When I raced Lark dinghies as a student we used to have illegal propulsion races on calm days. All manner of rocking, sail flapping, tiller waggling, etc but no paddles allowed.
How did it go then? If the northern Solent was anything like the western end there was a nasty bone chilling breeze coming from the northish. Still, as race officer you'd have kept warm by waving your arms about, broadcasting interminable race information and generally behaving like some kind of old fart.
Went out on bike on morning and not a breath of wind, at 11:30 there was a F3ish but bluidy cold .. so good racing but glad I was stomping about fleece clad.
hum. We had a sort-of unofficial race between four sailing boats with flat calm, so i went on the radio 72 or 77 whatever to say that all race participants can use engines. The airwaves promptly went bonkers with lots of others saying "Harump that does NOT apply to members of xyz sailing club!"