It's every boat owner's nightmare: the hose line from the gas system's shut-off valve to the gimballed cooker has been damaged by a sharp stainless steel plate. Gas flows out and collects at the lowest point of the boat, in the bilge. The owner comes on board, looks forward to a nice weekend on the boat, starts the engine - Kawoom!
Gas explosions on ships have just as terrible consequences as a leaking combustion chamber in a diesel heating system. If the heater is more than ten years old, this can happen occasionally. Even with the 50-euro models without CE approval from China, which can be bought cheaply on the Internet and look as trustworthy as the almost identical models from Europe. While the crew dozes off in the cosy warmth of the evening, it can happen that the carbon monoxide flowing in with the warm air causes an unintentionally deep sleep.
Dangers lurk everywhere on board. That's why it's good to have alarm systems such as gas or CO alarms on board, which can be retrofitted for little money. We provide an overview of the most important systems.
Cooling water temperature warning device
Sounds the alarm before the engine gets too hot.If a floating plastic bag blocks the cooling water inlet, the engine can overheat. But this takes a moment. Long before the cooling water alarm signals a problem, combustion gases reach the now uncooled exhaust system at up to 300 degrees.
If there is a plastic water collector there, it may melt.
For this reason, there are retrofittable temperature sensors such as this model from Vetus (around 95 euros, plus alarm transmitter), which can be easily integrated into the exhaust pipe.
To do this, simply drill a hole in the hose near the motor, push the sensor through and secure it with a nut.
Gas alarm
Sensitive detector.Propane gas is not only colourless, but also heavier than air and highly flammable. On ships, this is a dangerous combination, because if there is a leak in the pipe from the gas cylinder to the burner, propane seeps quickly and completely inconspicuously into the lowest point of the ship: the bilge under the floorboards. If an electric bilge pump or the engine is then started, it can ignite. For this reason, the propane gas system should be checked by a specialist every two years. However, a gas alarm is also a good investment, as it recognises the escaping gas even at low concentrations and sounds a loud alarm. There is a wide range of models available on the market that are operated by battery or via the on-board power supply.
The TriGasAlarm (approx. 90 euros, available e.g. from Fritz Berger) constantly draws attention to its readiness for use by means of a green LED light.
The model from BEP (from 320 euros) has been specially developed for use on boats and enables the connection of several sensors in different segments of the boat. A magnetic switch can also be connected to remotely unlock the propane cylinder.
The gas sensors from Pilot (from 140 euros, e.g. from SVB) have almost the same functions and can be installed on any boat.
Simple gas detectors without remote sensors are available for around 20 euros (Firlarm, 230 volts, Amazon.de), around 75 euros ( AMS P100, Amazon.de ) and approx. 110 euros (AMS Kombialarm Compact, Fritz Berger).
All-Warner
The Spexor has many functions. Barely larger than a can of cola, the small device from Bosch constantly monitors its surroundings with its numerous pressure, noise, temperature and motion sensors. If several parameters change (e.g. in the event of a break-in), the Spexor immediately sounds the alarm - acoustically and via push notification on the smartphone.
But that's not all: the Spexor's software is constantly being developed and the device has many other monitoring programmes, such as an alarm in the event of frost or poor air quality. Thanks to the integrated eSim card (mobile phone connection included for one year), the Spexor does not require WLAN, and the integrated battery powers the device for up to three weeks if the mains power fails. It costs around 250 euros >> available at Amazon .
Fire detector
Smoke in the air. The familiar and common household fire alarms work according to the scattered light principle and should not be missing on board a yacht. Inside there is an infrared light-emitting diode, which is activated at regular intervals, and a light-sensitive sensor. If there is smoke or soot in the air, the infrared control beam is reflected onto the photodiode and an alarm is triggered. Available from 15 euros >> e.g. here .
Water alarm
When the sea gets into the boat. If the yacht is not made of wood, the bilge should be almost dry. Automatic bilge pumps ensure that any water that gets in is quickly drained out again - but the skipper often doesn't even realise when his boat is taking on too much water. The small alarms are intended for use in homes, for example if the washing machine overflows, but as most systems are battery-operated, they are also suitable for use on board.
The Water detector from Mumbi (approx. 10 euros, Amazon) has a contact on the back.
The Waterswitch from Kemo (approx. 11 euros, Amazon) must be operated with a stabilised 9 to 12 volt power supply unit.
Battery monitor
Before it is completely empty. Battery capacities are limited, especially on smaller boats. The batteries are often used in combination to start the engine and supply the on-board electrical system. It's nice if there are still cold drinks in the fridge at the end of a day at anchor - but fatal if the cold fridge has drained the battery to such an extent that the engine no longer starts.
The small Battery Protect module from Victron (approx. 62 euros) can be programmed via Bluetooth and disconnects less important consumers from the battery in good time before it is discharged too deeply.
The Battery Alarm from Victron fulfils the same task, but only visually indicates whether the voltage is too high or too low.
The Votronic Battery Protector 40 (approx. 62 euros) is available in the motor version with a higher switch-off threshold so that the voltage is sufficient for starting.
Carbon monoxide alarm
No poison in the air. Wherever fossil fuels are burnt, carbon monoxide can be produced as a result of incomplete combustion. If the toxic gas is absorbed through the respiratory tract, it binds more strongly to haemoglobin than oxygen and thus prevents sufficient oxygen transport. Carbon monoxide poisoning can therefore be fatal within a very short time. For this reason, a CO detector should always be installed near gas cookers and diesel heaters.
Such a Detector from Nemaxx (approx. 20 euros, Amazon) displays the CO concentration and gives an acoustic warning of excessive levels. A concentration of 100 PPM (parts per million) already causes headaches and dizziness.
The model from Kidde (approx. 20 euros, Amazon) has a 10-year guarantee.
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