(no subject)

PeterO wrote,> A couple of us were wondering if fixing the rudder in this
"dead ahead" > manner would increase the hull's limiting speed, or whether
it's >really > the cockpit to bow length that tends to govern a kayak's hull
speed? In > other words would removing the rudder slow the boat down >on a
calm water > surface with negligible wind or current.While I agree with John
Winters that the kayaks hull speed would not be effected much with the rudder
removed (and I'm somewhat familiar with the Mirage) there could be a small
speed advantage to fixing the rudder straight back instead. The stiffer
tracking would slightly reduce the amount of the paddler's energy going into
moving the kayak side to side. Removing the rudder might also create another
problem. Because the Mirage has a shaped rudder that is blended into the stern
shape with the rudder missing that might create some additional separation
drag from the stern profile with the rudder removed completely that would
outweigh the friction savings from removing the rudder. If the stern profile
sans rudder is sharp edged and allows a clean separation of the water from the
hull (and it still tracks pretty stiffly without the rudder) it might even be
faster. This is one reason why powerboats that plane have a transom stern with
a relatively sharp corner below the waterline. John Winters wrote: "At this
speed wavemaking resistance may be at its maximum but one can usually go much
faster". I think that, for most hulls anyway, wave making resistance isn't at
its maximum at hull speed. At best the rate of increase in wave drag (and
total drag) may be at its maximum near hull speed but both frictional and wave
drag keep increasing well beyond "hull speed". With long narrow hulls, this
rate of increase in wave drag tapers off some at faster speeds so that "hull
speed" isn't fixed a limit to top speed. However, you are going to have to be
putting out a maximal effort in trying to climb out of that hole you made in
the water (essentially hull speed is when you start working against gravity as
well as friction) and unless you added effective hydrofoils or an additional
source of power, like an engine or motor, you are not going to go a whole lot
faster than "hull speed" for very long.
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