William R. Watt ) writes:
"Michael Daly" ) writes:
On 28-May-2004, (William R. Watt) wrote:

at sustained (cruising) paddling speeds hull resistance is still the
biggest component of total hull drag when comparing identical boats. there
are some numbers in a file on my website under "Boats" on average hull,
wind, and wave resistance, and energy consumption. a paddler can't put out
the power needed to maintain high wave making resistance speeds for any
length of time.

Nowhere on your website could I find info to support this.

look under Boats, Paddling, first item (Speed, Resistance, Energy).
I'd appreciate seeing more specific data.


An average person can sustain 1/20 horsepower. When a canoe or
kayak is powered by 1/20 hp in a dead calm the power is overcomimg
4 pounds of hull friction resistance and 0.05 pounds of hull wave
making resistance. If 10% of the friction resistance is due to
scratches, that's 0.4 lb compared to the 0.05 lb wave making
resistance.

Mike wrote he thinks the friction and wave making resistance would
be equal. For that to happen the paddler would have to be
sustaining 1/5 horsepower, or 4 times as much. The boat would be
going almost twice as fast. Athletes can do that. In short bursts
athletes can produce 1/2 hp.

In "Sea Kayaking" J Dowd's data assumes the paddler sustains 0.03
hp. The discrepency likely is due to a different boat being used
at the same speed. In a 10 knot headwind the wind and resulting
waves are producing 0.01 hp.

If hull scratches increase friction resistance by 10%, the paddler
has to produce 10% more hp to overcome it and keep the boat moving
at the same speed in a dead calm. In a 10 knot headwind the
extra power drops to about 7% of the total paddler output.
More precise data than what I have available could affect the
result.


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