asymmetrical are swede form | Page 3 | SouthernPaddler.com

asymmetrical are swede form

john the pom

Well-Known Member
Jul 30, 2007
345
1
Queensland
Never said it would propel a boat, just reckon it would more likely help a bit than slow it. Anyway your scientific rebuttal was based on Ginger Rogers. YOU can't talk :roll:
Roger if you cut the pointy bit off the back while its in the water you won't have to paddle at all. It will go quite quickly. :lol:
 

ezwater

Well-Known Member
Feb 22, 2011
50
0
Kayak Jack said, " A blunt [stern], like say a transom for an outboard motor, will leave a heck of a stream of turbulence (read drag) behind it. As it gets narrower and sharper, that turbulence and accompanying drag are diminished. It becomes more hydrodynamically clean and streamlined."

That's sort of true, but we were talking about whether to make the stern long and slippery, or to invest in more length and slipperiness in the bow.

On the blunt stern, have you heard of the Kamm effect? At one time, a really slippery car had a long, tapered stern. Kamm discovered that the tapered stern could be chopped off, and that the drag wasn't much worse than that for the lengthy (and impractical) original. The Kamm effect is part of the design for the back end of most of our modern sedans. The turbulence fills, and in a way replaces, the space that could have been occupied by a long taper.

As to whether experts have or haven't agreed on the swedeform configuration, if there were an alternative, don't you think that at least three decades of marathon canoe designers, and marathon kayak designers, would have discovered it? The superiority of swedeform for the fastest human powered paddlecraft is widely accepted. Have you seen Navy warships that weren't swedeform? All I was doing was trying to help you understand it. I guess I failed, but that's OK. Racing improves the breed.

If one wants to design a fast displacement hull, one will find that shortening the stern taper and lengthening the bow taper will pay off. Why is that?
 

tx river rat

Well-Known Member
Feb 23, 2007
3,043
2
Waco Tx
There is a lot of difference between air flow and water flow such as the car you mentioned.
I agree I like the swede form best but even a lot of the sperts will tell you a fish form is faster.
Power boats (navy ships ) have a whole diffident set of things to deal with that have very little bearing on paddle craft .
Basically I agree with most of what you say.
Here is something you can bank on ,there are so many variables to designing a small human powered water craft it is nearly impossible to make a flat statement about design.
Ron
You want see me build a boat without being asymmetrical swede form if I am looking for performance.