Re: [Paddlewise] Rudders redux

John wrote:
>>>>>>I know Matt won't mind my using his post as an example since I know he
welcomes constructive criticism and won't take it personally. As I pointed
out in a previous post some of Matt's arguments lacked objective support
(3,4,7,12,14 and16), some used specious logic (1,2,5,8,9,13,and 15) and some
used flawed data (6). Suitable objective testing to support these arguments
would go a long way and be enormously useful.
The important thing is to recognise that a poorly designed or built rudder
is not a suitble foundation for their condemnation.<SNIP><<<<<<<<

The subjective points above may be mostly from my own experience and
certainly they don't apply to every rudder and boat in existence or one that
could possibly be imagined to exist. They do apply to the ones that are most
common though and I've made some distinctions to show where they don't
apply. I find it hard to believe that others won't notice the same things
(like the boat banging against their leg) and be very sure of the cause. 

John has argued in the past that a paddler in a kayak has little way of
telling how fast he is going or even which kayak is faster or easier
paddling at a certain speed by feelings alone. I certainly agree. Knowing
drag/speed is especially difficult when one doesn't know the speed or the
drag--if one could get the speed fixed somehow then he could make a much
better guess at the relative drag. By sprinting I can get the power pretty
well at a constant level (all I can do for a short time) and then time the
kayak over a fixed distance at that maximum effort. Unfortunately, as soon
as I put out less effort than my maximum I have no way of knowing just how
much less I'm doing by feel. I recall one (very sharp and with a doctorate
degree as well) tester making a guess he was putting in 90% of maximum
effort to go a few tenths of a knot slower in a kayak he was testing over a
nautical mile. Horsepower curves I had generated for that boat and using the
paddler and boats weight in the calculations would have indicated that what
he subjectively had guesses to be 90% of maximum effort was likely less than
70% of the horsepower. Therefore, I think it is more necessary to get
objective data for drag comparisons at different speeds to back ones claims
of advantage in that realm where subjective impressions are notoriously
poor.

John proclaims (6) the data Sea Kayaker got for rudder drag at three knots
was flawed. While it may have been flawed, I don't know why that might be
(and I was watching what was done at the testing facility during the tests
run previously and also on the day before the rudder tests were run. I'd
like John to tell me how he knows that data is flawed. I've never claimed
that it applied to all rudders, but it was carefully measured in a facility
designed to make careful measurements of drag and it was repeated again with
the same result (for the same rudder/boat combination that was tested). The
repeat was done because Sea Kayaker's editor at the time, John Dowd (who was
there), was a big fan of rudders and didn't believe the initial result and
assumed there must be some mistake.

It is also very frustrating to have a long list of numbered points dismissed
for "specious logic". First, I'd like to hear the definition of specious
logic and then be told point by point why John considers it so in each case.
I'll be the first to admit that my best guess at why something seems to me
to be so could be wrong, but let us read why you think so, and what your
logic (specious or otherwise) is on the matter as well, point by point,
rather than by wholesale dismissal. You don't even let the reader (or in my
case the writer) easily know which points you are discussing (only the point
number that one might find by looking in past e-mails if one still has
them). I went back to see just what John was proclaiming were examples of
specious logic but I'd like to ask: How many other Paddlewise readers did
the same? 

I put considerable effort into trying to explain my thoughts on Paddlewise.
So often, what I get back from John are dismissals given as though by
proclamation. Or an appeal to obscure authorities he claims say differently
(but often won't even tell us what they say other than to tell us they agree
with him and they can be found in some obscure documents that you may need
to join and exclusive club to even find). These vague dismissals trouble me.
I think discussions and argument are a good thing if they help us understand
the world better in the end. Please show me point by point why I am wrong or
being illogical.

Matt Broze
www.marinerkayaks.com  
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