of several regattas and six extant clubs (see below). A large version with a canvas is called a camping skiff, featuring in major modern travelogues and historically in Three Men in a Boat, published in 1889, a humorous account by English writer Jerome K. Jerome of a two-week boating holiday on this river from Kingston upon Thames to Oxford and back to Kingston. Other rowing typically takes place in dragon boats, dongolas, dinghies, inflatable rafts and larger skiffs known as cutters. Regattas Thames rowing regattas are almost all between April and the first week of September. All but the most prestigious are considered short. They are raced side-by-side. They are in categories for competitors and boat types: each consists of heats (mostly knock-out tournaments, that is, without repechages) and final. Many regatta days are split into two or more divisions so that competitors can enter two categories – such as a large and small boat, sweep-oar or sculling. Where category events have a cup it belongs to the regatta and is sometimes engraved with winners' club or composite clubs' name (or engraved on metal set around a plinth or set of plinths). Winners receive a medal – or tankard, called by rowers a "pot". A regatta in racing shell rowing has umpires/stewards who enforce preparedness (race registration, safety and marshalling time/location rules), false start and lane rules using a motor launch and the wearing of club kit. "General" refers to a mix of skiffing, cutters, dinghies and other rowed craft. Head of the River and long-distance events Head of the River races (Heads) and other long-distance events dominate the winter months, and are usually processional (time trials): competitors set off at time intervals, and results are on the basis of comparative timing or by bumping (catching up the boat in front). Many of them on the Tideway are raced over The Championship Course, and apart from the Boat Race and Wingfield Sculls, may begin from Mortlake (west) or Putney (east) whichever tide matches the middle of the day or other central racing hours. Other events The Boat Race Women's Boat Race Henley Boat Races Doggett's Coat and Badge Great River Race Clubs Rowing on the river is generally organised through clubs based on the Thames, which include the following. Competing many times per year Universities Imperial College Boat Club Imperial College School of Medicine Boat Club Kingston Student Rowing Club