“If all else fails read the instructions” 

RYA Cruising Manager, Stuart Carruthers, highlights how improvised modifications can result in unsafe operation.

I am sure that many of us have heard or even used that phrase, particularly at times when we have bought something new and can’t wait to get it home, unpack it, plug it in, switch it on and expect it to work like clockwork.

When nothing happens we grab the instructions and try to work out what went wrong. That may be fine if it is the latest must have gizmo, but it is definitely the wrong approach when it comes to using items that may not have been made for the intended purpose you have bought it for.

I have been involved in the analysis of two accidents very recently that have been caused as a direct result of improvised modifications. Both modifications were to the exhaust outlets; one caused death by CO poisoning, the other a fire which lead to the total loss of a vessel.

Recent accidents

The CO poisoning accident happened on a Bayliner 285 motor cruiser on Lake Windermere, Cumbria on 1 April 2013. On investigation the MAIB found that a portable petrol-driven generator had been installed in the motor cruiser’s engine bay to supply the boat with 240v power.

The generator had been fitted with an improvised exhaust and silencer system which had become detached from both the generator and the outlet on the vessel’s side. As a result, the generator’s exhaust fumes filled the engine bay and spread through gaps in an internal bulkhead into the aft cabin where a mother and daughter were asleep.

When the owner of the boat awoke in the boat’s forward cabin, he was suffering from carbon monoxide poisoning but was able to raise the alarm. The mother and daughter could not be revived.

More recently, on 14 January 2014, a 14m wind farm support catamaran caught fire 11nm east of Lowestoft. Three crew members on the vessel were unable to extinguish the fire, which spread rapidly throughout its GRP structure forcing them to abandon to a life raft.

Detailed examination of a similar vessel revealed that the heater exhaust pipe from a diesel fired air heater had been modified to route through a single walled, uninsulated, inverted U-pipe on the main deck to prevent sea water ingress through the exhaust overboard. As originally built, the exhaust pipe was of a fully insulated twin wall construction to prevent the hot exhaust gases of around 450°C from overheating the surrounding area.

Initial MAIB findings suggest there is compelling evidence to show that the source of the fire was caused by the uninsulated single walled section of exhaust pipe which ignited the surrounding plywood structure.

Closer to home

These are two of the more extreme examples, but there are others much near to home! How many of us buy some natty piece of electronics at a boat show and for simplicity wire it to the battery or some convenient terminal because there is no spare or convenient fuse? Does this look familiar?

Correct fuses and the correct wiring are important and yet are often paid lip service. A fuse prevents excessive current being drawn by an electric circuit when the current exceeds a certain limit. This protects the circuit from overheating and the surroundings from fire or damage in the case of an overload or short circuit.

Correct size cables are also important for low voltage systems. If the cable is far too small to carry the intended current then the cable will heat up and potentially cause a fire. Generally the longer the cable-run, the larger it needs to be. I could give other examples but I hope I have made a point about improvisation.

Simple lesson

The lesson is really quite simple; read and adhere to the manufacturers’ instructions.

In the cases above, the manufacturer gives clear, detailed instructions on how to use the equipment and how to install it. Clearly some equipment is just not designed to be modified and if it is then you run the risk of operating it unsafely. Where equipment has been designed for the purpose you intend to use it for then a qualified installer should be fully conversant with the installation instructions and a competent DIYer should ensure they are fully conversant with them before starting the work.

Stuart Carruthers, RYA Cruising Manager