Switched-on communities are helping to reduce marine theft which can ruin holidays and cost boat-owners thousands of pounds.

Thieves steal outboard motors from boats moored along the north Norfolk coast, south Norfolk, the Broads and around Downham Market. They also target boatyards, sheds and back gardens.

And despite a drop in incidents of marine theft it remains a problem, according to PC Jason Pegden, beat manager of Wells Safer Neighbourhood Team.

Between January 1 2010 and January 1 this year there were 165 marine property thefts.

Mr Pegden said: 'We get a few people arrested each year but not many. The offenders are usually people from out of the county and it is a very difficult thing to police - it's one of those annoying things that can happen late at night. But people are becoming more switched on about it.'

Hotspots for marine thefts are in Morston Quay, Blakeney Point, Brancaster, Wells, Langley Dyke and Hardley Dyke near Loddon, Brundall, Martham, St Olaves near Great Yarmouth, Hickling and Wroxham.

Mr Pegden, who regularly patrols the water from Cley to Holkham, said the problem peaked around five years ago.

Following that period, a trial at Wells to remove the tops of the engines and cover them with PVC covers was such a success it spread across Norfolk and boatyards across Britain.

Smaller engines can cost between £700 and £2,000 and larger engines cost between £2,000 and £16,000.

Neil Thompson, secretary of Blakeney Harbour Boatman's Association and owner of Neil Thompson Boats in Glandford, said not one of the boats fitted with a cover at Morston has been targeted by thieves.

Mr Thompson said: 'A lot of the boat owners are people who holiday in Norfolk so when they turn up for one week of sailing and their engine is missing it can ruin their holiday. It is organised crime, not opportunists hoping to get a few quid.'

He said the level of this type of crime was reducing but it remained a worry and a threat for boat owners.

Officers are encouraging people to join a boat owners' database as well as running a boat marking scheme.

The covers come in three sizes and cost between £28 and £34. They can be bought from Wells and Hoveton police stations. For security advice and to report anything suspicious call 101.