I'm sort of looking at 290's and, 270's, one of my big concerns is the lack of access because of the center hatch. From reading these posts, I think I understand how it works now, but please correct me if I'm wrong. There is a center hatch for casual maintenance? Then there are two hatches directly over the engines,for major maintenance which are part of the seating system? Is this hatch screwed down? Is said hatch over the engines water proof without sealant? I have been on a 270 XF, but it has outboards.