Penzance harbour is the home port of the Car and Passenger Ferry to the Scillies. There is only one ferry called the Scillionian – a very distinctive white vessel that moors up on the seaward Pier to the Penzance Wet Dock. If the ferry is in port you can usually see it accross the harbour from the Penzance Railway Station car park.
The outer harbour is tidal and dries out to mud so the wet dock is the place that Classic Sailing vessels will use to start or end your voyage, so if you head for the Penzance – Scilly Ferry on foot or follow the road signs for the Scillionian Ferry you will find the Wet Dock. Next door is the famous Penzance Swimming Lido with bright blue flags.
The Penzance Wet Dock has a lock gate that can only be entered 1.5 hrs before or after high water, and the entrance is exposed to Southerly or SE gales, so it is possible the skipper of your vessel may have to dock in the nearby fishing port of Newlyn.