David Fletcher has news of a study to monitor CO in boats.

Carbon monoxide (CO) continues to kill several boaters every year. The BSS requirement for alarms was introduced last year, accompanied by a significant press campaign, but there continue to be incidents, and the number of boats failing examination on this point continues to disappoint. The highest numbers of failures on private boats concern the amount of fixed ventilation. If this is your boat, you are at risk because there is not enough air movement to disperse the small amounts of CO contamination that are inevitable. Remember that the BSS is not about your safety; it is about the navigation authority discharging its duty of care to others.

Previously, I have talked about wanting to run some tests using CO monitors that record all levels of CO, so that we can see what the background level of this gas is in the normal living environment of our boats. There is a good deal that we do not understand about low levels of CO and the effects of ventilation and air change in boat cabins. We are measuring CO levels at parts per million (ppm) – 50ppm can make you very ill. The high-risk sources are petrol engines and solid fuel stoves, but any combustion equipment can kill if it is misused or not maintained.

All combustion generates some CO, but a well-maintained cooker generally produces very little, and the fixed ventilation allows air change to disperse fumes. The CO alarms are typically set to go off at 70ppm after 1 hour, so that there is no nuisance alarm. But it doesn’t mean that there is no CO. The concern is that little is known about the lower safety thresholds of long-term low level exposure.

Some BSS examiners have been carrying monitors during inspections for their own protection; they don’t know what they are facing as they enter a boat. They have found that gas grills give off a spike of CO when they are first lit. This is because the metal is cold, and this causes incomplete combustion. It can also happen if a large kettle or pan of cold water is placed on a gas 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 and the weather is poor with windows shut, there will be detectable CO in the galley. Graph 1 shows CO in a galley using a monitor.

A major new study is to start this year with boaters in London looking at CO levels, particularly the low levels that come from sources such as gas cooking, solid-fuel stoves, or wind-carried exhausts from adjacent boats and generators. CO monitors will be placed in many boats, so that both high and low levels of CO can be detected. The study is to find out the extent of these low levels, typically 1-10ppm.

But we wanted to get ahead of this and understand what is going on. There is no use having a lot of graphs if there is no information on what is happening in or around the boats. So we need good feedback from the boat owner along with the reports, to understand the boat, the ventilation, the kit on board, and the environment around it. Then we can relate the peaks to real events. This second part, to relate peaks or high levels to actual events or causes, is much more problematic.

We have had a number of these recording devices in use this spring and we are learning how to use them, where to place them and the reliability of doing these tests. The devices record data and we can produce a graph of the readings over time, showing the extent and frequency of spikes and how quickly the spike drops. What we don’t want to see is elevated levels of CO hanging around for hours. This would indicate a leak, where CO is getting into the boat continuously, or poor ventilation that prevents CO dispersing (see graph 2).

What can you do? Make sure your alarm(s) meet the BSS requirements and test them often by pressing the button. Think about and plan what to do if an alarm goes off. If your ventilation does not meet the requirements, get the extra grills put in. An easy way is to leave a top gutter window open, fixed open with a stop. If your ventilation is not up to standard, get it fixed. Maintain your stoves, cooker, heater etc. If you are getting persistent headaches when on board, think about what is going on and check, check, check – it could save a life.