`Waterproof' is what it means, and this is the highest category. You can install waterproof equipment anywhere you like and it will stand up to both spray and solid water. For RIB use, you should aim for waterproof electronics even if it means paying extra. `Weatherproof' and `Splash-proof' mean much the same thing, they will generally withstand water coming down such as rain, but will certainly not stand immersion. In a RIB, water comes up as well as down and if you go for this cheaper option you will need to provide some protection for the electron­ics. Often this means protecting the connections at the back or the slot where an electronic chart cartridge fits in. Incidentally, roller ball controls are generally neither splash or waterproof.

From the wide selection of navigation electronics there are three main elements on which to concentrate: the Compass, the GPS / Electronic chart and Radar. With all three you can navigate with a consid­erable degree of confidence in virtually any conditions. Your pocket, the available space or the weight may limit the choice, but you can get by with two out of three and still cope with most conditions. The compass is essential and can be combined with the GPS/electronic chart or the radar to provide the vital heading reference, so let's concentrate on that first.

Modern electronic compasses are far superior to the swinging card magnetic com­passes in terms of giving a stable reading. The electronic compass is still magnetic, but the heading is sensed electronically. One big advantage is that the sensor unit can be located anywhere in the boat to give it a comfortable ride and they also come with a variety of display formats so that you can choose the one that suits you. All the major instrument manufacturers; B&G, Cetrek, Navico, Autohelm etc offer electronic compasses based on the standard 4 inch square display head, and KVH has its unique display which is probably one of the easiest to read and use.

With compass displays you have the choice of digital and analogue displays. The digital type are surprisingly easy to use provided that the numbers are large. Analogue displays come in two forms, one rather like a compass card and the other a simpler left/right indicator showing which way to steer to get back on to a preset course. Combination displays are available, but simplicity is the key to success and the left/right type is one of the best when you get used to it. It saves having to interpret the display to work out which way to steer. A quick glance tells you all.

In the choice between a radar and a GPS/electronic chart, the latter wins hands down. The radar presents you with a great deal of useful information, and the new LCD displays produced by Furuno, Autohelm, Raytheon and Apelco are compact, reliable and waterproof, but the real problem is the relatively large antennae. Modern enclosed antennae will stand up to RIB use, but it is a big lump to mount high up in the boat. Also, the radar display does need careful interpretation to understand what is being shown and this is not always easy to do with the rough ride of the boat. You need to concentrate on the display to get good information out of it and the average RIB is not good for this type of concentration. So,have a radar if you want to, but if it's a choice between the radar and the GPS/electronic chart, then go for the latter.

Both of these will help you navigate in fog and at night. In fog, the radar will show other craft around you if you concen­trate on the display, something the GPS/electronic chart can't do. However, an electronic chart will show you where you are in relation to the land and navigation marks, and with a highly manoeuvrable RIB you will generally see other craft before you hit them. The fog is rarely so thick that you can't see for 200 metres or so, which gives you plenty of time for avoiding action provided you keep to a moderate speed (which you should do even if you have radar!).

Many Ribsters consider the GPS as an essential navigation tool for RIBs. It certainly is, but on its own it does have limitations. You can navigate with the GPS by using waypoint navigation, but used in conjunc­tion with the paper chart. Some GPS units only give numbers and those numbers do not mean much until they are translated into a position on a chart. However, modern GPS receivers are cheap and mainly water­proof, and with superb features such as the `Steer-To' and `Plotter' screen which enables one to steer accurately to the next waypoint, they are an excellent navigation tool in the RIB. Entire routes can be programmed in, which then automatically updates the range on the Steer-To screen each time a waypoint is met, giving one the new heading and Steer screen for the next waypoint in the route.

A permanent installation is better than a portable, but with a portable you can take it home after use. The portables are generally cheaper, but the limitation here is the small size of the screen which can be difficult to read in the motion of the RIB, especially if wet.

The very best solution for navigation is to have an electronic chart combined with the GPS. The electronic chart is like a navigator's dream! It shows you where you are in relation to where you want to be in real time and it allows you to navigate with confidence, even in adverse conditions. Position information comes from a GPS receiver which may be separate or may be built into the chart unit itself. A big advantage is that you can plot all your navigation before you leave harbour and then it is simply a question of keeping the position cursor on or near the plotted route line.

The cartography for the electronic chart is held on cartridges which are inserted into a slot on the unit. These slots are rarely filly watertight which can be a problem, but some recent electronic chart units have a separate chart reader which can be mounted in the dry and which can hold 2 or 4 cartridges so you won't need to change them on most journeys. The latest Raytheon Raystar 198 uses this system and is also a portable unit, so that it can be taken out for security when you leave the boat. However, it does have a fairly small screen which may not be easy to read in a bouncing RIB and you should always go for the largest possible screen.

Cetrek's latest unit, the Chartnav 350 meets most of the RIB criteria. It has a large, fully waterproof screen and a separate waterproof control panel. Separating out display and control panel means you can mount both where they can be most easily used. This chart also has the separate chart reader which can be mounted in the dry. The Lowrance Global Map has proved popular with Ribsters and again has a separate chart reader which can be mounted in the dry. For ease of use, the Navionics LCD 11 unit is one of the best. Developed originally for use in very high speed racing boats, it is designed to work virtually automatically. The Auto Zoom feature always keeps the current position and the next waypoint on the screen, and adjusts the range automatically. A window displays the course and distance to the next waypoint in large numbers.

There is a wide choice of electronic chart units on the market. Go for the largest waterproof display you can afford if you intend to do serious electronic navigation. Smaller displays will do the job, but just when you need them most you may find yourself struggling to read the display, particularly if you are trying to drive the boat as well. If you have a separate GPS supplying position informa­tion you will still keep some electronic help if the chart screen fails. Portable units can be viable, but they tend to have a short battery life and if you are going to make a permanent installation go for a larger display. Portable GPS receivers are coming down in price all the time and can make an excellent back up system particularly as they do not rely on the boat's electrical system which can often be the cause of electronic failures. If you are going to use electronics to navigate your RIB then make a strong commitment to it and try to ensure that everything is as reliable as possible and professionally installed.

You can make your boat like an electronic Christmas tree by adding a whole range of instruments. A depth sounder can be valuable if you work inshore or are looking for wrecks. A log is less use because you already have speed informa­tion from the GPS. Wind information is generally for sail boats and the rule should be to keep the installation as simple as possible so that you can find the information you want at a glance.

Most of all, find the equipment that suits you and that you feel comfortable with, then you will find the challenge of navigation most enjoyable and a satisfying achievement.

Dag Pike