Driving straight ahead in reverse with a trailer is not easy for the inexperienced. It gets really complicated when there is a boat on top and it has to be manoeuvred around obstacles or onto a slip ramp. There are more pleasant things. Steering in the opposite direction, the delay when turning in, the unfamiliar distances, lack of practice - an unloved task for most boaters.
It is therefore all the more surprising that no trailer manufacturer has yet come up with the idea - not even for an extra charge - of equipping their trailers with a reversing camera, as has long been common practice as a parking aid in cars. A simple camera that shows where the trailer is moving is sufficient. Or a retrofittable complete solution that can be "plug and play" onto any trailer.
But there is an inexpensive alternative: a commercially available car reversing camera set that you can retrofit yourself. We have tested whether this also works for use on a trailer.
Installation on the car is child's play
The Auto-Vox M1W is one of the most popular retrofit models for cars, costing only around 75 euros in specialist shops or online. The scope of delivery includes a small 4.3-inch monitor (smartphone size) with good resolution and suction cup for the windscreen, a small camera that can be stuck behind the number plate and a transmitter unit with antenna that transmits the data from the camera wirelessly, plus cables and cable ties.
Installation in the car is child's play: the monitor is simply plugged into the cigarette lighter and is immediately ready for use. It even has a USB port so that the only socket is not completely blocked and a smartphone or sat nav can also be charged.
Mounting is trickier on the trailer side. The camera is usually attached behind the car's licence plate with a glued-on bracket. It is fitted with two video plugs (cinch), which are plugged into the small transmitter unit that is to be mounted on the car inside the tailgate or behind the rear lights. Power is supplied via a positive and negative connection cable. The negative connection is routed to the car body (earth) when installed in the car.
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The camera is not intended to permanently transmit what is happening aft, it should only be used as an aid for reversing or parking. For this reason, the positive cable is usually connected to the car's reversing lights, which are activated via a switch in the gearbox. When reverse gear is engaged, the reversing lights light up and the reversing camera starts transmitting.
The connection to the trailer is more difficult
The problem with connecting to the trailer is that most trailers do not have a reversing light. Although the car sockets offer the option of connecting a 13-pin socket on the vehicle side, because a reversing light is not prescribed for trailers, there is usually no cable in the trailer frame leading to the light strip. The necessary positive cable would therefore have to be laid yourself, which can be medium to difficult depending on the design and experience of the installer. It should also be borne in mind with new trailers that tampering with the electrics may invalidate the warranty.
Cars with a 7-pin socket do not offer any option for installation via the reversing lights. In this case, it is either necessary to convert the car and trailer to a 13-pin coupling and wiring - which can sometimes be inconvenient if extra cables have to be laid from the tail light to the socket. The alternative here would be to operate the camera only via the positive lead of the tail lights. The disadvantage is that the camera then always transmits as soon as the lights on the vehicle are switched on. When driving straight ahead, the monitor would then distract from the traffic and would have to be switched off.
When mounting the camera, it is important that it is positioned as close to the centre of the light strip as possible so that the distances to both sides of the trailer are the same; otherwise obstacles and gaps in the road can be misjudged. If the licence plate is not mounted in the centre but offset to the side (as is often the case), the camera must be glued directly to the centre of the light strip.
The reversing camera in use
The camera itself is certified to IP68 (dust and waterproof against permanent submersion) and could probably even survive being dropped; the transmitter, on the other hand, is only IP67 (temporary submersion). For permanent installation, it and the cable connections (which are otherwise installed inside the car and are not intended for permanent outdoor installation) should possibly be protected by a plastic box, as they corrode over time.
The transmitter has a powerful output and, according to the manufacturer, can be received up to 100 metres away. The camera has a wide-angle lens with an aperture of 170 degrees and is therefore ideal for monitoring the entire stern width of a trailer boat at a distance of around one metre. The camera itself can also be swivelled up to 45 degrees upwards or downwards, making it possible to monitor the passage width of an overhanging hull. Six built-in LEDs, each with an output of 26 lumens, illuminate the surroundings at dusk or in the dark.
In practice, the reversing camera on the trailer proves to be a great help. When carefully approaching a slip ramp, a parking bay or a crane site, it always shows exactly the direction in which the trailer is travelling. A little further to the left, a little further to the right - the driver can immediately see on the camera what is happening, in which direction the rear swings out, and can also react to obstacles that would otherwise be outside his field of vision. The image is razor-sharp.
The distance warning range is set for mounting the camera behind the licence plate and may not be one hundred percent accurate if the ship is hanging far over the light bar. You can quickly get a feel for the distances and the display of the warning colours (which can be switched off) by trying them out.
To summarise: For most trailer drivers, such a small camera should be a huge benefit.
