Re: [Paddlewise] What a drag

>I understand that you couldn't find anything on "changing the heel" but
what
>about "rocking fore and aft and side to side"? Also, what type of boat was
>Ford discussing? If he was talking about a slalom race boat (very low
>volume), I would think the already high drag could be multiplied greatly by
>a side-to-side rocking (not a one time change of heel).
>


Actually I was considering the side to side motion as well. I could not find
anything on that either. An interesting aspect of this involves paddling
across waves. We promote narrow boats for seaworthiness because they can
easily roll to maintain a more vertical orientation while condemning wide
boats that follow the slope of the waves. Thus, the narrow boat gets rolled
with the passing waves relative to the water although it rolls less relative
to the horizon. The wider boat rolls less relative to the water although it
rolls more relative to the horizon. Poses an interesting possibility. Could
a wider boat actually have less resistance than a narrow boat? (I can hear
Ralph gloating from here :-))

As for the fore and aft pitching ( here I confess I was confused since the
quote from the original post said, "A barely visible wobble or bob, say
>one-half inch, is like dragging a coffee cup-sized anchor on each side of
>the boat."  I did not think of fore and aft changes in trim since it is
normally  called pitching.

There we have studies showing that fore and aft pitching does slow the boat
from studies done on rowing shells, ships, etc.  How ever, for sea kayaks a
lot of the what might get perceived as pitching (at least in smooth water)
may come from changes in trim due to the acceleration and deceleration of
the boat. These changes of trim do not appear to cause increases in
resistance. Admiral Taylor says the change in trim is a symptom of speed and
not necessarily a cause of increased resistance. We have to contrast this
with rowing shells that experience most change in trim due to shifting of
weight (sliding seats) and not due to speed variations.

I suppose some paddlers might bob back and forth but I have not really
noticed it. I will certainly watch for it in the future to see if it occurs.

Cheers,
John Winters
Redwing Designs
Web site address, http://home.ican.net/~735769





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