Okay - so as far as I understand, Portsmouth Harbour in the sim has an 'electronic bar' or shallow at the entrance but it could be opened up in the future, and in any case if we can get large ships past this barrier they will float properly further in.
I did notice though that the electronic chart shows 3 meters or less once beyond 'The Point' (harbour entrance). If it helps VSTEP I found this chart online. it not only shows the channels (often 10 meters plus) and mudflats, but also the shape of the marinas etc.
I was there last week and took the Wightlink yellow catamaran which goes from the Rail station just north of the spinnaker tower to Ryde pier. Coming home later we went to Fishbourne to get the double ended VS car/ foot ferry and this docked just south of gunwharf. By the way that little horseshoe shaped dock must be deeper than this chart shows as the ferries are much the same as the Red Eagle - and also there are fishing boats plus fin-keel yachts in there.
It strikes me that it would not be too hard to offer a repaint of the Red Eagle as Wightlink, put a version of the three-master in as the Warrior (and maybe Victory too) and some marinas. that way we would get (for minimum effort) a splendid extra bit. Incidentally I would also like to see an extension to the area such that both east and west 'ends' of the Isle of Wight are sailable. It is a brilliant sim though and all credit to them.