Click on the username of the person you are sending to. In this case PickledPig at top left of his post. This takes you to a new screen. Scroll down and at bottom left, there is a link 'Send a private message'
If you want to keep a copy of sent PM's you need to click the little box to save before you hit the send button
You can also send and read pm's from User options at top left of forum pages.
If round the cans racing is your scene, try contacting Liverpool Yacht Club. They run racing all year round and the Autumn and Winter series are the most competitive and best attended. People will definitely be looking for crew.