designing a fast rowboat

oars

My oarlock beam is 51" oars are ( i think ) 9'-2" reason for confusion is that we've changed the grips and shafts and never remeasured. With the oars out to the buttons and held horizontally, there is about a 2" overlap. When we're rowing the overlap goes away so we don't have to pull with our hands overlapped. Our oars are pretty long, but we are used to them and the long pull they provide. some people would hate our set-up. Get in your boat and clamp a board with the locks on it and move it back and forth with a couple scraps of wood the length of your oars untill everything works so you get a good catch and the pull ends up where you want. Don't let your pull go too far back; some is good but too much hurts as you lose efficiency at some point. Try to have your pull be able to end with a snap. The final snap will add greatly to your speed. Don't over do the snap or you will tire yourself.

 

oars

Thanks for the comeback, according to the formula your boat needs 8'4" or so oars. I kind of figured that the formula was just a starting place, when I was a commercial salmon fisherman one person swore by bait and another swore by lures, whatever works for you.

 

oars

I've got 10 birds mouth shafts made out of Alaskan Yellow Cedar. I've never gotten around to laminating the blades. Shoud get on it as the shafts are very light with very little flex. I was going to make spoon blades but now am leaning towards straight blades to work on learning to do the dory stroke. The problem I'm running up against is how to protect the shafts. Leather might not do it. Maybe something like the 8 man shells use?

 

oars

How thick of slats did you use on your oar shafts.

 

oars

I can't remember for sure, but without measuring, i'd say about 3/8" thick X 3/4" wide. I should have made them smaller because the oar shafts came out to be a bit more than 2" in diameter. I glued them with Pl 2000 construction adhesive so I'm not sure how they will stand up to use. They are plenty strong;light too although I've never weighed them. Far lighter the my aluminum shaft oars. I put one on 5' wide supports and hung on it (170 lbs) and it hardly gave at all. Maybe too stiff. I need to get some 1/8" marine ply to laminate the blades out of. just can't seem to get to it. The distributer is in Somerville which is a miserable place to get to from my house. I've really got to get it done because our oars are killing us. I've got a mold all made up to laminate the blades with a moderate spoon: 1/8 ply, fiberglass and epoxy then 1/8 ply. bond to shaft and then cover with light cloth and epoxy. Supposed to be just about bullet proof; light and strong. More and more boats are using the type of locks and oar sleeves that the big shells use. They have a button stop built in and a flat side to align the oars against the pins so that the oar goes into the water at the same angle every time. We rowed the great river race and finished 7 miles in 1:09:05. a distant second to a Herreshoff Althea that finished in 1:05:42. The boat pulls to starboard a little bit and we wasted too much time correcting for that. It feels like a small ballast bag of around 10 or 15 pounds in the stern will fix that. The other possibility is a small skeg or a small fixed rudder. Time will tell. For over 1/2 of the distance, we held speeds of from 6.7 knots to 5.9 knots. Not enough stamina to do the whole race that way but that will come as we get back into shape. The greatest benefit was mental: there was almost no stern wave. It was such a releif to look behind us and to see that we weren't dragging half the Atlantic Ocean behind us. Brother Dave is encouraged and it looks as if he's mentally getting back into the competition mode. It will be good to have him back

 

update

Nordfiord is starting to shape up. We played around with a ballast bag and found that 20 pounds as far aft as the rear bulkhead helped settle the boat down a lot: far less tail wagging and quite a bit more stable. The foot stretchers need more work. Currently only our heels are supported. If we make full foot supports, we hope it will cut down on leg fatigue and cramping. We also need to move the stretchers forward a couple of inches. Other than that, things feel good. At 5 knots there is almost no stern wave and no noise as the bow cuts through the water. Another addition will be a small skeg shaped rudder that will be set up with a detent system so it can be set and left alone or nudged by foot and set to a new angle to offset wind-cocking. The rudder will be very small, probably 10-12 square inches but it should be enough. Right now I'm scrounging up materials to make a prototype to check things out. If it works, I'll have the real thing welded up out of marine grade aluminum.

 

Good to hear it's coming along. You definitely want a stretcher for the balls of your feet. Attached is a pic of my boat in Maine at 5-6 mph.

 

slick

Looks real slick. I think our boat may have a little less of a stern wave but I'm not sure. Is that a front-view mirror on the little mast behind you, and if so, how does it work out?

 

The mirror, a la 56 chevy, works better than anything else Ive tried, but does not give a wide field. A channel marker may suddenly be right next to me but I won't hit it. I'd line up the stem on the back of my wife's kayak and she would negotiate the rocks, moorings, and lobster pots as we toured. Pic also shows my stretcher.

 

rear view

Some of the guys I race against use an eye-glass mounted rear view. I tried it but the motion drove me crazy. How about a regular automotive rear view or the fish-eye wide angle type? It looks like your stretcher is just a piece of flat stock mounted high enough for the balls of your feet to rest on it. We're thinking of something more like the collegiate shells use but not using clogs to tie our feet in. I've got some foam floor mats that I'm going to cut out to make a contoured seat that will keep me centered in the boat; it might help. I got a kick out of the picture of your boat. It is very similar to the Nordfiord. yours is rounded while mine has chines, but all in all they do seem to look a lot alike. We are slowly getting back into a regular rowing routine: did 4 miles last Sunday. If we can get on the water every Sunday and build up to more miles then we might be back in competitive shape.

 

My Club Benfleet yacht club, just ran a new race Saturday the 3rd, the Round Canvey Island race. Bit of an experiment as it was billed as a Rowing race with sail or sail & Oar class as well.
We had 15 entries with rowing boats ranging from two sliding seat coastal fours a Fisa coastal pair, four oared Gigs, 18ft Skiffs & a Gravesend watermans skiff.
Sailing entries were a Wayfarer, Tideway, & three luggers. Its 14 miles dead on with 4 distinct legs of 3 1/2 miles, two road bridges & two tidal barriers.
Due to the shape of the island & a narrow tidal window to hit round the narrowest part we went out of the creek against the tide for the first leg this takes you out into the Thames estuary & it was very choppy indeed.
Due to one of my crew dropping out through injury i borrowed a lugsail rig from my wifes dinghy & stuck it on my 18ft Skiff the night before
We ran a staggered start with slowest boats away first & everyone got a start time & finish time.
Sailed the first leg & then had the second leg a hard 3 1/2 mile pull to windward. third leg also had to row & half the last as well.
Interesting thing was how close most of the rowing boats were together at the end with minutes between them. My crew Sheila did very well having never sailed a boat in her life & is a damn good rower!
Fastest rowing boat was Gravesend RC ladies who did it in 2hrs 15m 10s
The idea of a rear view mirror appeals as i now have a crick in my neck from looking over my shoulder to go with all the other aches & pains!

 

The reputation of the Bank dory is pretty much a myth. Their design had more to do with being cheap and easy to build with available materials and being stackable on deck, than with any inherent seaworthiness or speed. The Swampscott dory was considered a vastly superior design. But I think neither is what you are looking for. I think something that looks more like a wide canoe would be a better option. Something fairly narrow at the waterline, then widening out to something like four feet. John Winters designs his canoes with little or no rocker in the stern half of the canoe, but a fair amount of rocker in the front section. The theory being that it works like an arrow with fletchings. The rocker in front gives some ability to turn, but the straight keel in back lets it track well too. I think this would be a good plan for your boat.

 

race time

I don't think I'd want to mess with that ladies crew. That's a wicked fast time for 14 miles with some tough up wind work thrown in. It does amaze me that so little seperates the fastest boat from the slowest. It comes down to how much grunt you're willing to put into the oars. A good boat is needed but will power wins races.

 

Round Canvey Island...

The women were cheating! They used a sliding seat coastal four! My crew was very happy to come third behind the two coastals, posting 2:28 over the 14 miles in the gig.

Keith's boat, SeaX (I think!), is fantastic, btw. Beautifully made and some great finish.

My first Great River Race for us this Saturday (17th). 21 miles heading west up the Thames, and the weather forecast says rain and a strong westerly... Great!

Pete

 

Thanks for the compliment Pete, actually there were several crews missed the first turning mark out, someone put it 400 yds too far east, in the end we didnt disqualify anyone as it was our fault. Next year we will make sure its in the right place! Re the Great river race 330 entries this year makes it the biggest ever. If the weather is as forecast it will be a killer, last years was similar & it was very rough indeed below Tower Bridge & through the city.
BYC ladies crew are in my Skiff, she has been named Zev , those who ever saw Lexx the Dark zone will know where the name came from.