From cabin to cabin highly sensitive measuring instruments have been used to assess noise and vibration levels at various engine speeds.
J & A Enterprises, VSY consultant, carried out noise and vibration measurements which confirm that what VSY’s engineering team designed – not only works but goes beyond expectations. At a speed of 15 knots and the engine at 1480 rpm, with air-conditioning plant and stabilizers in function, measurements gave a noise level of 40.7 dBA in the owner and guests’ cabins.
This value reduced to 25 dBA with the stabilizers and air-conditioning turned off . Impressed by these values, Darrell Milburn stated that the noise reduction achieved on the Stella Maris was the greatest he had yet experienced in this category. The Report states: “Underway at 15 knots was 8 dBA quieter than the requirement in the Main Lounge forward area. While underway, the low frequency bands below 160Hz were increased, related to the main engines and propulsion machinery. The third octave levels in these bands were significantly quieter than found in many other 70-75m motor yachts. The noise reductions in comparison to other yachts are related to the effectiveness of the main engine/reduction gear isolation system, the silencing and isolation of the main engine exhausts, the effectiveness of the floated floor system, and especially to the highly damped effectiveness of the Main Salon side windows. The underway sound levels achieved in the Main Salon above the engine room are possibly a new benchmark for quiet noise levels in this location amongst motor yachts of similar size and installed power.”