penetrating standing waves

I was just watching my DVD of the IMAX movie, Secrets of the Grand Canyon. I was watching the rafts and dories go through rapids and a question occured to me.
In rapids, there can be large waves that curl back. A common scenary for getting flipped is to hit these waves at an angle or, if they are really big, getting stalled by the back-curl and getting broached.
I always assumed that you wanted a bow that would lift you up and over the waves, and you certainly don't want your boat to act like a submarine, but now I'm thinking that too much of this might actually work against you and increase your likelihood of getting stalled and turned sideways, that you want a bow that will cut through the backcurl without getting stopped by it.
I'm wondering what the best bow shape would be. Maybe not so blunt and maybe less overhang than I would have previously thought ideal.

 

Depends... it's all´ways how the specific standing wave behaves ie, the length and height of the wave and how it affects the boat... so every rapid has it own "wave lenght" and there fore it's ideal "best" length and bow height for the boat..
BR Teddy

 

And I think bottome shape factors into this too. I've always maintained that the single chine, flat bottom is not the ideal shape. Now I feel this even more strongly.
I think you can come up with a good compromise design for the front of the boat. A tall wave with little back curl is going to call for a different shape than a smaller wave with a big back-curl, so you have to come up with the best compromise. I'm inclined to believe that what you see on dories now can be improved upon. But what is the best direction to go?

 

Generally the longest possible boat length is the best, for effiency and speed of course. But the main limiting factor in this regard is the length of the shortest standing wave it's got to go throw without compromising safety. Canoe bodied, short WL with high free board is what's used here in the biggest rapids..

 

Different boating techniques require different boats. A kayak, a canoe and a drift boat are very different shapes with particulare handling characteristics.

 

I think Gonzo has hit on an important factor. The driver and how the vessel is driven. Sure the design is important but how it's operated is just as important and more of a variable because once the boat is designed and built, that's what you have got and it needs to be driven appropriately.

-Tom

 

Well, it's just like in cycling. It's not the bike, it's the rider. But considering I dont' row dories for a living, and will never acheive the skill level a professional guide has, I need all the help I can get. Lance Armstrong didn't win seven tours because his bike was better, but he wouldn't have settled for anything but the best either.
I guess my point is there was extremely little experimenting with river dories. Probably less than just about any boat in history. Once somebody found a design that seemed to work OK, no one strayed very far from that design. I've watched rafts and dories go through rapids and have seen how they interact with the waves. I have books and videos on operating rafts and dories. I've taken my canoes through rapids with waves big enough to swamp the boat. I know how the shape of a canoe affects stability, turning, etc. The thing about a canoe is you can feel subtle differences that would be harder to detect on a dory. I'm taking all this knowledge, experience and my own intuition and I'm looking at dories and I'm asking myself, did they get it right? I think they did pretty good, but is pretty good, good enough? Lives are on the line.

 

Here is my response to the constant argument that you can't design a "best" boat.
Suppose you owned a company that made drift boats and decided that you wanted a new boat for your line, a Grand Canyon type dory. You have two designers and set them both to the task of designing the new boat. Both designs look good and you can't decide, so you build a prototype of both and loan them to a company that does dory trips down through the Grand Canyon. I think that by the end of the summer, there would be a clear winner. One boat would perform better than the other. Would that change if you went to the Selway, or Cataract Cayon? I doubt it. I think in the real world some designs are better than others.
Let's take race cars. Ferrari comes out with a new race car and it wins it's first race. It isn't likely that it is going to come in last at a different track. If they've done a good job, it is going to do well at any track. If you have a good dory design, it is going to do well on any river in any rapid.

 

Are you considering traditional designs other than the Banks dory? How about a surf dory with a little wider bottom?

I'm thinking along the same lines as you but trying to use traditional designs to improve upon the drift boat. I want a boat to float on the Yellowstone, but I might want to take it through Desolation Canyon or Westwater. Must you have a different boat designed for specific river conditions or can a design be generalized so that it behaves OK for different flows, wave heights, and manueverability?

Gary

 

Like my Dad always said, If it ain't broke, don't fix it! Why mess with a design that has worked well for over 140 years. Dories were used to run rivers by the early explorers in North America. The design has been refined a bit, but it's still basically a dory. Dories were used off shore for fishing in the North Atlantic because they could hold a ton of fish without swamping, survive the worst weather imaginable, and they were rugged. All the same good reasons for using them as drift boats, They aren't easily swamped, will survive the worst kind of water conditions, and you can beat them up bad and they still work.

 

Roger Fletcher in Drift Boats and River Dories talks about the evolution of modern drift boat designs. Considerably experimentation with the design, particularly up through 1970 or so. That doesn't mean a better design isn't possible. But it isn't accurate to say there was extremely little experimenting.

It's also worth noting that there is some regional variation in the current boats depending on the rivers. But there also seems to be more than a little bit of selecting a design based on other than functional considerations. Why have a full-blown McKenzie river boat for fishing on Michigan rivers with the worst white water being some riffles? The locally evolved drift boats which are lower, longer with little or no rocker would seem to be better suited to those particular rivers.

The "bateau" used for river running and logging had flat bottom and flaring sides but they were considerably different proportions than the bank dories used for longline ocean fishing.

The bank dories may have been chosen for that type of fishing due to their low cost and ablility to nest on the deck of a schooner rather than any special characteristics.

River dories have considerably different proportions, much wider and more rocker, than bank dories. The design emerged in the 20th century.

 

I realize that. But they were also used because of their ability to carry a load and stay away from the schooner all night (which they often did).

Yes there has been a lot of experimentation with the flare, rocker, etc. But the original boats used to run down the western rivers were dories just like those on the Grand Banks, because that's what they knew how to make.

Sure, he can change this and that, but how many changes can you make to a dory, until it's no longer a dory, and no longer a drift boat?

I guess my point is this: most boats are built for a specific purpose. Yes they can be used for other things, but they don't do the other things as well as a boat specifically designed for it. The state of the art (if you can call it art LOL) in drift boats pretty much reached it's peak a long time ago.

 

Seems to me you need self bailing capacity and ability to deform/slide rather than break/shatter upon severe impact in any dory designed for rough rivers. There are materials like polybutylene? that can take a lot of punishment because of the lubricating nature of the surface. Someone mentioned that the bottoms should be capable of being replaced easily because of the beating that is taken on wooden bottoms....

P.

 

The answer to that is: inflatables.

 

I'm interested in any references you know of besides Roger Fletcher's book on boats used for early western river runs.