This question came from Simon:
I have become curious about the impact of speed on an English Channel swim. At present
I am doing 1 to 2 miles a day in the pool at around 2.1mph (yes, I time myself each swim to make sure I am improving!).
After just 5 months of training I have already improved my times and I
am sure I will improve still further but my question is how important
is speed to a crossing? I recall Michael Oram saying that so
long as you keep plodding away you will get there (I can plod away for
hours) but how much does this add to the difficulty? I am not just
thinking of the extra time spent in the water but more the tidal
switch and whether there is a minimum speed to avoid getting stuck
out there for an extra 6 hours when the tide switches.
My reply to Simon:
All of us who are training for a Channel swim hope to reach France in the least time possible. As you say, if you can avoid getting caught in a tidal shift, you decrease your chances of getting stuck – swimming in place for hours — with the coast of France seemingly within easy reach . . . but making no headway . . . because the tide has turned against you . So improving your speed certainly improves your chances.
The most important question to ask yourself is what is your plan or strategy to improve your pace? Timing your swims gives you information on your speed, but does it improve it?
Here are some things to think about with regards to speed (I prefer the term “pace” since speed makes us think of velocity, which means little to those of us who can’t think in terms of a sub-10 hr swim.)
1. To move forward in the water, the propulsive force you generate must exceed to resistive force of the water. To move forwardfaster you need to increase the difference between propulsive and resistive forces. Which takes more effort – increasing propulsive force or decreasing resistive? When you need to maintain your pace for 10-12-14 hours, you need to be very conscious of the energy cost of your intended pace.
2. I’d guess that the average Stroke Rate for Channel swimmers is around 60 spm. How long it takes you to cross will be purely a factor of how far you travel on each of those strokes. If you travel half a meter per stroke, it’ll take you about 76,000 strokes to cross. At 60 spm, 3600/hr it’s a 21 hr crossing. At .6m/stroke it’s 17.5 hrs. At .7m/stroke it’s 15 hrs. Etc.
This is why I previously suggested stroke counting in training is helpful. Suppose I take 40 SPL in the 50m pool. Subtracting 6m for the pushoff, that means I’m traveling 1.1 m/stroke the rest of the way. I KNOW I won’t travel that far in the Channel, but I figure it’s better to create muscle memory for 1.1m/stroke than for .9 m/stroke during those times I can measure my SL.
At this point I’m swimming 11x/week, 7-8 sessions in the pool and 3-4 in OW. I figure that 90% or more of the factors that will influence my pace are developed in the pool.