Clicky

pirogue with no rocker

jdupre'

Well-Known Member
Sep 9, 2007
2,167
19
South Louisiana
Hi, all. It's been a while since I've posted anything. I'm getting the itch for another pirogue and am going over designs in my mind. Has anyone built a dead flat pirogue, i.e. , no rocker.

This is my thinking. When a pirogue with rocker goes through the water, the front 3 feet of the bottom presents a small "hill" that the boat tries to climb. It obviously can't climb the hill so that water has to be directed almost straight down, slowing the forward speed. With no rocker, the thin bow still splits the water to each side, but there's very little water directed straight down. Now , no rocker might cause other problems like turning difficulties and sliding over obstacles.

I'll have to go back and look, but maybe Tx river rat's "Ugly Duckling" had no rocker.
 

Kayak Jack

Well-Known Member
Aug 26, 2003
13,793
135
83
Okemos / East Lansing Michigan
In quiet waters, a boat wirh a flattened bottom can be OK. In waves, they are between bothersome and dangerous. Displacement hulls - ones that stay down in the water, and don’t climb up onto a step - are always pushing water. Under water, square corners that were easy to build, work against the paddler. Rounder, sleeker shapes do better jobs of moving the water. They move less of it for shorter distances; less power is required.

Would it break any rules if the bottom had a slight vee cross section? Sideways rocker instead of longitudinal rocker.

just a thought.
 

jdupre'

Well-Known Member
Sep 9, 2007
2,167
19
South Louisiana
Jack, a vee bottom wouldn't break any rules, just complicate the build a bit. I agree that rounded corners work a bit better, but that's almost impossible with the flat panels of a pirogue. I slightly round the corners at the chines and that works pretty decent. The Swamper is done that way and is a really nice paddler.
 

jdupre'

Well-Known Member
Sep 9, 2007
2,167
19
South Louisiana
I may, when the time comes. What's the latest with the Photoshop dilemma? I refuse to give them even a nickle a month to handle my pictures. Can we post pictures directly from our computers in a post here?
 

oldbuffpilot

Well-Known Member
May 13, 2014
398
12
77
Central Kansas and Central Texas
I see you figured the picture post out real quick! I use an app called photo and picture resizer if I have severl pictures.
ffor a while I used postimage but some one figured out it came with complimentry pics of half dressed girls. o_O
 

beekeeper

Well-Known Member
Mar 4, 2009
1,645
35
Wouldn't water directed to the side also create drag that resists forward movement?
No rocker may be faster, but in the "real" world there is probably a reason most pirogues have "some" rocker.
 

Kayak Jack

Well-Known Member
Aug 26, 2003
13,793
135
83
Okemos / East Lansing Michigan
You’re right, Andy, just like a plane moves air, a boat moves water. The less we move, the better. Pushing it sideways, up, or down generally takes less energy than if we move it forward along with us.

But, I’ve got a feeling that in a fishing boat, other concerns are more important than speed?
 

jdupre'

Well-Known Member
Sep 9, 2007
2,167
19
South Louisiana
Well, the pirogue we know today was designed for the waters where I live. It has to go over logs and debris, and be able to nose into the slushy banks of bayous so you can get out easily. Almost all boats are location sensitive, and I've found the pirogue to be just about perfect for these waters. Some boats do some things better, but the pirogue does most things very well. The only thing I've found it doesn't do well are 2 foot waves with whitecaps. Now THAT will definitely get your attention! Don't ask me how I know that. ;)
 

jdupre'

Well-Known Member
Sep 9, 2007
2,167
19
South Louisiana
Your answer may be some where on this site:
http://www.greenval.com/shape_part3.html
Bee, I've read everything on that site a dozen times over the last 10-12 years. It's about the best info out there. The takaway for me was the fact that a designer can slave for a year tweaking a design to increase performance by 5% ( actually a BIG improvement) and the average paddler will not notice the difference. One average year of bottom scrapes and damage could easily negate that improvement.
 

jdupre'

Well-Known Member
Sep 9, 2007
2,167
19
South Louisiana
This rocker thing has got me thinking.......always a dangerous endeavor. :) The average canoe and kayak normally draws about 3" to 4" of water.. An inch or two of rocker might make a big difference in that scenario. Most pirogues I've been in draw maybe half that, so over an inch of rocker may not be really necessary. Let me stew on that some more.
 

Kayak Jack

Well-Known Member
Aug 26, 2003
13,793
135
83
Okemos / East Lansing Michigan
There’s a different focus in the minds of racers and recreational paddlers. Races are almost always won in the 1%-2% range. The winner was 1%-2% faster, and the second place racer was only 1%-2% slower.

In our world, that small of an amount of time means next to nothing. Handling, carrying capacity, ease of lifting to load or portage, etc. are far more important than a few minutes or seconds.

Now, if chocolate ice cream were involved - THAT would be a different story.
 

Kayak Jack

Well-Known Member
Aug 26, 2003
13,793
135
83
Okemos / East Lansing Michigan
Joey, for a given weight of boat, paddler, and cargo, say 300 pounds, all boats of all designs will displace the same 300 pounds of water. The design of the boat just dictates what shape that “ hole in the water” will be. That’s the static situation.

In the dynamic situation, the design affects how much effort has to be expended to move that hole THROUGH the water. Cause in simple words,that’s what we’re doing. We just shove around a hole in the water. Sometimes logs, rocks, etc, try to hide in, or sneak into that hole. Alas, fish never do.
Though, I once had a massasauga rattler try to. He and I had a peeing contest, and I could pee farther than him, so he went around instead of through.,
 

Kayak Jack

Well-Known Member
Aug 26, 2003
13,793
135
83
Okemos / East Lansing Michigan
Murphy’s Law as it applies to displacement hulls:
(1) Everything produces drag.
(2) Only a few things produce thrust. And even they too produce drag. But, not as much drag as thrust. Hopefully.
(3) Rule#1 always applies. Rule#2 applies some times.
(4) Never forget rule#1. Mother Nature certainly doesn’t.


(A displacement hull, is any slower moving hull that does not rise part way out of the water onto a reduced area “step” for less drag and more speed.)

By the way, all four rules also apply to almost everything else in Life. That includes tricycles, bicycles, motorcycles, cars, trucks, planes, and people. Hershey bars, and other good chocolates, may be an exception. Unless you're careless enough to let one of them melt in your pocket. Then, you are producing more drag than thrust. Much more. sigh
 
Last edited:

oldsparkey

Well-Known Member
Aug 25, 2003
10,256
90
77
Central , Florida
www.southernpaddler.com
All I can say is that a Pirogue will go threw places a canoe will have trouble with. One trip threw the Okefenokee Swamp we started on the North East side and in those 4 days (5 nights ) we had to maneuver the Bone Yard. It's a section of the swamp which is littered with fallen trees which are underwater. They are everywhere from a few feet to really shallow and you have to get threw the Bone Yard to get to the next campsite.
I was paddling my pirogue and had no problem in the bone yard , I did scrape a few of the logs but nothing to hang me up or slow me down. The guys in their canoes had a hell of a time with hanging up. The worst canoes were the aluminum ( Grumman ) ones with that short keel that Grumman puts on the bottom of their canoes. The fiberglass ones could wiggle their way over most of the logs which left some tell tail color of the last canoe that went over them on the logs.