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Try flying when its getting dark, see how its almost black though?
Well there's your problem. You are in a Spit, not a F4U. Spits love the water, while F4Us and their hover flaps are hydrophobic.
I've found that I have problems too with gauging the distance, but my solution is to fly planes that I know to the nth degree if I'm going to be flying out over water. That way, I know how far to pull the stick to get my desired result, and when trying to turn with that Spit16 OTD at 300ish with two notches of flaps, I know I won't pull into a snap roll. (Doh!)