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-   -   What do I lose by having a shorter boat? (https://www.boatbanter.com/general/44845-what-do-i-lose-having-shorter-boat.html)

donquijote1954 June 16th 05 05:08 PM



Bub wrote:
Take a long look at the necky Zoar Sport. 14 foot boat w/rudder well made
and stable. A little more boat then the Manitou. At $999 w/rudder, its not
bad.
Bub



Thanks!

Two questions: Can the padding be removed from the seat? and, Do you
get to use the rudder/keg or is it a nuisance?

I'll quote something...

'The Zoar Sport is a brilliant little boat. At 14' it is a touring boat
rather than a true sea kayak but I have found with mine that: 1) it
handles very well on fla****er, keeping close to the longer, "faster"
boats; 2) it handles extremely well in surf (force five conditions); 3)
it is solid and durable; and above all 4) it is a comfortable fit (I am
6'4" 240 lbs). Great boat.'


Michael Daly June 16th 05 05:13 PM

On 15-Jun-2005, "rick" wrote:

Again, how
does a longer kayak "overall" not have a longer waterline for
the same type hull


The original poster said nothing about "same type hulls." He
provided two overall lengths and asked for an assessment of
how the speed would compare. I correctly stated that one cannot
determine that from the information on overall length.

But for a given
hull design, it still looks to me that that will be the major
factor according to the sites I posted.


You're ignoring the data on the graph. The data comes from
Sea Kayaker magazine and clearly shows that there is no
correlation between overall length and resistance. Why do
you keep insisting that there is?

See also:
http://www.kayakforum.com/cgi-sys/cgiwrap/guille/wiki.pl?The_Myth_Of_Length

No, I'm posting web sites that state the opposite of you, not MY
opinion. Which of course you have snipped.


Try reading a book on the hydrodynamics of hulls. C.A. Marchaj's
"Sailing Theory and Practice" is a good one. You can also stop
assuming that overall length and waterline length are interchangable.

I was seriously asking for data.


I gave you some. It shows that there is no correlation between
resistance and length for 24 common sea kayaks that have been
reviewed in Sea Kayaker magazine.

Mike

Peter June 16th 05 05:30 PM

Michael Daly wrote:

On 15-Jun-2005, Peter wrote:


When two variables are correlated it means that they have
a tendency to vary in the same manner, not that there is a one-to-one
correspondence in each particular case.



Fine - I'm using the term correctly.


No, you're not. What you said before was "there is no correlation
between overall length and waterline length in kayaks."

If that were true it would mean that knowing the overall length would
not give us any hint about the waterline length - that is it would be
similar to my telling you my astrological sign and asking you to guess
my weight. But in fact the overall and waterline lengths of boats are
quite highly correlated and boats that are 18' long overall will almost
always have waterline lengths greater than boats that are 14' long. The
correlation isn't perfect (correlation coefficient of 1.0), but it is
very high (correlation coefficient is probably around 0.95). An example
graph of skin fold thickness vs. body fat, two highly correlated
variables, is shown at:
http://www.sportsci.org/resource/stats/correl.html
In this case the correlation coefficient is 0.9 indicating a high degree
of correlation, but you'll notice that there's quite a bit of scatter;
i.e. there are many examples of specific individuals who may have a
greater skin fold thickness than someone else while having a lower body
fat percentage. In the same way, there would be some scatter if we
plotted kayak overall lengths vs. their waterline lengths, but we'd
clearly see that the *tendency* is for the longer boats overall to also
have long waterline lengths.

When you compare kayaks,
you will see that some have overhanging stem and/or stern, others have
plumb stem and/or stern while others still have raked ends. Thus, you
can find kayaks of the same overall length with very different waterline
lengths. It is not automatically true that if a kayak has a longer
overall length it necessarily has a longer waterline length.


And of course no one has ever argued otherwise - you're just rambling on
debating strawmen. If you're going to use the term "correlation" then
it would be good if you knew what it meant.


Michael Daly June 16th 05 05:40 PM

On 15-Jun-2005, "Van D" wrote:

As I said, there is no correlation between
overall length and waterline length in kayaks.

Mike



I am sorry this is just drivel dressed up as an authoritative opinion.


Further info from the Sea Kayaker reviews. This shows the how much shorter
the waterline length is than the overall length for bunch of real sea kayaks.

Bergans Ally Folding 3.1%
Nelo*FW*2000 3.2%
Epic*Endurance*18 3.3%
Prijon*Barracuda 5.3%
KajakSport*Viviane 8.3%
Prijon*Calabria 9.3%
KajakSport*Viking*Ex. 9.4%
Point65N*K1 VR 9.4%
Seda*Glider 9.6%
Feathercraft K-1 Exp. 9.8%
Point65N*K1 R 12.2%
VCP Aquanaut 13.6%
VCP Avocet 14.2%
KajakSport*Artisan Mill. 14.9%
PH Quest 16.2%
PH Bahiya 16.5%
Nordkapp*H2O 17.2%
Current*Design*Andromeda 19.0%

That's a pretty wide spectrum - from 3% to 19%. Correlation? I don't think so.

Mike

donquijote1954 June 16th 05 06:00 PM

Waterline in fla****er, because in rough water the picture changes...

Michael Daly wrote:
On 15-Jun-2005, "Van D" wrote:

As I said, there is no correlation between
overall length and waterline length in kayaks.

Mike



I am sorry this is just drivel dressed up as an authoritative opinion.


Further info from the Sea Kayaker reviews. This shows the how much shorter
the waterline length is than the overall length for bunch of real sea kayaks.

Bergans Ally Folding 3.1%
Nelo FW 2000 3.2%
Epic Endurance 18 3.3%
Prijon Barracuda 5.3%
KajakSport Viviane 8.3%
Prijon Calabria 9.3%
KajakSport Viking Ex. 9.4%
Point65N K1 VR 9.4%
Seda Glider 9.6%
Feathercraft K-1 Exp. 9.8%
Point65N K1 R 12.2%
VCP Aquanaut 13.6%
VCP Avocet 14.2%
KajakSport Artisan Mill. 14.9%
PH Quest 16.2%
PH Bahiya 16.5%
Nordkapp H2O 17.2%
Current Design Andromeda 19.0%

That's a pretty wide spectrum - from 3% to 19%. Correlation? I don't think so.

Mike



donquijote1954 June 16th 05 06:32 PM



Keenan & Julie wrote:
"Bub" wrote in message
news:LUdse.19405$gL4.18313@trnddc07...
Take a long look at the necky Zoar Sport. 14 foot boat w/rudder well made
and stable. A little more boat then the Manitou. At $999 w/rudder, its not
bad.
Bub


It is a bit of a bathtub though :-)



Don't pay attention. It's only envy... ;)


Michael Daly June 16th 05 07:55 PM


On 16-Jun-2005, Peter wrote:

boats that are 18' long overall will almost
always have waterline lengths greater than boats that are 14'


Fine, but we were comparing kayaks that were only a foot and a half or
so different in length. Of the 105 kayaks on the web page of Sea
Kayaker data, the average length is 5.2m (17 ft) with a standard deviation
of 41cm (16 in). 78% of the kayaks fall within one standard deviation of
the mean length. We're not talking about huge differences in length
typically, especially since the standard deviation is comparable to the
differences in LOA and LWL.

but it is very high (correlation coefficient is probably around 0.95).


Instead of pulling these numbers out of your ass, how about some facts?

Based on the data I posted on 18 kayaks (showing percent differences
in LWL and LOA), the actual correlation coefficient is 0.79. Not exactly
tight. In terms of performance, that is a significant difference. Thus
it is not reasonable to make sweeping statements that one can predict
performance based on LOA instead of LWL.

You guys are pulling out extreme examples based on hand-waving about
theories that few of you actually understand. I'm talking about
real kayaks in the real world. In the real world, we can't reduce
performance estimates on vague physical characteristics.

Mike

Michael Daly June 16th 05 07:56 PM

On 16-Jun-2005, "donquijote1954" wrote:

Waterline in fla****er, because in rough water the picture changes...


I'm talking about defined LWL.

Mike

Peter June 16th 05 08:46 PM

Michael Daly wrote:
On 16-Jun-2005, Peter wrote:


boats that are 18' long overall will almost
always have waterline lengths greater than boats that are 14'



Fine, but we were comparing kayaks that were only a foot and a half or
so different in length.


Your previous statement: "there is no correlation between overall length
and waterline length in kayaks" made no such distinction that it only
applied to some set of kayaks that all had about the same length, nor
was it limited to sea kayaks.

Of the 105 kayaks on the web page of Sea
Kayaker data, the average length is 5.2m (17 ft) with a standard deviation
of 41cm (16 in). 78% of the kayaks fall within one standard deviation of
the mean length. We're not talking about huge differences in length
typically, especially since the standard deviation is comparable to the
differences in LOA and LWL.


but it is very high (correlation coefficient is probably around 0.95).



Instead of pulling these numbers out of your ass, how about some facts?

Based on the data I posted on 18 kayaks (showing percent differences
in LWL and LOA), the actual correlation coefficient is 0.79.


Naturally the correlation coefficient will be less if you restrict the
kayaks under consideration to ones with fairly similar lengths (all but
one in the range from 16' to 19'). In a more complete list with play
boats, WW boats, surfskis, etc. also included the coefficient would be
much higher. Since your original statement just referred to the general
category "kayaks" my estimate was based on this broader selection.

However, a correlation coefficient of 0.79 is a far cry from your
original claim that there is "no correlation" which would imply a
correlation coefficient of 0. The numbers in this case are much closer
to perfect correlation than they are to no correlation.

In the reference to statistical terms I cited earlier, any correlation
coefficient of 0.5 or higher is regarded as "high" (0.1 - 0.3 is small,
0.3 - 0.5 is moderate) and greater than 0.7 is "very high."

Not exactly
tight.


Even taking your specified subset of kayaks, the correlation is "very
high" rather than your original statement that it is nonexistent.


Keenan & Julie June 16th 05 08:48 PM

snip

So, like, shorter boats are slower eh?

Sheesh, how do you guys decide what to order for lunch? Must take hours.




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