World Sailing Official Case Book
Case 69
Momentum of a boat after her preparatory signal that is the result of being propelled by her engine before the signal does not break rule 42.1.
Facts
In a flat sea and 1-2 knots of wind a boat enters the starting area under power shortly before her preparatory signal at a speed of 5-6 knots. At the preparatory signal she is moving at the same speed but no longer motoring. At 2.5 minutes before her starting signal she hoists her sails and slows to 2 knots.
Question
Does she break rule 42.1?
Answer
No. A boat begins racing at her preparatory signal. During the period in which the boat was racing, she was using wind as a source of power as required by rule 42.1. Her motion also resulted from momentum created by engine power that propelled her before she began racing. Nothing in the rule requires that a boat be in any particular state of motion or non-motion when she begins racing. Therefore rule 42.1 was not broken.