Are you exhausted at the end of the season?
Inspecting and maintaining your engine’s system is vital.
Here’s how to do it!
Starting at the engine end, it may not be absolutely clear which is the last part of the engine and the first part of the exhaust system. So the best thing is to start with the water injection elbow and pipe, usually rubber, bringing water from somewhere on the engine cylinder head. This must be rated for hot water. Car heater hose is quite suitable in this case. Check for perishing and general condition, and look for leaks, particularly at both ends. The hose clamps should be of stainless steel, free from significant corrosion and gripping the pipe tightly, but not so tight that the pipe is reduced in diameter by more than a millimetre or two. Over-tightening of hose clamps is a common mistake that leads to premature failure, as the edges will actually cut into the hose in extreme circumstances. Then work your way back along the exhaust system, looking for damage and deterioration to components and checking the tightness of the exhaust clamps. Signs of blow-by due to loose joints are evident by staining of the pipe next to the hose. But again, be wary of over-tightening tee-bolt type clamps. When inspecting an exhaust system you aren’t familiar with, do check that all the components are of the right quality, particularly the hose. Replace anything that doesn’t come up to scratch. A common fault is lack of support, whcih can be dangerous and will certainly shorten the life of the system as stress is applied in places it shouldn’t be. If you have any doubts about the quality, design or the way your system is assembled, your exhaust supplier will be happy to advise. Draining silencers always have some water in the bottom of them and should be supplied with a drain tap or plug. Freezing can cause damage to the silencer as the water expands, so its wise to drain them off if the temperature is likely to fall to +5 deg C for fresh water and 0 deg C for salt. This leaves a bit in hand for the weathermen to get it wrong! You should also drain all silencers before you lift the boat if there is any danger of the crane, lorry or ship putting the boat in a steep enough bow down angle to allow water to run forward out of the silencer. Take particular care if the pipe entering the silencer is anywhere near the minimum one in eight gradient. Draining silencers for transport might seem unnecessary, but imagine what happens to the water in the silencers when the transporter has to make an emergency stop. On ships, boats are often carried as deck cargo, strapped down laterally. One good roll in rough weather and bingo – you may have a hydraulically locked engine and a very large bill.
Turning to winterisation… As the season slowly comes to a close and our thoughts turn to the winter months, not only is it time to think about winterising boats, it is also an ideal time to think about, research and carry out any additional work. One of those things is looking at the engine noise…
Marine 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 amplifed 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. There are several ways of reducing engine noise. Adding weight and thickness to the bulkhead with insulation layers in one way to help reduce noise transmission. Reducing the hardness and altering the texture of the bulkhead facing will absorb more noise and stop bouncing it around and possible even amplifying it. Just like double or triple glazing windows at home, it pays to constuct one’s noise barrier using multiple layers of thin material rather than one simple layer many times thicker. If you cocoon the engine with noise insulation you can reduce ariborne noise by 85% and transform the comfort for all on board. Remember structure borne noise and exhaust noise are separate subjects. Insulation should be used on as much of the total surfaace of the engine room as possible. Cut around pumps, filters and electrical items, but don’t leave large areas of hard surface for noise to bounce off. Hatches and steps must fit neatly and should have a nice tight cushion such as hatch tape. Bulkheads around the engine should go right down to the hull. Don’t leave openings where noise can leak forward – for instance under a cabin floor. Remember that fuel and water tanks absorb in front of them, at least insulate the actual tank. The insulation panels can be stuck with conventional thixotropic adhesive such as Evostick or Dunlop Thix-o-fix. The containers will have manufacturers instructions printed on them and these should be followed carefully including those related to health and safety and disposal of empty containers.