The sloping horizon in the first pic is quite unsettling on the eye! Strikes me as more importatnt for that to be level than the shore in the foreground!
Yes, definitely straighten the horizon on the first image – it’s the first thing that jumps out at the viewer. Otherwise, a nice shot. Could be improved by taking earlier or later in the day – or by using a polarizing filter.
The second image is a nice conversion, but I find it a bit messy in the foreground. If you crop it from the bottom to just above the second boat (so losing the bottom two boats) I think it would work much better.