I have noticed that some solo canoes seem to take extra weight almost in stride,while others of similar(sometimes even larger) volume turn into instant slow slugs. I remember a beautiful Mad River Liberty I tried with extra weight that I kept looking back to see if I was towing something! Can anyone make sense of this for me?
Turtle
I’ve stopped making sense, but there’s
a relatively narrow depth range for hulls where they are most efficient at parting the water smoothly and allowing it to return again. A heavier load puts a hull beyond its optimum range. Maybe CE Wilson will stop by and comment on this.
Also note that some hulls NEED a proper load to be at their most efficient. When too lightly loaded, their ends are not engaged, their sides don’t part the water in the best way, and they almost skitter, being harder to control.
That would be the Wenonah Voyager.
Another Question
This may or may not be related to my original question,but the first reply reminded me of it.Is a canoe faster/easer to paddle with the bow well in the water to cut the water. My Osprey seem to be faster trimed that way even though it is much harder to keep straight.
Turtle
Many
racing canoes are designed to run bow down. I built a woodstripe 4x33 cruiser that was designed with a 1/2 inch rear rocker. I guess if those wacky folks in lycra and cotton shirts want the canoe bow down it must be demonstrably faster. I don’t know about kayaks, but suspect with the narower entry lines there are other factors involved
Indeed my experience too
with the Osprey,
especially when lighly loaded.
I asume it has to do with the asymmetrical shape
that when trimmed a little bit bow heavy
has a better shape for speed but less for tracking?
probobly
– Last Updated: Dec-27-09 7:47 AM EST –
yeah Dirk, I suppose that it also the rear paddle to steer by draws and sweeps, leaving the more powerful paddler to continue straight strong power strokes. In solo Race cruisers I hear that the successful racers are sliding back and forth besides healing to steer. I do not know about race solo's first hand since I never built one, nor saw plans for one. In addition I am the worlds worse solo paddler ;-)
Charlie
Denver NC
trim
the old racing boats generally ran bow down the old c 1s were like that. most new designs both c 1 & c 2 do not require the bow down some of the 327 boats like the bow up some. you really have to playw/trim in each boat
Worst Paddler??
Charlie,
You aren’t the worst solo paddler, but you might be the worst speller in the printing trade.
I’ll agree with ole 98 that trim needs to be experimented with in any boat. And with different paddling teams in the same model, the ideal trim may be different. Has a lot to do with our less than perfect
paddle strokes. Each of us has some quirks in our stroke, be it a stroke that has some sweep, or just more power than our partner. The trim can offset some of those quirks, and help the stern paddler keep the canoe on course at speed.
Big differences in paddler weight cause handling changes that aren’t all offset with level trim. Has to do with where the weight is located relative to center of mass and gravity. Remember how WW tandems put the two paddlers very near the center of the canoe. Keeps the ends light and lowers polar momentum. In marathon canoes we like to have the paddlers near the narrow ends for better reach. We don’t worry about having the ends light for big waves and aerated water. But a big guy in the bow will make the canoe run deeper in waves and that will affect speed.
And every stern paddler has a separate idea of what handling feels best. Some are happy when the bow is light and moves during corrections. Others like the bow stuck in the water and the stern moving around to make the course corrections. And others want the ends to rotate around the middle. And some use all three setups depending on the water.
And thankfully we don’t all drink the same beer. Happy New Year,
Bill
very simply put
for speed the boat should move as little water, as little distance and as slowly as possible.
a sharp boat (canoe or kayak) with a sharp entry into the water and gradual lines taking the water as evenly to the widest section as possible and then back will render the best speed.
a 19 foot long kayak cutting water with a sharp entry and moving it 9 or 10 inches out over ten feet then bringing it back over the next nine will be a fast boat.
this boat would be 19 feet by say 20-inch beam.
a sixteen-foot boat with rocker and a 24-inch beam would move more water much more quickly to attain the same speed carrying the same weight.
a little weight may increase the water line enough to offset the increased displacement.
ships have bulbous bows for a good reason
i paddle a capella, not an extremely fast boat but i don’t need that much speed as paddling is social for me.
epic makes rockets, i gravitate to valley, ndk and other greenland type boats.
basic thing… water is lazy so if you move it as little as you can you will go farther and faster.
hope this helps.
effect of weight
I’ve paddled a bunch of solo canoes with and without a 70 pound lab and have also noticed how some boats handle extra weight better than others.
I would guess that one factor is how the shape of the boat at and below the waterline changes with load. In my experience the Swift osprey (a favorite overall) was very sensitive to the additional 70 pounds of my lab…and I think the extra weight pushed the bow of the boat into the water wherewas it would normally skim just at surface level due to the rocker. You could hear the bow wake with the extra weight, and the boat got way slower. Most boats I’ve paddled seem to like extra weight…my Kestrel could take 260-270 easily (rated max is 250) and the boat remained very fast and efficient.
rocker
a boat with any rocker will slow down substantially when you add weight. long thin canoes or kayaks will be less effected.
ANY rocker? Actually I have never had
a boat WITHOUT some rocker, and nearly all my boats get a little faster after adding a moderate amount of weight. That’s because until that weight is added, the bow and stern are not fully engaged. Adding weight increases effective length, and cuts the amount of correction needed.
I agree that long, zero rocker canoes are fast, and are not much affected by added weight, up to a point. But I’m puzzled that you think adding weight to a rockered boat would NECESSARILY slow the boat.
wasn’t there a thread last year
about rocker and speed and the consensus amongst some very knowledgeable people that there was no correlation?
There’s no simple relationship, but
one can’t expect a high rocker boat to be “fast.” The fastest boats have little or no rocker.
exceptions
Fastest boats may be zero rocker long/skinny missiles like surf skis but I’ve had a bunch of “sport” solo canoes and boats like the Blackhawk Zephyr and Shadow 13 seem like apparent exceptions to the rule…very high rocker, short boats that can be driven to speeds beyond almost all other sport solos. My Zephyr could (easily) be driven PAST hull speed and while the bow wake was noisy the boat just flew…faster than most tandems, way faster than an Osprey, faster than any of my Bells and similar but maybe even a touch faster than a Hemlock Kestrel.
physics
For a car the drag force equals the drag coefficient (a factor determined by the shape), the frontal area exposed to the fluid (air for a car, water for a canoe), the density of the fluid, and the speed.
The physics must be similar for a canoe.
So when you add a load to a boat two things change…the frontal area and the shape factor.
I would think that as you add weight to a zero rocker boat, the frontal area would increase less than a boat with rocker and probably more importantly as a zero rocker boat rides deeper in the water due to weight I would think it’s shape factor would change less than a boat with rocker. And, I can easily imagine that the shape factor and how it changes with load varies a lot among boats with rocker. Plus we know that waterline length improves speed so as was stated before this effect probably favors (and varies a lot) among boats with rocker. As I mentioned I am sure that my Osprey did not like carrying 275 pounds and having it’s (blunt) bow pushed into the water…it ruined the shape of the boat’s frontal area.
Skin friction is important in canoes
If you have a canoe with lots of surface area in the water it requires a good bit of horsepower to drive it. I cannot drive a Prospector 16 to anywhere near hull speed but I can drive a shorter(less capacity) boat to hull speed.
Yet men can drive a Shadow 13 way over hull speed simply because of their stregth.
I dont think it has anything to do with rocker and everything to do with the motor.
What do you mean by very high rocker?
A 60 foot 8 oared rowing shell has a surprising amount of rocker. It works because of the “surge” progress through the water. But you’d never call a rowing shell a high rocker craft.
High rocker whitewater boats aren’t fast. They can accelerate fast, but that’s it.
I assume the boats you are talking about have a surprising amount of rocker, but I kinda think they fall well short of the amount of rocker I have in even my fastest whitewater boats.
physics
Frontal area has something to do with drag, though wave making and skin friction are much higher percentages of the drag on any boat. With a highly rockered WW canoe adding weight will increase the skin friction considerably since much more of the boat is in the water while it may actually decrease wave making drag by lengthening the waterline length slightly. Hull design and drag is a moving target and not easily simplified to something that can be easily explained in one of these reply boxes. There are several good books on boat design, suggest going to your library and reading up on the subject.
Or for that matter, go to http://www.kayakforum.com/
and read Nick’s excellent article on kayak design that’ll answer many of these questions.
Bill H.