I’m wondering if a storm cover on its own, without hood or tonneau, would keep the rain out?
It depends on the quality of the storm cover. I have had one that would barley keep a light drizzle out.
My John Taylor cockpit cover keeps out all the water. The one that covers the louvres proects the engine against water but can cause "patiation" where the edging touches the bonne - especially if it is windy. Swings and roundabouts.
