Halyard's insulation products use a multi-layer construction which offers the best possible acoustic result in a range of thicknesses which can be accommodated in the tightest engine space, beating simpler materials many times as thick. • Zero fire rated • Unique absorption layer • Choice of three levels of sound absorption • Choice of three different facings • Simple to install

Noise LossMarine diesels create very high noise levels – often well over 100 decibels. Engines are always located close to the boat user, generally in engine spaces made from GRP, timber or steel. Engine noise is then amplified by bouncing around between the hard bulkheads and the steel of the actual engines. Noise contributes seriously to fatigue and seasickness, as well as spoiling life on board.

Noise insulation changes all this. It adds a soft facing to hard bulkheads to absorb noise and stop it bouncing around and growing. It adds weight to the bulkhead to reduce noise transmission. It features a clever multi-layer construction to make a thin material more effective than simple insulations many times thicker.

If you cocoon the engine with noise insulation you can reduce airborne noise by 85% and transform the comfort for all on board. (Remember structure-borne noise and exhaust noise are separate subjects, covered elsewhere in this site: Halyard can help with both.)

Marine diesels are more of a problem than vehicle engines, because a marine engine shares the hull with you. The insulation you use, therefore, has to be much more effective. The key to HMI Noise Insulation lies in its multi-layer construction. Vehicle insulation is usually a fibre padding which absorbs some noise. HMI insulation has three layers in addition to a protective facing – each with important functions:

Multi-layer insulationThe absorption layer

A thick layer of fire zero rated foam which soaks up noise and stops it bouncing around the engine space.

The transmission layer

A high-density barrier provides the highest possible mass and gives the best noise reduction. The HMI damping layer weighs 5kg per square metre – more than the lead sheet used in older materials.

The isolation layer

This thin layer of foam has a crucial function: it acts like the gap in double glazing and stops the noise which hits the transmission layer being carried through to the bulkhead – just like the gap in double glazing.

The multi-layer construction used in HMI materials offers the best possible acoustic result in a range of thicknesses which can be accommodated in the tightest engine space, beating simpler materials many times as thick.

Further information on Halyard’s Noise Insulation products.