It's a familiar summer sight as it ferries sightseers to see the seals on the sandbanks off Hunstanton.

Now the Norfolk seaside resort's famous Wash Monster has a running mate – aka Wizzy the Whale.

Skipper William Searle, who converted a former US army troop transporter from the Vietnam War into a pleasure craft 12 years ago, has bought only the second working vessel of its kind in the country.

The 60ft amphibious LARC (Lighter Aluminium Resupply Craft), with its huge wheels and two 300HP V8 diesel engines, is ideal for navigating the shallow waters of The Wash, as well as the estuaries of south-east Asia.

'They reckon these cost the American military $1m each to build,' said Mr Searle, admiring the vessel's spartan but rust-free lines.

'She's a resupply cargo vessel which could carry 200 troops or you could drive a lorry right up the ramp on to them.

'There aren't many of them left because when they finished with them out there in Vietnam, they just sunk a lot of them rather than bring them back.'

Mr Searle bought the former landing craft for an undiscloseed sum from a fellow enthusiast up in Grimsby, from where it was carried by low-loader complete with police escort to Hunstanton on Thursday.

Over the weekend Mr Searle's staff began work on converting the 21-tonne craft, which will be christened Wizzy – an acronym for Willie and Lizzy, aka Mrs Searle.

'She'll be able to carry 12 passengers plus she'll be available if the offshore industry needs a landing craft or ferry,' he said. 'We're investing in the future.

'The Wash Monster's so popular we had to make a decision whether to go for another amphibious craft.'

Mr Searle said spare parts were a problem – especially tyres for the LARC's huge wheels, which cost upwards of �1,000 a time.

On land, Wizzy will be able to manage 15mph, while at sea her twin diesels will push her along at around half that, depending on the tide.

As well as holidaymakers, the Wash Monster has also become a draw for military vehicle enthusiasts from across the country, because it is believed to be the only operational LARC in the UK, the nearest being a vessel which works on a salmon farm in Ireland.

First built in the 1950s, LARCs were said to be the only vehicle in the US army which could perform a beach landing through surf.

They saw active service in the Vietnam war, where more than 600 of the 968 craft produced were scuttled after the Americans departed.

The US army's last amphibious transport company was disbanded in 2001.