FITTING A SILENCER
SILENCED EXHAUST MAKES A BIG DIFFERENCE
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It’s a good idea to use exhaust paste
such as Firegum at either end. This
aids installation by lubricating the joint, but
will then set hard once heated and make
the joint more secure and gas-tight.
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First step was to remove the old exhaust. This was a simple
matter of removing the lagging, undoing the two Jubilee clips
and attempting to pull it off the exhaust stub and the skin fi tting. This
wasn’t too hard, but on corroded systems might require a hacksaw.
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The new exhaust is now clamped on. Pull the lagging back to allow installation, before
re-installing to cover the hot exhaust pipe once the ends are clamped on. I then used
an extra length of lagging to wind around the exposed pipe end and clamp, securing with a
twist of copper wire for extra safety. The pipe can then be secured with brackets to ensure it
can’t move and melt or set fi re to anything – like most exhausts, it gets extremely hot.2
The standard exhaust comes in a 2m length, and I’d need
the full length for my installation. It consists of a stainless
pipe with a silencer sealed towards one end. It’s all insulated
inside a sheath and then goes inside a length of air ducting.3
Make sure you are using proper hose
clamps. Simple worm drive Jubilee
clips aren’t good enough for this type of
application – a heavy duty stainless clamp
that applies pressure more evenly and that
can be tightened enough to crush the pipe
onto the spigot is important.
I took a reading with an iPhone app before
and after, held 10cm above the exhaust.
With the old, unsilenced exhaust, it
averaged 91.4dB. With the new it averaged
79.4dB. That 12dB is enough to make an
appreciable difference – remember that
decibels are a logarithmic scale, so the
perceived volume is approximately halved.
Walking down the pontoon you can now
hear a gentle hum, whereas before there
was an intrusive roar. It’s made a big
difference and I no longer feel guilty about
fi ring up the heater in a quiet anchorage! BEFORE The reading averaged 91.4dB AFTER A much lower 79.4dB average