Less noise and vibration is good for the working environment
High levels of noise can ruin your hearing if you are exposed to it for a long time. Constant low level noise and vibration can also have a major impact on your working life because it means poorer quality sleep, lack of rest and stress.
High levels of noise can ruin your hearing if you are exposed to it for a long time. Constant low level noise and vibration can also have a major impact on your working life because it means poorer quality sleep, lack of rest and stress. For example, if a fire door bangs or the hinges creak every time it is opened and your cabin is right alongside, it affects your periods of rest.
Noise and vibration require special attention on a ship because the crew are on board every day around the clock and are surrounded by noisy machinery and metal which transmits noise well. There are mandatory requirements for noise reduction on ships, and Danish flagged vessels have to comply with maximum limits for individuals (EU legislation) and special values for different locations in the ship (International Maritime Organisation legislation). This is to protect crew from long-term work-related impacts that in the worst case can lead to reduced ability to work and poor health.
On a ship, crew are to a greater or lesser extent exposed to vibration and noise practically all the time. The ship is their workplace and unlike workplaces ashore, they cannot leave the ship and have peace and quiet at night without noise and vibration.
This is why it is extra important for shipowners to prevent noise and vibration. Ships are made of steel and so there will always be noise and vibration on board so noise reduction is essential. Noise reduction is good but noise prevention is even better.
In this article, we meet a Danish shipowner, ESVAGT. In their latest newbuilding, they significantly reduced noise already in the design phase of the ship.
ESVAGT AURORA – effective prevention
Built in August 2012, the ESVAGT AURORA is Danish shipowner ESVAGT’s (www.esvagt.com) newest vessel. She has a special bow designed by Ulstein Design & Solutions, Norway, and was built by Zamakona Shipyard in Bilbao (Spain). She is specially designed for sea rescue operations in hard weather conditions and is on 24/7 stand-by by drilling rigs, typically in Arctic waters.
The most important reason for preventing noise on the ESVAGT AURORA was to reduce the impact of noise and vibration on the crew’s working environment. ESVAGT decided to reduce noise and vibration, by especially minimising structural noise. ESVAGT wanted to build as good a ship as possible which would also be a really good workplace for their shipmates at sea. A good workplace is a reflection of many things but one of the most important is a good working environment. That is why already in the design stage, ESVAGT focused on noise and vibration and maintained this focus throughout the whole construction phase until the ship was completed.
ESVAGT made a conscious choice to do something extra for the working environment. They identified and calculated potential sources of noise in the design stage with experts from the classification company DNV and designers from Ulstein Design & Solutions and on the basis
of being Danish flagged and the higher legislative requirements this entails, the level of noise and vibration on the ESVAGT AURORA was reduced by:
- Extra special insulation on all steel cladding, bulkheads and decking associated with the bow and retractable azimuth thrusters in the bow
- Extra special insulation in the accommodation and steel cladding on all decks
- Noise absorbent flooring solutions arranged as special cassettes consisting of ‘boxes’ of noise-absorbent material covered by a flexible compound layer
- Large diameter propellers for the propulsion azimuth thrusters to minimize propeller noise
- Bow and retractable azimuth thrusters fitted with converters and adjustable pitch to make it possible to adjust pitch and revolutions simultaneously. The reduction in revolutions has a major significance for noise from these units
- Special shock absorbers installed under all diesel engines to minimize noise and vibration
- Rubber suspension exhaust systems fitted with noise reducers
The results have been good. The noise is minimal and reports from seagoing crew say: “One of the best ships in the fleet to serve on.”
The full article by Carsten Gydahl-Jensen, on the impacts of noise and vibration, effective prevention and risk assessments can be downloaded from: https://www.nautinst.org/resources-page/he-alert-habitability.html