Near enough, but you do get away with a small coaming on a large model with plenty of freeboard. A small model or one with low freeboard benefits from a taller coaming if one can be fitted. If it impinges on a window, it needs to be clear, at least in the window area. It should also go without saying that the coaming, to be effective, has to be continuous all round the hole, otherwise its just a handy way to discourage the superstructure from being blown sideways.