That ship is the gunboat "Buffel" has been there for quite some time, it's part of the maritime museum, and does not sail anymore.
More info here (http://www.maritiemmuseum.nl/website/index.cfm?fuseaction=site.show&CTX_ID=217B8ACB110984F00A7C69CD8DDC1E29&CNT_ID=21E81887110984F00A3D2E0EC5ABF8D9)
And the white obstruction underneath her position on that google earth shot is actually just a removable walkway, so if needed they could get her out through the channel directly below her, on the photo.
Fred