In an emergency call 999 and ask for the Coastguard

Whitstable Lifeboat was launched at 9.37 pm on Monday following a report of a red flare seen by an informant at Warden Bay on the Isle of Sheppey and appearing to be in the direction of Harty Ferry on The Swale.
Using a searchlight, night sight and radar the lifeboat crew conducted a search of the area from the entrance to The Swale and the various moorings off Faversham and Oare Creeks. The Herne Bay Coastguard Rescue Team also searched the area at Harty Ferry.
After nearly an hour nothing was found and the UK Coastguard released the lifeboat to return to station. The call was deemed a false alarm with good intent. Weather conditions at the time were northerly force 5 winds. This was the 56th call of the year for Whitstable’s volunteer lifeboat crews.