designing a fast rowboat

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

  1. nordvindcrew
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    nordvindcrew Senior Member

    I'll look at Bolgers' plan. Ideas are always good to contemplate. We ( I row with my brother as a double crew )are seriously considering a fabric decking to cover all but our rowing stations. That cross wind factor is real, and creates a ton of resistance, anything to minimize it will help. The boat is partly molded. Next weekend we'll mold up the 8' bow section again then set the two bow section and the mid-ship bottom panel on a strongback. With a lot of battens we will fair out the shapes and create a basket to support 1/8' melamine covered panels. with some bondo and elbow grease a new section of mold should emerge to allow us to bond the whole thing together into a 20' double ender. It won't be an ideal boat, but then, none are. it will be (we hope ) good enough to beat the one crew that consistantly beats us. Last race, over 4N.M.we came second by 26 seconds. Close but no cigar! As you see, we don't need too much to get out in front. Racing this Saturday. 6 miles up stream on a tidal river, we're class winners for 8 years but the competition is getting better and we're getting older ( 57,63 ) wish us luck!
     
  2. nordvindcrew
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    nordvindcrew Senior Member

    fast rowboat update

    molded third major panel of the new boat last weekend. pieces now have to be joined and faired in. Process will probably take several weekends.
    Looks like we will have it ready well in advance of our November race. How do I attach photos to this message? I've got a couple of pictures of the current state of construction I'd like to post
     
  3. nordvindcrew
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    nordvindcrew Senior Member

    current state of build. Shows two half sections together. will be stretched 4' in middle for 20' plus finished overall length. third photo shows a 20 'skin on frame rowing boat as a 1/4 scale model
     

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  4. messabout
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    messabout Senior Member

    Nord;
    Lookin' real good so far. It appears to be a little deeper than I would have imagined but you have said that rough water is a reality. Every thing is a compromise with boats.

    The four foot mid section will make it ride higher still. I reckon you have already agonized over the question of substantial additional wetted surface vs WL length advantage. The boat under construction is classy looking but the model looks like the ultimate weapon to me.

    You guys must be some hellatious athletes at ages 57 & 63. All us old guys will be rooting for you. Keep us informed.

    Gene
     
  5. nordvindcrew
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    nordvindcrew Senior Member

    fast rowboat update

    We intend to get it in the water to see where she really floats. if there is too much freeboard, we can trim the sheer to reduce windage. Wetted surface is one of those necessary evils; to get enough waterline length we have to suffer more wetted surface. We can get up to 21' L.O.A with our current pieces, and will probably go that way. the overhangs are quite long and we give up almost 1' at each end. As to being athletes, we're construction workers and do no time in the gym. Our wins come to the fact that we are more wiling to hurt ourselves than others. Being of Norweigan heritage helps too,we hate being beaten. A healthy shot of grog before each race also is a good bracer. Open water rowing in New England is an older persons sport although there are a lot of kids rowing gigs and a few younger guys in singles aqnd doubles. A nasty running chop of 2'-3' is common in most of our races. In one race we came second by 21 seconds to a low freeboard boat that was within a heartbeat of going down due to the amout of water that had come over the side. I'll post more pictures as the boat progresses. Thanks for your interest
     
  6. charmc
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    charmc Senior Member

    Nordvincrew,

    You began with a good open water rowing design, the Jersey skiff. The Jersey skiff was built mainly for rough seas, so not necessarily the fastest. Your current design sounds like you've done a nice job improving on the original. looking forward to receiving the trials reports and photos.

    Good luck!
     
  7. nordvindcrew
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    nordvindcrew Senior Member

    fast rowboat update

    Charmc, this boat in the photos is more based on a Scandanavian Faering. Our second boat is a Jersey Skiff built of plywood with batten seam construction. It's a good boat and carries her hull speed well. When we designed her, we put too much of a forefoot in and she tends to yaw badly in a steep following sea. At some point, we're going to rework the stem, put some rocker in the forward section of the bottom and reduce the forefoot. At 260 pounds she is heavy but rows very well. We finished the Blackburn Challange, a 21 mile race around Rockport and Gloucester Massachusetts, in under 4 hours and were beat out of second place by 26 seconds when 2 power boats cut across our bow and forced us to alter course. Last race, July 28th, in the original faering design at 16' 9" we finished first, 6.5 miles, in a time of 1 hr. 6min, 21 sec. time is deceptive because we were in a tidal river and had the tide behind us for half the way up stream.
     
  8. charmc
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    charmc Senior Member

    Nordvincrew,

    Making the forefoot shallower and adding some rocker will make it more like the original design; sometimes the old designs are pretty good.

    You and your brother bracket my age nicely. I'll be rooting for you; nothing wrong with setting the bar for the young guys. Strength of character (often defined as the ability to endure pain over time) oft counts as much as strength of body.

    That being said ... 21 miles in under 4 hours in open water? You guys are animals! Go for it! :)
     
  9. nordvindcrew
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    nordvindcrew Senior Member

    Open water Rowing

    to find out what we're doing up here in New England, Google Blackburn Challange and check ouy the race results. We havent done that one since 2002, but it's in our plans for next July.
     
  10. nordvindcrew
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    nordvindcrew Senior Member

    race times

    in the 2001 Blackburn we were third with a time of 3hrs 48 min 29 sec, 29 seconds behind second. Second place was Keith robinson in a stretche Gloucester Gull, first place was the Carter Brothers from New Hampshire rowing a 22' long Pistaqua Wherry which is a dory with one added chine down low. They finished in 3hrs 15 min and change. They're real animals and the crew we've got our sights on. we're creeping up on them every race in the shorter boat. The longer boat with less rocker in the bottom might get us up there with them.
     
  11. melong
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    melong Junior Member

    You sound like tough old buggers. Good luck with the race.
    About that stretched Gull you were up against: it wasn't planing.
    What's the bottom length on it? I've only seen the original Gull and they're quite short on the waterline. I imagine the stretched one would have a waterline of 16 to 16.5 feet. At that length two blokes can push it past hull speed and being fine sterned it will start to squat. This happens to any boat in that speed range.
    It'd be faster if longer, or would squat less with a broader stern.
    Your new boat looks good but personally I'd have gone narrower on the waterline. I reckon you could knock 8" off and still have adequate stability.
    I had a recreational boat I built myself with a 23" waterline beam and that was fine, but I was sitting quite a bit lower than you will be. Mind you I did stand up and pole the thing around in flat, shallow water. Waterline length was 18 feet.

    My idea, if you ever want to build another boat, would be to go at least 20 feet waterline length and around 30" waterline beam. Lotsa flare in the topsides to get your rowlock spread. Like one of the other guys said, match your prismatic to your average speed over the course.
     
  12. melong
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    melong Junior Member

    Damn. Now I wanna build another fast rowboat.:D

    Hey I noticed in another thread you were asking about moving the maximum beam aft of midships. Yes that will cut wave drag and pitching but don't push it too far. Apart from balance issues you also need to keep your beam at the forward rowing station of course. Mind you you can do that by playing with the flare.
     
  13. nordvindcrew
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    nordvindcrew Senior Member

    waterline beam

    Melong, we won't be able to test float the boat until about September. It looks like about 30" waterline beam may be somewhere near it. Waterine length should be 18'6". we push our rowing stations as far forward as reasonably possible to help maintain directional control so we need to keep bouyancy forward as well.
     
  14. melong
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    melong Junior Member

    Should be ok. Earlier you were looking at 38" BWL so I thought that's what you still had. Make the next version 2' longer I reckon.
     

  15. melong
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    melong Junior Member

    Ok, if you're into rough water racing check these guys out. The boats are built to race from the beach, out through the shore break, around a course and back to the beach. They are no longer used for lifesaving as they have been superseded by outboard powered inflatables, which cause much less damage to the person being rescued.:D
    http://www.geocities.com/rowboy78/
    http://www.harvpix.com/photos.asp?path=Ocean Thunder Final&scount=2

    Wonderful boats though. The shore break can be over twelve feet, depending on conditions, and yes they still race when it's like that. The basic shape is good but not having a sweep for directional stability means you'd need a skeg. Note the interior is designed for minimal floodable volume with a narrow self-draining well (via pumps over the side). The narrow well minimises free surface effect as well as volume.
     
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