A Thames sailing barge is a type of commercial sailing boat once common on the River Thames in London. The flat-bottomed barges, with a shallow draught and leeboards, were perfectly adapted to the Thames Estuary, with its shallow waters and narrow tributary rivers. The larger barges were seaworthy vessels, and were the largest sailing vessel to be handled by just two men. The average size was about 120 tons and they carried of canvas sail in six working sails. The mainsail was loose-footed and set up with a sprit, and was brailed to the mast when not needed. It is sheeted to a horse, as is the foresail; they require no attention when tacking. The foresail is often held back by the mate to help the vessel come about more swiftly.
The topsail was usually first sail on and last sail off, being fixed to the topmast by hoops. In the upper reaches of the rivers and constricted harbours it reached into the clear air, and when approaching a berth casting off the halliard would drop it immediately killing the forward drive. The mizzen boom in a mulie is sheeted down to the long shallow rudder. The masts are mounted in tabernacles so they can be lowered to pass under bridges; the anchor windlass is used to lower and raise the gear via triple blocks. This takes considerable effort and to aid in the process 'hufflers' were often used. They would come on board to help with lowering and raising the gear (for a fee). The bowsprit where fitted could be 'topped', helping where space was limited.
The river barges worked the London River and the Port of London. Cut barges were smaller so they could pass into the Regent's and Surrey canals. The larger estuary barges were seaworthy craft working the Kent and Essex coasts while coasters also traded much further afield, to the north of England, the South Coast, the Bristol Channel and to continental European ports. Cargoes varied enormously: bricks, cement, hay, rubbish, sand, coal, grain and gunpowder. Timber, bricks and hay were stacked on the deck, while cement and grain was carried loose in the hold. They could sail low in the water, even with their gunwales beneath the surface.
They sailed the Medway and Thames in a ponderous way for two hundred years; then in the 1860s a series of barge races were started, and the barges' design improved as vessels were built with better lines in order to win. The Thames barge races are the world's second oldest sailing competition, second to the America's Cup.
Build and rigging
The vast majority of barges were wooden hulled (although a significant number of later barges were also built in steel), between long with a beam of around . The hull form was as distinctive as their rig, being flat-bottomed with no external keel. There is a degree of flare to the sides and plumb ends. The stern was a transom, shaped like a section through a champagne glass, on which was hung a large rudder. The hull was mainly a hold with two small living areas in the bow and stern, and access was through two large hatchways, the smaller before the main mast and a much larger aperture behind. To prevent her unwanted (sideways) passage to the lee, are two massive pivoted leeboards.
They were usually spritsail rigged on two masts. Most had a topsail above the huge mainsail and a large foresail. The mizzen was a much smaller mast on which was set a single sail whose main purpose was to aid steering when tacking. The rig also allowed a relatively large sail area on the upper part of the mast, to catch wind when moored ships, buildings or trees blocked wind on the water's surface. The topsail could remain set even when the mainsail had been brailed to the mast. Sail areas varied from depending on the size of the barge. The typical, rusty-red colour of the flax sails was due to the dressing used to treat the sails that were permanently aloft (traditionally made from red ochre, cod oil, urine and seawater). The red ochre was there to block the ultra-violet in the sunlight from degrading the sails (much as lamp-black was used in the sail dressing for the Norfolk wherries), but sails that were stowed away such as jibsails were usually left untreated. The barges required no ballast, and sailing in this condition with leeboards raised they typically draw only 3 foot; this has caught out a few modern yachtsmen who have run aground while attempting to follow them. No auxiliary power was used originally but many barges were fitted with engines in later years and most retain them, but among the surviving sailing barges both Mirosa and Edme have never had engines.