Only if the cruisers are significantly slower than the "race" fleet. In this case, your "cruising" fleet may be foilers...
And cruisers typically just take their own times (or should be required to post their track or photo of GPS showing time & coordinates. They're not getting trophies anyway...
This is really off the topic and if they are cruising but sailing with the racers, what's the point in doing a race other than possibly getting in the way. Please focus on ratings systems not cruising.
