designing a fast rowboat

north river race

The king of the river is gone. After 11 years of winning this race we were finally soundly beaten. The "Red Baron" with crew John Struzziery and Craig Robinson beat us the 6.75 miles up river with a time of 1:03:34. Our time was 1:08:25. They are in top shape, and we are in terrible condition. We finished under 1 hour several years ago, and that time remains un-beaten for a fixed seat double. Fastest time for the race was a double racing canoe with a time of 57:56 with several racing kayaks not too far behind. Weather was a definite factor with temperatures hovering around 100 degrees and very high humidity. Near delerium took hold in the upper reaches of the river where the never-ending horse-shoe curves make you think that you are coveringv the same stretch of river over and over again. A bit like the movie "Ground hog day". At the finish line there were several people with heat exhaustion and we had to help a couple of guys in kayaks so that they wouldn't pass out and tip over while they were still tied into their boats with their spray skirts. Brother Dave and I chugged down a couple of quarts of diluted Gatorade the rowed up river another 1-1/2 miles to the pull-out area. It's a good cool down time and helps to keep the muscles from tightening up. The awards were handed out at Mc Greals tevern along with a great spread of sandwiches and snacks. Several gin and tonics washed the food down then home to crash and recuperate. I must be nuts to punish myself like this and still enjoy it so much.

 

Yes, this is our previous model of double. Ruud's pages aren't updated yet.

Terho

 

... but he'll be back, right?

Any pictures? I am interested in the double canoe you mentioned since I design and build canoes myself. Always looking to learn!

I had a Groundhog Day a couple of years back; worked my way down a winding river, houses becoming less frequent, carefully noted a big buoy at the end where it opened out into a lake, checked out a couple of islands in the lake and turned round.

Was the river entrance a bit further South than I remembered? No, there's the buoy, lookes a bit more battered but I'm seeing it from the other side so press on and not to worry. Back up the winding river, houses more frequent as expected, oh! Huge surprise: somebody dammed it during the day. Er, they took down the bridge as well? Hmm.

Made mental note to buy a GPS and checked with locals, then back up the river to the lake and a bit further North to the original river, past the blasted buoy etc. Got home, but no Groundhog; no Andie MacDowell look-alike either. Longer trip than planned; why don't they have signposts at these places?

 

double canoe

for pictures, try "great river race 2010" the single canoes are very slender with the hull bumped out above the waterline in the middle to get some beam and reserve stability. The doubles are 20/22' long and look pretty conventional except that the entry is exceptionally fine and a bit pinched in.

 

miracle cure

The terrible rowers malady of EBC (extreme butt chaffe ) has been cured! My lady friend found something called Lanicane anti-chaffe gell. Tried it in the race last week and had NO problems at all. One test is not concusive, but I'm hopefull.

 

Thank you for sharing that with us!

 

big score

I made a huge score last Friday. The company that makes our decorative post caps has a huge scrap pile, so I asked if I could go through it and glean out some wood. the result is enough western red cedar to make somewhere around 2500 lineal feet of 3/8" X 1" bead and cove stock. There's a lot of milling and scarfing to be done, but that's what cold weather is for. I've got Pete Cullers' book on skiffs,and schooners as well as rowing. In it there are lines and offsets for a 20' gig that look very interesting, and a good use for all that WRC. Could those lines be stretched out by a foot or a little more without distorting the hull shape too much? Something closer to 22' would give us the hull speed needed to help get the job done. As the competition gets better and better, our 16' boat just doesn't do it for us except in a race with very rough and slow conditions. There is tons and tons of thinner 1/4" stock in that pile that would make all you canoe and kayak builders cry seeing it just go to waste.

 

help

If I get into building that gig, I'm going to need to learn lofting. Any suggestions on a book that is good for a first time loftsman.

 

You lucky *******. I'd totally commit murder for that much free cedar.

Ok yes, you can stretch the gig by just increasing the station spacing. It will work fine for this sort of boat as you're not concerned about complications like stability and sail area/wetted surface ratios. It may not be the best option though. It depends on how fast you can push the boat.

If you can push it fast enough the extra length will be an advantage since wave drag tends to climb more rapidly at high speeds. If you can't push it fast enough then you may be better with the original length, or with scaling the boat up slightly in all directions. This would give less wetted surface drag. It really depends on the speed you will be operating at and the relative proportions of wave drag to skin friction for the particular boat in question.

A 20 foot gig should have enough waterline length to do the job unless you are talking about racing in optimal conditions (which doesn't seem to be the case from your posts). If it has enough displacement to carry the two of you comfortably then I wouldn't look at changing the length. If you need a bit more displacement then increasing the size in one or more dimensions is worth looking at, assuming you want to stick with this design.

That's the next point: if you really want the fastest boat for your conditions and crew weight you probably should consider a custom design. Culler was good but there's two o's in that, not one.

ETA: Oh and if you're going to this much trouble make some really good oars. Those will help your speed and endurance like nothing else. Personally I would not use Culler's oar design as IMO they are far from optimal. Excessively flexible shafts simply waste energy. Don't believe stories about getting back the kick at the end of the stroke when the shaft straightens. The second law of thermodynamics means you can never get back all the energy you put in. It's better to not waste it to start with. This is why sculls no longer use very flexible oar shafts. It used to be fashionable decades ago with some crews but has been demonstrated to be less efficient.

 

Lofting Book recommendation

"The Boatbuilders Apprentice", by Greg Rossel has a chapter devoted to lofting that's pretty easy to understand. I'm sure there's others but that;s the easiest one I'm familiar with. Are you talking about Culler's Quitsa Pilot? I have the same book but haven't looked thru it in a while.

 

not so Deer

Sorry, I have a birth certificate, so I am only lucky. The scap pile at that company is huge! there are 1/2X1/2 strips, loads of 1/4 X 3/4 stuff and hundreds of feet of 3/16 X 5-1/2 wide stuff. All of it is going through a chipper this week. A great waste of good material. About Culler; two O's is appropriate, as even I can see some stuff that I can doesn't make sense. Does any one have lines or suggestions on a 20'-22' gig. RE length: the fastest boat in any doubles race we do is a 22' modified dory. It is rowed by two guys that are big and capable of moving it, and they do! Winning race speed is about 6 knots in most races

 

Man ! That sounds like a criminal waste of material. Well done for saving some of it . Had to do a double take on the two "O's" vs one. History rewards those who talk and write it down. As for a fast gig - the one I would like to build is "Donoghue". The boat is at mystic and is in "Mystic Seaport Watercraft". Replica's of this boat have been proven on the New-England open water circuit. Plans are available from Bob Baker"s wife. It does have out riggers which I dont think your usual class allows - (?) Nice boat. May be you should just build a fast boat and not worry about the class.
The shape of the 'Flash" boats get the beam up for good spread but keeps the water line narrow. If you find a boat that has the beam you want it seams to me that you could increase the station spacing to good effect. The boat will float higher for the same load, adding windage of course. Racing shells are of course extreamly (30 ft) long for their width - a formula that would seem to generate extra wetted surface - So I dont see that stretching a design a little would hurt much; Navel architects will disagree of course.
Greg Rossel also wrote a good two issue article on lofting in Woodenboat. Short and to the point.

 

Ok just for fun I knocked up a 20 footer in Delftship. I searched the thread for your crew weight (since I didn't have the sense to actually ask) but couldn't find it anywhere. I'm assuming a total displacement of around a quarter of a ton would be right. This would allow for two blokes at 180 lbs each, plus boat at a bit less than that, with some left over for oars and bits and pieces. On a boat like this a 20lb weight difference only changes the immersion by about a tenth of an inch anyway.

Note that I'm not completely happy with the lines yet as this is just a first go at it, which is why I'm not posting an .fbm file. Length overall is spot on 20 feet, which is pretty much all waterline. Bmax is 4 feet 3 and Bwl is 3 feet. Minimum freeboard is just under one foot. Prismatic is optimised for a speed of 6 knots. The boat has a bit of rocker towards the bow in an attempt to minimise broaching and of course in practice would have a skeg added under the stern.

I think something like this would be pretty close to what you'd be looking for. For more speed reducing the waterline beam would be beneficial (a la Cornish Flashboat) but if taken to extremes (a la Cornish Flashboat ) it gives a shape which is tricky to manage with rough water and wind on the beam. I'm not entirely sure how little stability you would be comfortable with but I think this would be a reasonable compromise. Feel free to correct me if I'm wrong (and that goes for anyone and regarding any other details too of course).

 

right on !

that looks just like what I was thinking of. I usually figure a total displacement of 600 lbs. The Culler boat is the 20' cornish gig. The Quitsa Pilot seems too extreme in the waterlines down low causing the water to move off to the sides too quickly; but, then, what do I know? I'm no Naval Archetect, just an old guy who rows a lot of miles in a year.

 

designing fast rowboat

Dear "nordvindcrew",

Noticed your thread this morning. In Nova Scotia for the summer and using the time to develop concepts for new boats. One of these just happens to be a fast rowing boat. I have considered two major differences which have made a big impact on reducing the resistance and incresing stability.

If interested please send me an EMail at "bmsyachts@aol.com" as I am not yet ready to openly expose these thoughts.