A paravane is an aquatic device that functions similarly to an underwater glider. It typically has fins that cause it to dive when dragged. Sometimes called a water kite, paravanes are normally tethered to a boat with a towing cable. They are regularly used as boat stabilizers, depth controllers, and research equipment. They are also used by fisherman and the by the military.
Paravanes can range in size from a few inches to as much as several feet. Regardless of size, paravanes ordinarily apply the same principle. As it moves across the water, its fins, commonly shaped like upside down wings, cut through the water at an angle. Instead of inducing lift, the fins sink the paravane to a specified depth. It can then either operate independently or be controlled by a steering mechanism.
Paravanes are often installed on boats with full displacement hulls, to reduce the rolling brought about by wind and waves. Paravane stabilizers contribute to a smoother ride and are normally rigged on both sides of the ship, for an even roll control.
Passenger and commercial ships that do not necessarily travel at high speed often use paravanes. Installing paravanes on a high speed vessel is not recommended because the added weight and water resistance from the device is known to increase drag. This can considerably slow down the ship and affect its maneuverability.
Paravanes were developed by the US military to be minesweepers. The torpedo-shaped minesweeper is attached to a towing cable and dragged adjacent to the ship, forming a perpendicular towing line. Mines are neutralized when the towing line cuts the mine’s mooring cable. The mine then floats to the surface and is detonated.
In some cases, a paravane is used as a weapon against submarines by filling the paravane with explosives. These are usually deployed from a destroyer or an airplane to guard against retaliation. The explosives are detonated when a submarine comes into contact with the device or its towing cable.
Sport fishermen use paravanes as a substitute for lure weights. They allow the bait to sink to a specific depth while the lure moves, which helps in catching fish that are in deep water. The paravane can be attached between the line and the bait or can function as the lure itself. A metal version called a planar is sometimes used for its capacity to dive deeper.
A weight on the front end of the paravane lure causes the tip to point down. This causes the lure to travel downwards when it is pulled. When a fish tugs on the lure, the weight flips the paravane, changing its orientation. As a result, the lure rises to the surface, making fish retrieval easier.