Digital CO alarm

Most boats have several sources with potential to emit carbon monoxide, the odourless yet lethal gas created by incomplete combustion of a multitude of different types of fuel, writes Rupert Holmes. Leaky inboard engine exhausts, cookers and heaters of all descriptions can be culprits.

The problem with standard carbon monoxide alarms is there’s no diagnostic functionality – if the alarm sounds everything that burns fuel must be turned off, the boat ventilated, and the crew need to get on deck to breathe fresh air. The situation is complicated as the threshold that triggers an alarm depends on the concentration of CO and length of exposure. It will therefore activate if a high level is detected for a very short period, or a lower level over a number of hours.

A unit with digital readout of CO levels has allowed me to gain a feel for the CO output of different devices. Cookers appear to be a problem, even if in apparently good condition – all of those I’ve tested appear to produce at least a little carbon monoxide, with alcohol stoves particularly bad offenders. Without the digital display of CO concentration on this device I’d not have discovered this, but now I know it’s worth checking before cooking a complex meal and proactively increase ventilation if necessary. If the alarm does then sound I know a new problem has developed that needs immediate attention. Given alarms with a digital display cost less than £10 more than a ‘dumb’ unit, they’re clearly worth the extra expenditure.

Price: from around £20.

■ Let us know about your most useful products, either new or old favourites. Send an email with a photo to pbo@ti-media.com.