There is a pirate ship on Margate beach – although instead of a skull and crossbones, it is flying the flags of the four UK nations. Sunbathers are crowding round, taking pictures of the town’s unusual visitor. A hundred years ago, no one would have batted an eyelid. The boat, named Snark after the fictional animal in the Lewis Carroll poem, would have been one of a dozen such ships in the bay. It is not really a pirate ship, of course, but a swashbuckling Thames barge. These six-sail barges were once a common sight on the Kent coast and beyond, carrying cargo in and out of London. At the turn of the 20th century, there were more than 2,000. Today, there are only about 30 left. Snark isn’t one of the original barges, nor is it an historic replica. Although it was built to plans from 1898, and certainly looks the part, owners Paul and Xiao used modern materials and equipment, simplified the handling of the sails, and fitted out the main cargo hold with crew and guest cabins and a spacious, stylish galley (they are both architects). Since they completed the boat in 2018, it has been their home as well as their business. The couple have previously run retreats on Snark from their base near Dartmouth in Devon, but this year they’ve embarked on a new challenge: sailing around Britain. Although the boat is a whopping 32 metres long and weighs 67 tonnes, Thames barges are designed to be sailed by just two people – and Paul has 35 years of sailing under his belt. They are visiting the four capitals of Britain and other historic ports over a 10-leg, three-month journey, with different customers joining them for each stretch. I boarded ship in Eastbourne, East Sussex, at the start of stage two (their voyage started in Plymouth). Three guests joined for the first leg but I had the luxury of being the only passenger, with a snug cabin and my own bathroom. Snark can carry up to 12 passengers, but tends to take a maximum of six on longer trips. While their customers vary, the trips are especially popular with solo women over 50; some have sailing experience but none is necessary. Meals are cooked by Paul from fresh, local ingredients where possible, and eaten on board. On the first night, we had sea bass landed that morning, with vegetable pilaf, fennel and buttery samphire (the menu is pescatarian). Beer and wine is included, but in moderation, and BYOB is banned – Paul explained that drunkenness on boats is dangerous and can be deadly. After dinner, we turned in early; we had a 6am start in order to catch the flood tide. My cabin had a window, a desk and a bed. I found the gentle movement and creaks of the boat soothing, and slept soundly every night. The first day’s sail was the longest: about seven hours to Dover. Two seals popped up alongside us as we left the marina. I was worried about sea sickness, and the sea was a little choppy, especially near Dover, but the sheer size of Snark means it doesn’t bounce about too much, and Paul and Xiao don’t sail in rough weather. Passengers can pitch in with the sailing – Paul will show beginners the ropes – or just relax on deck. I favoured the latter option, with a cup of tea and a book borrowed from the ship’s library. We sailed close enough to the shore to see Hastings, Dungeness and Folkestone, before the white cliffs came into view. Dover isn’t the prettiest port – we were moored next to a dredger – but we had a delicious dinner (veggie noodles with fresh mackerel, homemade madeleines with raspberries and ice-cream) on deck, with a view of the castle and church. On day two, we had to navigate the 10-mile-long sandbanks at Goodwin Sands. We passed Deal and Ramsgate, timing our arrival into Margate at high tide. We dropped anchor and had a beer in the sunshine as the tide receded, leaving Snark resting on the sand. Then it was a simple case of shinning down a ladder on to the beach and walking to the Turner Contemporary, the vintage shops in the old town, and the pubs on the seafront and harbour arm. I returned to the boat before the tide came back in, and we ate crab salad and homemade pizzas as the sun set and the water started lapping around us once more. The next day, the wind was favourable and we were at full sail towards Whitstable. We had planned to eat out that night at a seafood restaurant. However, the harbourmaster denied us permission to enter. Whitstable is a busy working port and there was no berth for a big Thames barge, and too many oyster beds to find an anchorage. So we sailed on to the Isle of Sheppey, entering the Swale tidal channel and anchoring opposite the Ferry House Inn. Another Thames barge, Mirosa, was at anchor nearby. Paul and I went ashore on Boo, the tender, and settled for a pint of oyster stout instead of the oysters. On our return, we bumped into Peter, the owner of Mirosa, who told us his boat was built in 1892. He has owned it for 45 years. Its traditional black hull and red sails looked resplendent under a full moon. On the morning of my final day, I did a yoga class with Xiao (she is a qualified teacher), then we had a Chinese-style breakfast: rice with toppings including smoked haddock, wakame, mushrooms and pickled vegetables, plus baked eggs with soy sauce. We were heading to Chatham, where I would disembark and get the train back to London; Xiao and Paul were going to the Thames Match, a race for Thames barges dating back to 1863, in Gravesend first. Again, though, our plans had to change. The lifting bridge at Kingsferry, not far from the Medway, was closed due to the heat, so Snark couldn’t pass. After a quick rethink, Paul and I jumped back into Boo and headed up Milton Creek to Sittingbourne, where I could catch a train. We passed the sad sight of a wrecked Thames barge, left to rot. Then, more happily, we reached a boatyard that was restoring Raybel, a 1920s barge. These boats are part of Britain’s heritage, and worth preserving. And, as Snark shows, there is a place on the high seas for a modern “pirate ship”, too.