towfish

A towfish is a device deployed behind a surface vessel to tow various types of underwater survey equipment. Its primary function is to carry instruments such as side-scan sonar, sub-bottom profilers, or magnetometers at a controlled depth and distance from the towing vessel. This allows for efficient surveying of the seabed and near-seabed environment. The towfish is connected to the vessel by a cable, which provides power to the instruments, transmits data back to the surface, and allows for the manipulation of the towfish's depth and position.

The design of a towfish varies depending on the specific equipment it carries and the operational requirements. Common features include a hydrodynamic shape to ensure stable towing, ballast for controlled buoyancy, and mounting points for the towed instruments. Some towfish are equipped with active control systems that allow for precise depth and attitude adjustments. These systems can help avoid obstacles, maintain a consistent survey altitude, and optimize data acquisition. The cable connecting the towfish to the vessel is often armored to protect it from damage and may contain fiber optic lines for high-speed data transmission.

Towfish are essential tools in marine geophysics, hydrography, offshore engineering, and underwater archaeology. They enable the mapping of seafloor topography, the identification of underwater features such as shipwrecks and pipelines, and the assessment of geological structures beneath the seabed. The ability to tow instruments at a stable distance from the vessel is crucial for obtaining high-resolution and accurate survey data. The selection of a towfish and its configuration depends heavily on the project's objectives, the water depth, and the types of data being collected.