Few upgrades transform a boat as much as a well-chosen navigation suite. Whether you run a 28ft RIB out of the Solent, a cabin cruiser across to Alderney, or a race boat campaigning the Cowes–Torquay–Cowes, the difference between a grainy old plotter and a properly networked system is the difference between guessing and knowing. But electronics are expensive, thirsty, and unforgiving of a rushed installation. Here is how to approach an upgrade methodically.

Start With the Passage, Not the Product

Before you look at a single specification sheet, write down the passages you actually do and the ones you intend to do. A boat that never leaves the Solent has different priorities from one that crosses the Channel in fog or runs overnight to the West Country.

• Coastal day cruising: a good chartplotter with a bright, sunlight-viewable screen and reliable position input is the core. AIS receive is cheap insurance in the Solent and around the Thames Estuary.
• Offshore passage-making: add radar, AIS transponder, and a second independent position source. Redundancy matters more than screen size.
• Racing and high-performance craft: prioritise fast update rates, high-contrast displays readable at 40 knots, and instrumentation that feeds speed, heading and wind without lag.

The single most useful question is what you cannot currently see. If the answer is "shipping in fog" or "the entrance at night", that points clearly at radar and AIS rather than a bigger display.

Power Budget and Electrical Reality

Offshore powerboats rarely have generous house banks. Modern multi-function displays, radomes, and transponders can add 5–15 amps of continuous draw, and that figure climbs sharply when you add a second station or a 4kW radar.

• Audit your existing battery capacity and charging. A twin-outboard RIB with a modest house battery will struggle with a radar and a large plotter running for six hours.
• Run separate fused feeds for the navigation suite rather than daisy-chaining off one breaker. A single fault should never take out the whole helm.
• Use proper tinned cable, correctly sized for volt drop over the run. Voltage sag is the most common cause of "random" electronic faults at sea.
• Consider a dedicated electronics battery or a DC-DC charger if you are adding significant load.

None of this is glamorous, but a system that browns out at 3am off Portland is worse than useless.

Installation Space, Viewing Angles and Helm Ergonomics

Measure twice. Displays have grown in size while cockpits have not, and a 12in screen that looks sensible on the showroom floor can block your view forward or foul a throttle lever at full lock. Check clearance for:

• Screen height and angle — you should be able to read it standing at the helm in a following sea, not crouching.
• Cable bend radii behind the unit, especially for NMEA 2000 backbone and Ethernet runs.
• Radar scanner siting: clear of the AIS antenna, away from mast clutter, with a clear 360° arc. On a RIB, a scanner mounted low on a radar arch will be blinded by spray and crew.
• Transducer and GPS antenna placement, keeping GPS aerials clear of radar and VHF transmissions.

On open boats, check that screens are genuinely waterproof to the standard claimed, and that any flush-mounted unit drains properly.

Radar and AIS: What Actually Helps Offshore

Radar and AIS do different jobs and you want both for serious offshore work.

• Radar sees what AIS cannot: unlit fishing boats, pot markers in poor visibility, squalls, and the coastline itself. Broadband solid-state sets are lighter, low-power and instant-on, which suits fast craft well.
• AIS receive gives you identity, course and speed of commercial traffic, ideal for crossing the TSS in the Channel.
• AIS transmit makes you visible to ships and to other race or cruising boats, genuinely valuable when you are small, fast and hard to see on a ship's radar.

Bear in mind that AIS only shows you vessels that are transmitting, and it will not show you a drifting pot buoy or a wooden fishing boat. Use it as one layer of awareness, not as a substitute for looking out of the window.

Networking, Integration and Data Standards

Mixing brands is normal and often sensible, but only if the data can move between them. Check for:

• NMEA 2000 for instrumentation, engine data, and heading sensors.
• NMEA 0183 for older autopilots, VHF DSC radios and some AIS units.
• Ethernet for radar, sonar and sharing charts between displays.

Decide whether you want one manufacturer's ecosystem or a best-of-breed mix. Charts matter too: check the coverage and update costs for UK and near-continent waters, and confirm the chart card you buy actually covers the Channel Islands and French coast if you cross regularly.

Commissioning, Sea Trials and Ongoing Maintenance

An upgrade is not finished when the last screw goes in. Book a sea trial in representative conditions — ideally with some sea running and, if you can manage it, reduced visibility. Verify:

• Position, heading and course over ground agree with a known reference.
• Radar aligns with the chart and with visual targets.
• AIS targets appear correctly and your own transmission is being received.
• Every function works on every display, including the backup.

Afterwards, keep it reliable. Flush exposed connectors with contact cleaner, keep a spare fuse and a printed wiring diagram aboard, and update firmware at the start of each season rather than the night before a race. Practise using the kit in daylight so that night and fog work feels routine — the crew who know their electronics before they need them are the ones who stay calm when the visibility closes in.