I imagine sky in neg is much closer to the IR black look. Not sure whether this wouldn't have been better on ordinary film. Somehow this seascape doesn't lend itself to that ghostly/ surreal look that enhances IR. I was looking at a Simon Marsden book in which he specialised on derelict castles. He is rated highly in IR circles and yet in my opinion even he failed on a couple. The scenes were just wrong for what he was trying to do.
I'm not it's IR which doesn't work, but more to do with Kodak HIE film (which simon Marsden uses). HIE has way too much grain, plus the lack of backing makes the excessive sea-side light bounce around too much. I'm itching to get my hands on the new Rollei/Maco IR820 film, I have high hopes for this, especially in medium format.