The bridge over Britain's shortest canal

This morning I headed back to Peterhead harbour, always a source of something interesting.
Originally, there were two harbours, north and south, which operated separately until 1826, when Robert Stevenson suggested connecting the two. His son David drew up the plans for what was to become the shortest canal in the UK at just 15 metres in length!
 Access for traffic across the canal is provided for by a rolling lift bridge. Known locally as the Queenie Bridge it was being raised as I arrived to allow the passage of the Flying Scud, a tug/workboat operated by the Peterhead Harbour Authority.