Vessel #2 is the stand on vessel. When we are racing and we are vessel #2 we are watching out for vessel #1. If it is determined that they are not aware of the situation we will yell "STARBOARD". They will then do one of two things: 1. they will change course right away or 2. they will tell us to maintain our course, meaning that they are aware of the possibility of a collision and that they will take action to avoid such collision. That being said... even they opt for number two (telling us to maintain course) I, being at the helm, don't assume anything and will make sure that we can take action if we have to.
Obviously if they don't acknowledge us at all then we will take the neccessary action to avoid a collision. Heck its only a race. And I don't remember where our red flag is... oh well.