from the fowey harbour website :
Water Taxi
A privately operated Water Taxi operates from 0700-2330 hrs, weather permitting from May to September. These brightly yellow coloured craft operate on VHF channel 6 and will take visiting craft crews from boats to and from various shore points . Telephone 07774 906730 Website http://www.foweywatertaxi.co.uk/
edit - it appears the water taxi website isn't live yet. if you don't believe the harbour site info it'll be a phone call.
there is lots of dinghy space for going ashore both at victoria steps by the harbour office and on the inside of the lifeboat mooring pontoon slightly higher up river.
Just spoken to the water taxi man on 07774 906730. He is now running Sat and Sun only, until about 10:00pm and finishes on Sun 22nd. All this is subject to the weather.