42.1 Basic Rule
Except when permitted in rule 42.3 or 45, a boat shall compete by
using ONLY THE WIND AND WATER TO INCREASE, MAINTAIN, OR DECREASE her
speed. Her crew may adjust the trim of sails and hull, and perform
other acts of seamanship, but shall not otherwise move their bodies to
propel the boat.
I guess using the water could be thought to mean putting your legs in the water to slow you down (BTW, I thought slowing down at any point is a bad thing, right?). However, a motor is "using the water" as well and they are certainly against the rules.
