Boats

Boats - Estuary, Coastal, River, Canal.

River and estuary/coastal water craft present similar problems to caravans but the operating environment is obviously harsher. Canal boats have specific characteristics of their own. Fitting a phone usually involves the provision of an external powers supply and an external antenna. If full hands free operation of the phone is required a car kit can be fitted.

The use of a mobile phone as a a primary safety communications system as a substitute for maritime VHF communications is not recommended. The range of a phone is unpredictable, it cannot be heard by other craft and it cannot receive coastguard broadcast information. It may be better than nothing but estuary and coastal water vessels should carry VHF communications.

Masters of small craft should be aware that GPS and GLONASS reception may be degraded by the use of mobile phones (with or without external antennae) on board their vessel.

Antenna Fixing - Wood/Fibreglass superstructures.

In most cases for a simple fit in river boats or craft used ocassionally in estuaries a bodymount such as the Base 2000 is the preferred option in that it is simple to fit (single 14mm or 19mm hole fixing) and the antenna element can be unscrewed without tools so it can easily be removed for maintenance and storage if desired. The antenna base is resin and stands salt water well. The antenna radiator is also capable of standing salt water spray and immersion.

A sheet of alumium approximately 12" square (or sticky aluminium foil can be used) must be affixed to the inside surface of the craft and the mounting hole drilled in its centre. Mounting on the outside isn't recommended both from the aesthetics of the fixture, protection of the surface and the difficulty of achieving good earth braid/plate contact (the earthing prongs are on the lower part of the antenna installation).

The antenna should be mounted in a position to allow easy access and also sufficient earth plane. It is often convenient to mount it over a built in cupboard or wardrobe to allow the cable to be brought down inside the craft out of view.

If for any reason a roof mount isn't acceptable then a temporary solution is to use a sleeve dipole such as the window clip mount however these are now only available for 900MHz (Vodafone/Cellnet).

This can be placed over a sliding window or mounted externally on a suitable pole. The cable connector will need protection against the elements if mounted outside (see self amalgamating tape).

This would make a perfectly acceptable solution if it was required to carry an antenna in the craft which could be quickly erected for temporary use. It isn't recommended for a permanent installation.

For seagoing craft a better fit is a full maritime antenna,

Marine Antennae are connected using a UHF connector and adapter on the base. The threads on the adapter look the same on both ends but are not, the antenna base fits in one side only, the UHF plug in the other. Silicone grease or Vaseline very lightly smeared upon only the threads before assembly will ease disassembly at a later date. Once installed both the antenna base fixing and the UHF connector must be wrapped in self amalgamating tape to ensure a water resistant joint.

It is recommended for seagoing craft that the joint on the base of the antenna be disassembled every 2 years for the connectors to be inspected and the water-resistant tape to be renewed. The co-axial cable has a service life of approximately 5 years if left exposed to the elements.

When mounting marine antennae try to keep them as far as possible from the vessel superstructure and other aerials (eg VHF radio). No separate ground plane is required with this antenna. Co-axial cable must not be crushed or bent sharply. A minimum bend radius of 6" is recommended for the cable supplied.

Please note that neither the antenna or supplied mount is flexible - the aerial will not bend and should be lowered if overhead obstructions are likely to be encountered.

Power

Power is usually going to come from batteries within the caravan or from the host vehicle. Although most phone chargers take a fairly small drain compared with lights and other electrical fittings in a caravan the normal precautions against the vehicle battery becoming discharged should be in place. These usually involve some form of relay so that the car battery is disconnected from the caravan services once the engine stops.

Don't forget that the 12 or 24VDC supply within a caravan is usually coming from a battery with a very low internal resistance. Any cabling fault will lead very high currents flowing and unless suitable protection devices are in place (fuses or circuit breakers) the wiring loom will reach a temperature at which its insulation will ignite in only a few seconds. It is especially important to ensure circuits are suitably protected when adding to them. An electric fridge might be protected by a 30Amp fuse and it would be wrong to simply take a phone charger circuit on 5A cable from that without an extra fuse near the source to protect the wiring.

The simplest form of charging involves using a modified car charger. Mounted in a surface mount box this gives a neat permanent fixing for the charger lead and if combined with a simple holder is usually a very satisfactory solution.

In the example shown on the right the charger circuitry is contained in a box with a charge indicator light, a switch can also be fitted on the box but in this case the supply was externally switched. The power supply wires (12 to 28VDC) are brought in at the rear of the box which was mounted on the side of a cupboard.

The phone was usually hung on a simple bracket (shown below)

12-28VDC bulkhead mounting charger and phone clip.

£21.90

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