As Mike points out, one parameter does not make a boat. Drag numbers,
prismatic coefficients and other calculated numbers are only effective
if you are comparing several boats of like type, and also have the
ability to compare the real-world paddling performance of the same boats.
Line up four 17' kayaks (assuming they are the proper size for you) from
different top manufacturers (or kit builders), measure and plot all the
parameters as Vaclav has done here (BTW, I think he infers using the
displacement weight as found on another page in his calculations), and
then paddle each over the same course, same conditions, same heart rate,
and see how the numbers shake out for real world speed, load conditions
and stability.
Now change the course and make it choppier or windier, bigger waves,
etc. I'll bet a dime the numbers fade into oblivion compared to the
feel that certain boats will impart.
Example - from a performance standpoint, the CD Stratus18 is a very fast
boat with very good 'numbers', but it is a handful as a touring boat - I
wouldn't want to be out in a blow on Lake Superior trying to make camp
in that thing. I'd much rather be in a Caribou or Solstice GTS, which
have much worse 'numbers'.

Marsh


wrote:
Michael Daly wrote:
wrote:

I'm not sure about the loading but he made the argument that one man
trying to paddle a double alone would not gain an advantage from its
extra length. It would actually have more drag.
Then maybe you should have pointed that out. I looked at your subject and
commented on the comparison of the 15' and the 17'. The double is 18'6".

It is widely assumed that longer kayaks are faster. Folks like me are
frequently pointing out that this is not always true. One person in the double
compared to one person in the single shows such an example.

Trying to express the performance of a three-dimensional object in water using a
single parameter will always fail.

Mike

The 15.5ft boat has the lowest drag on the page. I don't know what he
presumes about loading/displacement.