A hydrocopter is an amphibious propeller-driven catamaran with a boat-like hull, small wheels and pontoon skis (as in a seaplane). An aircraft engine with a propeller and air rudder powers the vehicle over water, ice, snow and land. Hydrocopters are used in Arctic coastal regions, primarily Sweden and Finland, during "menföre" (Swedish, bad going), or "kelirikko" (Finnish broken going) (see also Russian “rasputitsa"), when melting ice cannot support ground vehicles and boats are hindered as well. Hydrocopters are often used as a low-cost alternative to hovercraft and helicopters. Hydrocopters are primarily produced in small machine shops or made by hobbyists as hydrocopters have never been mass produced. Design and manufacturing Hydrocopters are generally smaller vehicles less than 20 ft long and weigh less than 2000 kg. Hydrocopters are powered by a fixed bladed aircraft propeller, the same as an airboat. Although they have the same propulsion as airboats, they are typically much slower. They typically travel under 12 knots whereas airboats are typically traveling over 40 knots. Hydrocopters use either skis or wheels on their pontoons to be able to travel on ice, snow or land in addition to traveling on water. This allows them to travel over terrain similar to a hovercraft. Hydrocopters use one system for lift and forward momentum while a hovercraft uses two systems, one for lift and another for forward momentum. Hovercraft have a constant down thrust which can be undesirable in certain conditions. Hydrocopters are also much cheaper than hovercraft. Hydrocopters have never been mass produced; they are made in small machine shops for individual customers. Consequently, they are easy to customize and there is a small but strong market for them. One of the first hydrocopters that was patented was called the Spider Craft. It is a small two-seater pontooned airboat and was patented in 1965. Since that time, hydrocopters have gone through multiple iterations. The current iteration is a modular design with steering and propulsion in the stern and the main cabin is in the first segment. This two-section design allows for faster turning and gives the occupants more space. Hydrocopters tend to use heavier fuel oil than airboats and airplanes. Additives are added to the fuel oil to avoid problems of freezing temperatures. Modern hydrocopters are primarily made from vacuum injected composites with a coating to prevent damage from moisture and cold temperatures. Hydrocopters used to be made much like airplanes