This:~
http://www.redfunnel.co.uk/
is the website of the Red Funnel Ferry Company.
Their fares (both for foot passengers,and car) are MUCH cheaper than the othe Ferries to IOW.
This is because they sail out of Southampton and NOT Portsmouth.
Their journey time is longer because they sail down the Solent to East Cowes.
I tried a foot passenger day return for Mon 20th July and (leaving at 9am returning 6 pm) it was �14.00 round trip.I think this is considerably less than the other Ferry Companies,BUT,I haven't looked at their sites.