We are planning to take the 0915 passenger catamaran from Portsmouth Harbour, accessed at the back of Portsmouth Harbour railway station to the Island. This goes to Ryde Pier where we pick up the train to Shanklin. Taking the 0915 cat will get us to Shanklin and the start of the walk for 1015. The walk over St Boniface Down to Ventnor will take just under two hours and we are planning to have lunch at the Spyglass Inn on the seafront at Ventnor.
The time of the ferry from Portsmouth does not offer a good connection from Botley station which on a Sunday will have plenty of room for parking. However, there are good connections from Fareham station which make the rail option on this side also feasible. For those driving directly to Portsmouth, there is plenty of parking near to the ferry, with several car parks just a 100 yards or so from the station.
Links:
Ferry
http://www.wightlink.co.uk/ferry-travel-info/routes-destinations/portsmouth-ryde-catamaran/timetable
Spyglass Inn
National Rail
http://www.nationalrail.co.uk/