fog horns, rotating radar antennae etc. Some of the more sophisticated powered racing boats may also have additional remote-controlled functions. These may include remote mixture control allowing the driver to optimise the fuel/air mixture during a race. Another function occasionally implemented for racing boats using a surface piercing propeller is remote control of depth or angle of thrust. There are three main types of power boat. RTR(ready-to-run), ARTR(almost-ready-to-run), and kit versions are available. All thoroughbred racing boats are made from kits and the builders add their own gear and radio. Radio-controlled racing boats are designed for maximum speed and maneuverability. Various styles of racing include circuits of different shapes laid out on the water with buoys. The most common courses are the 1/6-mile oval that consists of 330-foot straight sections followed by 70-foot-diameter turns. The International Model Power Boat Association (IMPBA), North American Model Boat Association (NAMBA) and Offshore Model Racing Association (OMRA) have specific rules and regulations to address the course, race rules, and formats. In addition to oval racing there are straightaway (SAW) racing. This is a contest to see how fast you can make the boat go in a straight line. Timed events are held where the boats need to go through a starting light and an ending light. The speed is calculated by the timed difference from start to stop vs the length between the lights. Again IMPBA and NAMBA rules apply. Some enthusiasts race in the sea, controlling their craft from a pursuing boat known as a "chase boat". These courses will usually be a few miles long and the competition is judged against the clock to find the fastest in class. Within the various styles of racing there will be a number of classes depending upon engine size and type. Ocean and river going boats tend to be powered by internal combustion engines. Sprint Type races and electric races are usually held on calmer lake waters. Electric boats for racing are capable of reaching speeds of more than 50 mph and run times of around 10 minutes. Electric boats also hold the 100-yard sprint record against rival internal combustion powerplants since 2000. Tethered racing and free-running craft were popular prior to the advent of cheap radio control. The speeds of tethered racing vehicles are higher than 160 mph for boats and 230 mph for cars, but these craft bear little resemblance to real-world vehicles,