We have been getting an annoyingly large amount of spam on the forums lately. I believe I may have partially solved the problem - All spam is posted by 'spambots' - not actual people. In the 'UK Ferry Discussion' board, it seemed that guests had the ability to start posts there - all spam we have received has been in that board. I have disabled the ability for guests to start posts. Spam will be further reduced by the forums software being upgraded (InvisionFree is upgrading their software).
I hope this explains it.
Regards, and Merry Christmas.
Julian