Rich your Dauntless is fast approaching museum quality. Bravo!

On the subject of painting the hull, I'm not happy with my attempts at accurately establishing the water line. Masking the waterline for paint toward the bow was simple. But it starts getting tricky toward the bow as the hull takes a V shape. Short of floating it in a pool and marking it with a pencil, is there a simple, accurate way to know where the waterline should be?