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    Tallman Junior Member

    Blackburn Challenge 2016

    This thread has been pretty quiet so I thought I'd update it a bit.
    The BC was rowed last Saturday in fairly calm conditions for the first 75%, with some wind, seas and wakes for the last 25% or so. We went against the tide for the first 2-3 miles until we got out of the tidal "river" and then against it again for the last 1.5 miles before the finish.

    Ben Booth triumphed in the Touring Single with a beautiful new design of his and had a blistering sub 3 hr time. He was followed well back by several FISA coastal singles.

    I planned to use a double version of Ben's Westport Racing Skiff (WRS2) but didn't get the rigging worked out in time. It's very fast but I belatedly discovered that I need to lower the seat and rigger as, currently, in rough water, it's really tender.

    So with no time to correct that, I got out the old Firefly2, which is super stable but slower. In a patchwork fashion it made it's way across the country from L.A. to Gloucester. My brother, who doesn't scull much but does do ultra marathons, was my partner.

    The two guys who have won the Touring Double the last two years have a very nice and very fast carbon Eurodiffusions double. We figured we had a shot at second place as the other boat, a Tango 17 Whitehall, is pretty slow and a fourth entry didn't show up at the starting line.

    Racing and touring doubles went off together and former Olympian Tom Bohrer and his partner, in a Maas double, quickly vanished. After a few minutes I was surprised to find us dogging the stern of the Eurodiffusions boat through the buoy and boat clogged river. We intentionally went out hard to try and stay with them, and maybe unsettle them, but this I thought was too good to be true. We passed them after about 2 miles and realized that they were very fit but less experienced in terms of technique. They made a few runs at us but we gradually pulled away. Towards the end the fast double kayaks blew by us and the last 1.5 miles in the supposedly sheltered harbor was crazy choppy and slow due to wind, tide and wakes. We finished in 3 hrs 56 seconds which I'm a bit surprised at given the not perfect conditions. Our stroke rate was too low -- 22-23 -- due to too heavy a load on the oars and just tweaking that (we didn't have time for enough test rows) could have got us under 3 hrs, and still kept us below the planned HR cap of 145 for the body of the race. The event is a hoot and wonderfully put on; anyone who can make it there should give it a try.

    As for the Firefly2, it's a station wagon versus the sports coupe that is the WRS2. But despite a total weight of about 120lbs with rowing rigs, the thing moved fast and just barreled over everything it encountered while staying stable and allowing us to crank hard. We only had to use the venturi bailer about 4 times.

    Here are some pics --
    https://drive.google.com/open?id=0BwzVuKKSDAt-NlplcmMzTGJXR0E
    Apologies for the pic dump -- too lazy to attach individuals
     
  4. keith66
    Joined: Sep 2007
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    keith66 Senior Member

    Meanwhile on this side of the pond we had the Round Canvey Island race, run by Benfleet yacht club. 21 starters of all sorts. Due to the narrow width of the creek we send the slowest boats away first with the others at 2 minute intervals, Its an interesting race with first leg a long hard 3 1/2 mile pull against tide & sea breeze, then out into the Thames estuary & up the outside of Canvey to holehaven & back into the creeks. I was using my latest boat a stretched Cosine wherry, she is 16ft 8" long & carries a 75 sq ft lugsail for downwind sailing. Rowing with my son Nick who is 20. We were the smallest boat so first away, quite surprised to be only caught by the gigs just before the first turning mark.
    As we were the token Sail & Oar class entry up went the lugsail & the next 7 miles flew by as she surfed downwind. Last leg it was back on the oars.
    Fastest Gig was Whitby Fishermens RC 6 oared 32ft Gig which did it in 2 hrs 3 m &20s rapidly followed by three surf skis
    We took 3 hrs 5 m.
    Im well pleased with the boat she is light & handles beautifully.
     
  5. nordvindcrew
    Joined: Sep 2006
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    nordvindcrew Senior Member

    Finally got 3500 l.f. of western red cedar milled up. Bead and coves run, the bad spots all cut out, ends scarfed and glued into boat length strips. Setting up the strong-back today and will start to take off the sections from my 16' skin on frame boat. No race boat this time, just something that will row well and get me back on the water. Hope to have the hull glued up and ready for fiberglass clot before the weather turns cold. Wish me luck on this, I've never done bead and
    cove before
     
  6. nordvindcrew
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    nordvindcrew Senior Member

    progress

    The strong back istogether, leveled and squared. The boat is on it and leveled up. The bridge is on the strongback and I'm ready to start taking the station lines
     
  7. nordvindcrew
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    nordvindcrew Senior Member

    Molds now complete. set up soon then, finally building in a week or two. Don't know if I'll have a complete boat before cold weather ( building outside) but will be back on the water by spring. This is a strip buiolt version of the skin-on- frame boat I raced 5 years ago.
     
  8. NoEyeDeer
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    NoEyeDeer Senior Member

    Post some pics once you get going with this. From what I hear, bead and cove shouldn't present any problems. Even basic rectangular strips are pretty easy to deal with.

    It's interesting that you're not doing a race boat this time. I've hardly used my 19 footer since I built it, due to the rigmarole involved in getting it to the water via my truck. I'm seriously thinking I should do a little pocket rocket that could just be thrown into the tray without requiring cradles and other complications. Something around 12 1/2 feet could be built at about 40 pounds ready to rumble, and with the right design would be easily quick enough for basic solo recreational use.
     
  9. nordvindcrew
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    nordvindcrew Senior Member

    No race boat? Well, I said that, but the skin-on-frame boat I'm using to get my molds was my race boat for 6 years so I know it rows pretty good. The problem is me. One cancer operation and three heart procedures have pretty well decimated me. I just wantto get back on thewater and row. It will require a trailer, but that's Ok. Going from a multi-chine S.O.F boat to a round bilge has forced some changes into the boat: A little wider waterline,a finer entry and the need to lengthen the boat at the bow and stern by a couple of inches to get the strips to lay in fair. I'm not trying to get an exact duplicate of the original, just a similar boat that might look good and row well.
     
  10. NoEyeDeer
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    NoEyeDeer Senior Member

    There's nothing wrong with "looks good and rows well". :)
     
  11. nordvindcrew
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    nordvindcrew Senior Member

    back bone is almost complete: laminated the stern knee this A.M will do final assembly tomorrow and do any fairing necessary on the molds. Might be ready to start the strips by the weekend. With the changes made, the boat is 5" longer and will be 2" deeper with more sheer. i've got no idea of finished weight but am hoping for well under 100 Lbs. If that's not enough, there are the birds-mouth hollow shaft oars to complete. No rest fr the weary.
     
  12. nordvindcrew
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    nordvindcrew Senior Member

    progress

    first 11 strips are on after much messing with the molds. The shape looks good with only a bit of a problem at the stern ( tucks in a bit quickly ). the bow is tucking in nicely with the sweet hollow bow I wanted. Have to wait overnight for the glue to dry then another 6 or 8 strips tomorrow. I'm getting close to the turn of the bilge where the curvature gets more extreme and think it will be quite a bit slower. Total cost, so far, about $55.00 due to salvaging a lot of red cedar and milling my own strips, re-using wood I had around my house and just plain sweat equity. I have a question. Is it absolutely necessary to use epoxy to glass the hull? I did a test panel, saturated the wood with thinned polyester resin, let it harden then set cloth in fresh resin. It seems to be good and strong. Any thoughts?
     
  13. NoEyeDeer
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    NoEyeDeer Senior Member

    Use epoxy. Seriously.
     
  14. KJL38
    Joined: Jun 2008
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    KJL38 Junior Member

    Are you clamping or stapling the strips? I started off clamping then switched to staples which was much faster and more accurate.

    My Adrondack Guideboat in 8mm paulownia and 6oz glass is about 55lb. I wasn't very neat with the epoxy and it has heavy stems.
     

  15. NoEyeDeer
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    NoEyeDeer Senior Member

    Hey KJL, what's your opinion on those scantlings? Do you think 6 mm paluownia and 4 oz glass would be feasible?
     
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