Ultraflex Group

Ultraflex Group HALYARD® Silencing and exhaust systems

HALYARD® - Silencing and exhaust systems

A marine engine exhaust system ejects the cooling water as well as silencing the engine’s combustion noise and removing the exhaust
gasses. The system must create minimal restriction to the flow of exhaust gasses, known as back pressure, or the engine may be damaged.
Halyard® produces GRP silencers using specialist resins, allowing Halyard® silencers to survive remarkably high temperatures if the cooling water supply blocks for short periods. Halyard® silencers are usually made from filament wound GRP tube, manufactured in our own plant, which is hand-laminated with flat sheet bases. Every single silencer produced is pressure tested individually to guard against leaks.
GRP is used as the base material to avoid the corrosion and acoustic problems of welded stainless units, and to avoid the low melting points of plastic silencers. Although normal marine exhausts run at between 40°C and 60°C, Halyard® silencers will remain operational after exposure to 300°C or more, while a plastic unit will melt at around 150°C. Halyard® GRP silencers are approved by Lloyds Register.


Here are four main objectives achieved by Halayard®:
1. To reduce noise by between 40% and 90%.
2. To cool the exhaust, and eject the engine cooling water through the exhaust without excessive back pressure.
3. To minimise the risk of water running back up the exhaust and into the engine cylinders, causing serious engine damage.
4. To site the outlets at the stern of the boat to minimise exhaust fumes on board.