designing a fast rowboat

[charmc]

Hey Jeff,

Sounds like you guys have been getting whipsawed by weather extremes this winter; always lots of fun. Your brother has the right idea: a door on the workshop makes life a lot more bearable. Right up there with hot cider and rum.

Your comment about the competitiveness and narrow range of speed between trophy winners and also rans says they've done a good job with their class definitions. Competition that close keeps everyone motivated, looking for the little things that will add a fraction of a knot. I've been experimenting with the stroke/glide ratio I PM'd you about a while back. Over a longer distance, I've found that adding a few extra seconds of glide time between strokes allows me to sustain long and powerful strokes for a longer time without getting exhausted. Of course, that only helps in calm to light chop conditions. In heavy seas, the wave pattern dictates the rhythm. I've always had trouble keeping any kind of rhythm in heavy seas. Have you or anyone else here found a technique that works consistently?

Regarding carbon fiber blades, it sounds like a great idea. Exercising some care in handling and storing them should prevent any serious damage. I could be wrong, but I don't think rowing would place the sort of extreme stresses that would cause failure from a small scratch. Maybe make up cloth bags or socks to slide over the blades when not in the boat.

OK, that's about all the constructive thought I can wring out for the moment. "Row hard; no excuses".

 

[nordvindcrew]

oar strokes

Charlie, right on with your comments. the pull, snap, then pause works great in calm conditions. In rough water, as you say, match cadnce to wave pattern; the rougher the water, the more the cadence changes. The boat is in under cover and we're going to fit a trial kel to see how it works then fit the final version in time for our first race in early March. An adition al item will be a full length spray rail positioned at the bottom of the sheer strake. Hopefully, it will deflect the spray down and away from the cockpit. Light weight removeable decks are also a serious consideration to reduce cross wind effects. The class definitions are kind of loose, but seem to even out things to equal a good race. yours, Jeff

 

[Clinton B Chase]

Jeff,

A while back you mentioned that my boat may be considered "rigged" and put in a different class due to the Shaw and Tenney outriggers I plan to use. I don't have the outriggers drawn or mocked up but I might be able to install oarlocks on the outside of the gunwales (under the folded out outrigger I am thinking) so for those races where I would be reclassed, I can fold in the outriggers and use regular oarlocks with, unfortunately, shorter oars. Worth looking into you think? Any contacts you have that I can make to ask the 'authorities' about whether I'd be truly put in a different class? (that still seems absurd...I won't have any sliding seat...having the outriggers would be no different than having a wider boat with gunwale mounted locks!) Let me know. I'm still planking the boat so I have time to research.

Cheers,
Clint

 

[nordvindcrew]

rules

Clint, The rule "on oar on gunnel" is there to keep a boat "honest" . As you know, a narrow beam, all other things being equal, produces a faster boat. If long oars are used on outriggers ( think collegiate shell), denying the outriggers forces the use of shorter oars and levels the playing field. One friend, Jon Aborn, rows a boat of his own design known as a Monument river wherry. It is very narrow and he rows with enormously long oars with only a 3" extension on his gunnels. He has never been called on it, and I guess that much can slide by. We have 2" extensions on our rear station to even the spread front to back, and no one calls that either. By the way, Jon looks like one of those water striders you see on ponds, and he is always the man to beat in a race. long oars on a narrow boat can work, but it takes practice to maximize your speed. I don't know how race officials and other racers would look at a boat with both riggers an locks mounted on the gunnels. Try looking up the different race bodies like Blackburn challange and Hull lifesaving museum to get their imput. Can't wait to see your boat!

 

[Clinton B Chase]

Well i may just try to sneek by...the outriggers add 3-4" per side...pretty hard to notice. I certainly won't look like a water strider...well maybe like a Norwegian water strider.

 

[nordvindcrew]

riggers

I guess that I'd try it too. Worst case scenario, rerig with oarlock sockets mounted on the outside of the gunnels for a little les spread. I'm thinking of 42" beam at the gunnnels with 36" or less at the waterline, maybe 16-1/2' LOA, on the skin-on-frame project I'm determined to do this spring. I was looking at fishing kayaks over the weekend and spent a lot of time studying the rudder system. One lever to steer, another to raise and lower the rudder; very interested to try the idea out on a rowing boat.

 

[sailing canoe]

skin on frame rowing boat

Great thread. there is a skin on frame rowing boat on the Shipyard Raid site. Its 19foot 6ins and has done very well in both the raids it has been in. I think it has a slidding seat though.It would be great to find out more about how it was biult. Its hard to imagine any thing lighter.

 

[sailing canoe]

best sea tand feet position in relation to oarlocks

On another subject; Can anyone give some numbers or proportions for the rowing position on a traditional row boat. I currently row a Mass 24, but its all got to change as the gunnel/oarlock ht goes up.

 

[sailing canoe]

post drawings?

Hi Clint; any chance to post drawings of your new boat? sounds interesting. As for ocean sailing canoes are you familier with Yackaboo ? we will have to start a new thread to dicuss it though. Ok I go-- its cold an raining here so I'm killing time.

 

[nordvindcrew]

rowing stations

First, don't be decieved by anything you read in almost any book. The simple rules of rowing station measurements aren't worth a damn unless it's for a simple flat iron skiff to be used as a tender. Dimensions are particular to each boat and oarsman. As beam increases, oarlocks move further from the thwart. keep your thwart as low as possible while still being able to sit comfortably. Mock up your station to see that you can get enough travel to get the blades far enough forward on the catch and still get a full pull for a long stroke. Our 20' boat has a spread of 50" at the locks, we row with 8'9" oars with 27" inboard. back of thwart to oarlock is in the range of 20" (a little less for me, more for my brother). A common mistake is to have too little vertical distance between the thwart and oarlock. This results in your legs interfering with the oar handles on the catch stroke. The end result of that is the oars can't be raised high enough out of the water to clear waves with the natural result of "catching a crab" oh the catch stroke not to mention slowing down your cadence tremendously, Our foot stretchers are placed so that our knees are slightly bent on the catch and fully straightened on the pull. The thwart is wide enough to allow a bit of sliding on the pull to give a bit of sliding seat effect as well as allowing changes in seating position to ease a sore spot in a long race or row. All trial and error, and all of the boats we have built wind up with the gunnels looking like they have been machine-gunnned from the multiple station changes. The 19' Jersey skiff we built was almost un-rowable wheen we launched it. After several changes including thwart height and placement as well as oarlock position we finallt had a race winning boat tailored to our needs. That's why we don't build museum quality boats: we don't have to worry about making the changes. Hell, we even cut one full strake off the sheer of the Jersey skiff to get things where they needed to be. Good luch, stay in touch. Jeff

 

[sailing canoe]

rowing position

Do you mock up the position in/on the water? Getting tangled up with your own legs was just what I was thinking of. But it also seams as if you get the oar locks too high, your hands will be really high on the pull - not efficent. Wave clearence vs efficency. Ofcourse the competetors think those holes are for lightness. Very intimadating

 

[nordvindcrew]

mock up

We've always done our first mock up on dry land after we've floated the hull to find where we need to sit fore and aft to get the boat balanced on her lines properly (still a question on that; we've moved weight drastically fore or aft and found that the boat actually rowed easier, if not faster, in some extreme degrees of trim). A board and some blocks for the thwarts and some clamps to hold the oarlock sockets to the gunnels. When it feels right, we record the measurements and build from there. Usually after rowing for a while (days, weeks months) it might become obvious that some small change will help, and an oarlock or stretcher might need to be moved a bit. A change of a little as an inch can make a huge difference. Just as an aside, height of pull is also up to much debate. We pull very high, just about chest level so we can lean back into the pull with our upper bodies then use the resistance of the oars to pull ourselves upright to lean aft for the next catch. This works for us with long oars, a long pull and a relatively slow cadence. We do work hard at pullinng a snap at the end of the stroke as Charmac suggests. My GPS always confirms that this is good for 1/10 of a knot

 

[sailing canoe]

chest high

humm well that sounds about right and very pragmatic. Good name for your boat - in Norse ofcourse. How high is chest ht. Bottom rib cage? middle ? etc. For the strecher - do you just put on the floor of the boat? Which then makes me ask what is the freeboard at the rowing stations? Higher freeboard brining the oar handles higher on the chest. One of the best hints I have come across for appliing power is to have your butt float off the seat on the power stoke. The results of this would obvously depend on where your feet are -ht wise- with your butt.
On another topic. How much rocker is too much? Earlier in this thred you mentioned the importance some rocker in the bow. Is the rocker penalty hydro -drag or mostly tracking ability. I can imagine that with exxttreammm rocker the boat would hobby horse with each stroke. Care to put some kind of number(s) on it.

 

[nordvindcrew]

rowing station

Ok, for me chest high is this: bring your fists into your chest so that your forearms are parrallel to the floor. this or a bit lower is right for me. my pull brings my hands to within about 6" of my chest at the finish; although some times we stretch the pull a bit further to get a bit more power. Lenhth of pull is another compromise. Greatest power is in the short section of an arc fron 20 degrees forward to 20 degrees aft, or less. Unfourtunately, this creates a very short stroke and a very fast cadence. If you can do that, fine, if not, do a longer slower cadence with that SNAP at the end.My stretcher is a piece of 1"X4"X 18" mahogany that is mounted about 3-4" above the floor. It is set at an angle fore and aft that is confortable for my feet when I am resting on the thwart. Width should allow you to have your feet well spread if necessary to stabilize yourself in rough water. I'm not so sure if your butt should lift off the thwart on every pull. We stay planted on the thwart to maintain good contact with the boat and not get off to one side of the thwart or another. We find that our boats do some self-steering if weight gets shifted to one side or the other ( handy in a river race where there are many tight turns)Only on very rare occasions do we get our butts off the thwart: at the starting dash for a few yards to get up speed quickly, or if we hit very tough wind or wave conditions. I mentioned the hazzards of that a while ago: the risk of launching off a big wave or missing a catch and landing on your back on the floorboards. If I was going to row that way, I'd definately make clogs of the type shown by ESTAGGS in a much earlier post. More often, we just go into a faster cadence for awhile to get through whatever the problem is. What type of boat do you have or have your eye on, I'm sure that there could be some helpful feed-back from forum members. Read MELONGS' posts in this thread to get some very good ideas about what he has rowed with good results.

 

[sailing canoe]

Ok I make that about the bottom of the rib cage. I re read all the posts. I should have taken notes. There is a lot of information to be distilled out of there. I wonder if its possible to see the drawings that Tad Roberts sent you. I have been following His Shipyard Raid and hope to do it as soon as I get a boat built. It is a low wind event so rowing boats allways do well. As you might have guessed I want to build a sailing canoe - have wanted to build it for more years than I care to admit. It has a lot of rocker and overhang. This makes for a short water line for its length and I suspect this is further compromised by the rocker. While I dont need to be as commited to the rowing angle as you are, I do want it to row well and sail really well. Some of the shipyard raid boats must have been hell to row. Anyway its not going to be a dedicated rowing boat. But of course now I want to build one. I like the Herreshoff earlier in this thread - stretch it out a bit. Love those Cornish Giggs and the General Lafeyette (are the plans available?)