designing a fast rowboat

[acp1934]

It looks like it has pretty slack bilges, like a canoe, with that & a beam of 4', I would think the beam at waterline would be excessive. What width do you calculate @ WL? Can you post a body plan & profile?

BTW several single chine dorys, resembling the Banks, but of course with less beam, rocker & lighter scantlings, have done very well in open water rowing races.

i think the canoe-like craft you're talking about in races would be the guideboats, very much discussed in these pages, but generally a 3' or so beam, rowed with overlapping hands, relatively short oars for a race boat, needing a stroke rate & speed of pull unsuitable for the original poster, who has built at least 2 boats since starting this thread.

[nordvindcrew]

to river runner, I haven't got the capability to post photos. That is one reason i note the races because there are lots of pictures of the boats for people to look at. I do some work on PRO-SURF and those computer generated images are neat but show a kind of fantasy boat that looks so good that you just want to dive in and build it. I see some issues relating to waterline beam and placement of your rowing station but can't say for sure. If you think it's a winner, go ahead and build it and let us know how it comes out. In relation to banks dorys, the Stretched Gloucester Gull is always a contender with a good crew and it is a true dory type that has been slimmed down a lot. It is a good boat for all conditions too. Keep your mind open and learn along with the rest of us travelers. By the way, good luck on your primary issue of re-designing a boat for river running. I know nothing about that and will probably offer no comments. Nord

[nordvindcrew]

we tried our 8' oars on the Nordfiord. Way too short, we couldn't get above 5 knots. it looks as if our 8'9" oars just need to have the buttons moved outboard by 2" to lower the gearing enough to be managable. I'm finishing up the 8'-4-1/2" oars. they may be too short also. The difference there is in the blade shape. the new oars have a conventional straight blade that is long and narrow and will move the center of effort back towards the boat ( I think ). Sunday was a great morning to be on the water mid 60's here in New England, no wind with only a slight 2' swell. It was so foggy that visibility was nil. We stayed pretty close to shore although the sun was visible to navigate by as well as the trusty GPS. Life is good on a day like that.

[river runner]

I know I "don't belong on this forum" because I "don't have the right attitude", but just in case some people dissagree and think I have something to contribute, here is a rough draft of a decked rowing canoe, such as might be used in ocean racing. I only spend about fifteen minutes on it, so I know there are problems with it, but I didn't really feel like spending hours on a boat that I have no intention of building myself.

[nordvindcrew]

Everyone belongs if they want to. As to attitude, that's up to you. The quick design is nice to look at but doesn't work well in real life. A decked anything make it difficult to manage your oars.

[river runner]

This is probably under the "wrong thread", but it's a design for another one of those slow rowing canoes. A two person decked rowboat for ocean racing. I'm sure you guys could design something much better, but I'm doing the best I can in fifteen minutes. I think it looks pretty good, especially considering how stupid and ignorant I am.

[DickT]

Originally Posted by river runner

This is probably under the "wrong thread", but it's a design for another one of those slow rowing canoes. A two person decked rowboat for ocean racing. I'm sure you guys could design something much better, but I'm doing the best I can in fifteen minutes. I think it looks pretty good, especially considering how stupid and ignorant I am.

I haven't been paying attention to this thread for a while but have found it very valuable in finetuning my boat. Most who've stuck with it here have built their own boats from plans, totally winging it, or something in between. I've found that fitting a fast rowboat to the the rower is critical. That's hard to do by formula, though formula is a good place to start.

Your designs look like they would behave well in the water but not would not be necessarily be fast for their length. I say this strictly from my nonprofessional guess on their apparent prismatic coefficient and the reverse waterline curves fore and aft.

I hope you don't find my comment offensive. I think we can all learn from each other especially when our ideas are tried out in actual built boats.

[DickT]

Originally Posted by nordvindcrew

we tried our 8' oars on the Nordfiord. Way too short, we couldn't get above 5 knots. it looks as if our 8'9" oars just need to have the buttons moved outboard by 2" to lower the gearing enough to be managable. I'm finishing up the 8'-4-1/2" oars. they may be too short also. The difference there is in the blade shape. the new oars have a conventional straight blade that is long and narrow and will move the center of effort back towards the boat ( I think ). Sunday was a great morning to be on the water mid 60's here in New England, no wind with only a slight 2' swell. It was so foggy that visibility was nil. We stayed pretty close to shore although the sun was visible to navigate by as well as the trusty GPS. Life is good on a day like that.

I can't get my old arms to move fast enough for oars less than 9'. If I'm trying to stay over 5 I throw my gut into the stroke big time.

Great you guys are still out on the water. I put my boat away for the winter.

[river runner]

Pitching slows a boat down. It is more of a factor with sliding seats, but still an issue with non-sliding seat boats. Some ways to attack problem:
1- Boats with less rocker pitch less, but are harder to turn.
2- longer boats pitch less, but have more wetted surface.
3- boats with fuller ends pitch less, but if this goes beyond a favorable Prismatic it could detract from performance.
4- Possibly the solution with the least amount of problems would be to give the boat a lot of flare in the ends, just above waterline. The underwater shape and wetted surface would be favorable, but as the boat tried to pitch or rock, the flare would come into play to reduce it. As I stated before, a boat with a little rocker in the bow, but little or no rocker in the stern tracks well, while still being maneuverable.

[river runner]

The weight of your oars is extremely important. You use up a lot of energy moving heavy oars. Your stroke rate will be slower with heavy oars. I had a couple good cycling buddies that used to belong to a rowing club in Madison, Wisconsin. One even did some coaching. They said that the carbon fiber oars they used for racing were so light you could grab the handle with one hand and hold the oar straight out. You might not want oars that light for ocean racing, but lighter is better, up to a point.

[river runner]

Relevant article.
http://www.pocock.com/rowing-boat-in...n/hull-length/

[nordvindcrew]

Light is right. Carbon fiber oars are an expensive dream that I may realize some day. I am trying to con some used oars out of our local university rowing programs. No luck so far. regarding pitching, the thing to remember is that in most of our races the whole boat is in the water at times and becomes wetted surface. The area above the waterline is a critical as what is below.

[ancient kayaker]

The blade of a light oar needs to be thin so it doesn't float, a carbon blade can meet that criteria. It's different when paddling; a little bouyancy in the blade reduces effort with either a single- or double-bladed paddle. A heavy oar can be balanced; a heavy double-bladed paddle is hard work!

[river runner]

Marathon racing canoes have some pretty extreme shapes, not because they are more efficient through the water, but because they allow a more efficient paddle stroke.
Working on the theory that a more stable platform to row from might allow more efficient rowing, I offer this design. A problem I see is that wide flat bottoms or pontoons actually rock more from beam waves than a narrower, rounder bottom hull. It still might work. Especially if you went to a full blown cat design rather than the "mono-cat" I've drawn. Allowed under the rules?

[sailing canoe]

Well I saw a interesting open water rowing double today. It was pure luck as the weather has been unreal - 70 degrees, thats warmer than it is most of the summer - and I just had to cut out and get on the water. At my regular launch spot I met a sales man and ex-olympic rower from Canada making a swing down the west coast delivering boats and giving demos. In the middle of the roof rack was a open water double. I believe he said it was made by Wintech but I can find no mention of it on their web site. It was about 19 ft long and relativly beamy but maybe less than 3 ft. One of the neat things about it though was that the whole transom was hinged to let the water back out. A neat idea. If I can find out more info I will let you know. I actually know the owner to be - Nick