The silent killer
Carbon monoxide latest
It’s not just for exam day, it saves lives says BSS representative David Fletcher
The requirement for a CO alarm in all boats with accommodation became a BSS requirement in April. This applies to all boats immediately, even if your examination was as late as March and you will not be checked for another four years. The BSS office tells us that the examinations taking place since April are recording less than 10% failures on CO alarm requirements. This is a really good result when the estimates were that perhaps a third of boats did not have them.
Of course, alarms are not just for the day of the examination; they have to work every day. So there is a job to be done, checking them by pushing the button. There are businesses that sell testing gases to check the function, but there is no need for these in a boating environment—pushing the test-button is perfectly adequate. If you really must live-check it, find a petrol engine and put the alarm in the exhaust gas plume.
Remember that any BSS requirement is designed to meet the need of a navigation authority, which should be satisfied that a boat is safe enough that it will not be a risk to other users or the authority’s own facilities. It is not about protecting a private boat user. So BSS is a minimum requirement for the navigation authority. There is no requirement (for example) to service the engine, but that is something that the owner will have to consider.
This is not the end of the CO issue in BSS circles. For some time, a small number of examiners have been carrying sensitive CO monitoring recorders while working on board. There are two issues: one of protection for examiners who are entering boats with no idea of the condition of stoves, water heaters and cookers; and secondly, to see what is happening while the examination is in progress. And results from the monitoring recorders are showing how widespread the incidences of low level CO are. These levels may not be enough to set off an alarm, but they are of concern for long-term exposure. Do you get headaches on board?
Ventilation considerations
BSS has been considering what is happening in boat cabins with regards to ventilation, air changes, the dispersal of toxins like CO and also tiny propane gas leaks.
The most recent live trials were done at Mercia Marina and involved releasing sample gases outside a boat to look for the effects as they were blown through cabin spaces. It was this evidence, together with the horrific fatal accident on the Broads, which led to confirmation of third-party risk and the introduction of the alarm requirement.
The BSS also has a number of CO monitoring recorders deployed in residential boats in London, so that data can be gathered about low levels of CO in cabins, when there are a group of boats together. All this is about the risks to boaters, not from on-board stoves etc., but from the gases blowing into a cabin from another high-concentration source nearby and threatening life. The usual high-level sources are petrol engines, used for propulsion or with generators, and solid-fuel stoves. If the boat next door puts a load of fuel on the fire and smoke is blowing into your boat, what do you do? You shut the window. But if you are asleep, you need a CO alarm to do its work. Diesel engines and Webasco-type heaters are not very high CO sources, if well maintained, but the noise and fumes are not pleasant.
The BSS ventilation requirements for boats have long been a source of contention. Historically they have required an air-gap based on how many appliances or burners are present, and a presumption that they are all working at the same time. This is rather typical of conservative engineering assumptions, when safety has to be engineered into design and is not dependant on user’s actions. For hire-boats, this ventilation is a requirement but, for private boats, it is advisory because it is a first-party risk. About 20% of private boats do not meet this recommendation. But fixed ventilation is an important element in keeping us safe. There is no minimum requirement for private boats because it is not of concern to a navigation authority, but why would a prudent boater not comply for their own safety?
CO in the galley
All combustion produces some CO but a well-maintained cooker generally produces very little, and the ventilation allows air changes so that fumes disperse.
The CO alarm manufacturers say not to place the alarms over the stove, so that there are no nuisance alarms. But this doesn’t mean that there is no CO: the examiners’ monitors have shown that gas grills give off a high level of CO when they are first lit. This is because the metal is cold, causing incomplete combustion. It can also happen if a large kettle or pan of cold water is placed on a hob. There is nothing to worry about if the ventilation is good. The latest CO leaflet talks about keeping a window open, but if your fixed ventilation is substandard, the weather is poor and windows are shut, there will be detectable CO in the galley. The concern about this is the effect of long-term, low-level exposure, and little is known about lower safety thresholds.
So, there will be an on-going debate about the ventilation requirements as we understand more, but they are unlikely to be changed soon. They are conservative but not unreasonably expensive to comply with. The concern is about low-level CO from onboard appliances, although a first-party risk, which could be adversely affected by a reduction in ventilation area. What can you do? Make sure your alarm(s) meet the BSS requirements and test them often by pressing the button. Think about what to do if an alarm goes off. If your ventilation does not meet the requirements, get extra ventilation grilles put in. Maintain your stoves, cooker, heater etc. If you are getting persistent headaches when on board, think about what is going on and check, check and check again; it could save a life.
