Alarms with life-long batteries
Every year people are killed in fires because flat or missing batteries prevent the alarm from alerting the victims to the developing danger and this is why alarms with lithium or long-life batteries are best for boats.
Alarms sold as 7 or 10-year, or even long-life units will probably have lithium batteries provided as a sealed-in power pack.
Both ionisation and optical long-life alarms are slightly more expensive than ones with replaceable batteries, but you will save on the cost of replacing alkaline or standard batteries over time.
However, be prepared to replace the alarm sooner than 10 years on a boat, because the damp atmosphere in the cabin may affect a power unit's lifespan.
Standard battery alarms
Although slightly cheaper than lithium battery types, these run off 9-volt batteries that you will need replace at least once a year, or probably more often because of the damp cabin atmosphere.
The alarm will beep regularly when the battery needs replacing.
Hush or silence button
This is a crucial feature on a boat if you don’t want lots of false alerts.
When the ‘hush button’ is pressed, it silences the alarm for a short time such as if activated when cooking.
The alarm may remind you that it’s been silenced by ‘chirping’ and/or by displaying a red light.
Interconnecting or linked alarms
Some alarms connect to each other so that, when one senses smoke, all the alarms sound. If you choose to fit more than one alarm on your boat, we recommend installing one that can be interlinked.
This makes sure everyone hears the alarm. These alarms are also useful for anyone who thinks they may need extra help to be woken from deep sleep or for some people with hearing difficulties.
Interconnection can be by 12v bell wire or simple wireless systems.
If anyone aboard has impaired sight, hearing, reach or mobility, specific advice in selecting the right type of alarm or adaptation may be available directly from alarm manufacturers or specialist suppliers.
Battery alarm with emergency light
If the alarm goes off, the emergency light may illuminate the escape route.
These are designed to react to more than one element or property of a fire. They can increase performance and reduce false alerts. Currently available alarms have either optical and ionisation combinations or they have a smoke detector and carbon monoxide (CO) detector mix.
Alarms with CO sensors are designed to protect people from CO caused by domestic appliances (boilers, stoves, etc) or from exhaust fumes (outboard engines, generators, etc).
CO is the highly toxic gas that stops the body from absorbing oxygen properly.
These alarms are at the more expensive end of the DIY domestic smoke alarm market. CO has different characteristics compared to smoke, so you may need more advice from the supplier for fitting it in a boat.
Any CO alarm unit for boat use is recommended to meet BS EN 50291 as a mimimum and BS EN 50291-2 for greater assurance. Also look for the BSi Kitemark or LPCB horseshoe certification mark supporting the manufacturer's standards statement.
Unless your craft is on permanent shoreline supply, or you are confident of having sufficient capacity in your boats battery and inverter system to meet all your 230v AC main electricity needs, these alarms are probably not for you. They have to be ‘hard-wired ‘in’ and should be installed by a competent person.