Maritime Mystery

My colleagues got fed up with my coughing so sent me home. I'm not complaining. Miserable day and I can catch up with the backlog of SOA episodes I have recorded. I've watched one and think I'll have a nap now, but before I nod off, here is a small jetty I stopped at on my way home. I have no idea what the curved supports are, but there seems to be a pully system so maybe it's for launching small craft?