A security boom is to be laid as a trial in Portsmouth Harbour from today until Thursday (August 19) off Victory Jetty.

The trial is designed to identify and demarcate for all harbour users the 50m exclusion zone in force around Naval Base berths and specifically warships alongside – on this occasion, HMS Invincible at Victory Jetty.

The boom is expected to be deployed up to 100m off the jetty and running parallel to it, with buoys at either end in the form of yellow conical 96 litre floats, with a light fitted at each end and the centre for recognition in the dark.

The total length of the boom will be around 200m, with high-visibility pellets at 5m intervals.

In a Local Notice to Mariners (no 37/04), the Queen’s Harbour Master warns that “extreme care is to be taken in approaching this boom,” adding that Harbour Control should be informed of any immediate concerns.”