Submerging Sensors How technology drives change, as well as big ships In this article we look at how technology is changing and improving performance of machines, in particular ground-breaking water jet propulsion technology. Subsea sensors need to be robust and reliable, as replacing or maintaining equipment that operates underwater is a time consuming and difficult job. Non-contact sensors are ideal for aquatic applications, as the presence of pollution and small marine creatures' means that contamination of sensor surfaces is inevitable. Submergible non-contact tilt position sensors from Positek can be used at depths of up to 3,500m, in any wet environment, whether that is at sea, in fresh water or in any other environment where non-corrosive liquids are present.Submarines and other subaquatic vehicles used for marine biology work and maintenance of underwater pipelines use all sorts of sensors, including tilt, linear and rotary sensors to facilitate remote operation of machinery and other robotic equipment, used for research and repair work. Sea-going vessels also use submersible position sensors for a variety of applications, including in ground-breaking water jet propulsion technology.Water jet propulsion is a sustainable method of powering vessels and offers excellent handling and manoeuvring capabilities, thanks to the high level of control that the operator has over the water jets. Hamilton Jet, a New Zealand based company, is leading the way with this technology, and recently supplied a system to the US military, for use on a 140 foot support vessel. The four water jets control the steering and driving capabilities of the ship, which can reach speeds of 28 knots. Ducts within the system, control the direction of the water flow to effect forwards and backwards movement, with full speed achievable in both directions. Water is also deflected laterally to allow steering in either direction, and the combination of the two allows for 360° steering.Hamilton Jet originally used potentiometers to measure the position of the ducts and lateral steering deflectors, but they did not last more than two weeks at a time, due to the vibration caused by the changing water flow, leading to wear and tear on the rest of the equipment. This arrangement was obviously not sustainable in the long term, so alternative sensors were needed.Dick Borrett, one of Hamilton Jet's Chief Engineers, contacted Positek about the P500 sensor, which is both waterproof and accurate enough to meet the 1mm requirements of the steering system. The P500 is a non-contact sensor which is available in a water and oil proof casing, making installation in water jet systems very simple, as no additional protective housing is needed. Not only was the P500 better in terms of performance and ease of installation than the potentiometers that had been used initially, it was also cheaper up front, offering savings on the initial cost, as well as in terms of ongoing maintenance and replacements.The accuracy of the P500 allows operators to finely control the ducts and deflectors, to achieve a high degree of control over the steering and thrust of the ship, which allows the vessel to hover in place. This is a vital capability for support vessels, as there is frequent loading and unloading of equipment, supplies and crew.Positek and Hamilton Jet are now working closely together, with thousands of units supplied to the water jet propulsion company since the initial contact. The performance and durability of the P500, as well as Positek's ability to custom build sensors for bigger and better waterjet systems, means that the working relationship is likely to continue for quite some time yet, and has also helped Hamilton Jet win more contracts for its pioneering technology. Article published on: 01/01/1900 Article last updated on: 01/01/1900