Mmm, time to fire an email to my instructor... Thanks.
Okay, I did fire an email to him and he replied. Here is his opinion (Note that he is instructor at national level, with a lot of experience).
A very interesting point. However I’m not sure I agree that the rule precludes what I've suggested, “putting one foot in the water to increase drag and slow down".
Looking at the rule, clause by clause.
1 “a boat shall compete by using only the wind and water to increase, maintain or decrease her speed”
That’s OK, we’re using water
2 “Her crew may adjust the trim of sails and hull, and perform other acts of seamanship”
Not very seaman like but otherwise OK
3 “but shall not otherwise move their bodies to propel the boat”
We’re not propelling it.
So as I see it, if we use our hands to paddle forward, that’s illegal, but using hand (or leg) to slow down isn’t.
I guess that's one of those open to interpretation things...
