I've been thinking about this lately.  You see, I'm becoming a runner.  Never been before but I think you'd have to say that I'm getting there.  Which brings me to this point.  I think my "hull speed" is a 9 minute mile.

For those of you not familiar with "hull speed" it refers to a boats natural "max-speed".  Essentially the point at which you have to begin expending vastly more energy into the boat to get incremental speed increases.  For our family's Cal 40 sailboat that is approximately 6+ knots (6.5 maybe).

For me and running it appears that the 9 minute mile is about where my body likes to be.  Check out this chart.

Of course I have a chart, I'm a geek aren't I?

Anyways, the first datapoint is from February 6th.  Just coming off the long winters break and I walked half my route.  But look at the way the curve is settling down very nicely right at the 9 minute mile mark.

My goal of course is to get it much lower than that, but I anticipate having to expend a lot more energy to get there...and the energy is being expended vastly right now...at least that is the subjective opinion on the ground.

For those of you interested in this chart, go here: running log