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Sound evaluation and control for recreational marine craft (SOUNDBOAT)

Deliverables

SoundBuoy is a free- floating device equipped with a differential GPS navigation system and a type I sound level meter. The buoy is linked via radio to a tablet PC on the boat being tested to which it transmits its position and sound level. On the test boat, the SoundBuoy computer instructs the skipper to steer towards a point 25m from the buoy in accordance with the ISO standard. All instructions are given verbally via a small "Bluetooth" earpiece so the skipper can always look ahead and concentrate on the safety of the boat. Once sufficient data has been gathered, the SoundBuoy system stores the information in an encrypted file, which is then e -mailed to the notified body for certification. Alternatively, the buoy can simply be used for routine engineering tests, in which case there is no encryption and reports can be printed off directly. SoundBuoy is launched and recovered from the test boat and can be used in any depth of water. For transportation, it breaks down into components of no more than 1m in length. This new system does not require a support boat and crew, and entails no mooring or anchoring. The test boat can approach the buoy from any direction allowing much greater flexibility, control and safety.
SoundBoom is a physical device, which allows a prediction to be made of a vessel's pass by sound levels from simple measurements taken on board. The boom consists of an extending pole with a microphone and wind- shield fitted at one end. Withn the handle of the boom itself is a power supply and amplifier, which is connected to a lap top computer via a USB link. Five sound measurements are taken at predetermined positions on the boat and these are analysed in real time by the lap top computer. On completion of the fifth measurement the predicted 25m pass-by sound level is given. Analysis of the on board sound levels is carried out using a predictive algorithm which is one of the main outputs from the project. The algorithm is in two parts: the first provides a prediction of the water noise and the second is an empirical method for exhaust noise derived from the data collected during the project. The overall level of uncertainty has been set at 3dB and the method is not yet accepted for certification.