Is A Small Boat Radar Setup Worth Having?

Q: 2. How much power does a modern radar use?

Solid‑state Doppler radars typically draw 20–40W in transmit and just a few watts in standby. They wake instantly, so you can leave them in low‑power mode and bring them up the moment visibility deteriorates. For solar‑reliant cruisers, this is a major improvement over older magnetron units.

Q: 5. Can radar really detect rain and squalls?

Yes. Most modern units include a Rain Mode that distinguishes precipitation from solid targets. Offshore, radar will often spot squalls long before you can see them — especially at night — giving you time to alter course or prepare for the gust front.

Key Takeaways: Modern solid‑state Doppler radar has overtaken older magnetron and FMCW (Frequency‑Modulated Continuous Wave) broadband units in almost every respect, delivering far better target discrimination and dramatically improved short‑range performance.

Power consumption is now low enough (typically 20–40W) to make radar practical even for solar‑dependent cruisers, while Doppler target colouring highlights collision risks instantly without relying solely on MARPA (Mini‑Automatic Radar Plotting Aid).

AIS and radar overlay have become standard practice offshore, and the latest scanners are genuinely useful at close quarters—whether you’re picking your way through an anchorage, dealing with squalls, or manoeuvring in restricted visibility.

Mounting still matters: mast mounts maximise range, gantries offer convenience, and self‑levelling mounts solve heel‑related issues.

One of radar’s most underrated benefits remains its ability to reveal rain and squall activity long before it reaches the boat.

What Radar Actually Does
Modern Radar Technology
Comparison of Radar Technologies
Radar Features That Matter on a Cruising Yacht
AIS + Radar: The Modern Offshore Standard
Weather Detection
Scanner Types and Mounting Options
Summing Up
Frequently Asked Questions (FAQs)

What Radar Actually Does

RADAR — Radio Detection And Ranging — transmits radio waves and measures the echoes returning from objects around you. The display shows these echoes as targets, allowing you to “see” ships, land, squalls and obstacles long before they’re visible to the naked eye.

Because radar is a line‑of‑sight system, maximum range is limited by the curvature of the earth. The higher the scanner and the higher the target, the further you’ll detect it.

radar range restricted by curvature of eart

The radar range is restricted by curvature of the earth

Radar helps you see what’s around you, but remote monitoring helps you know what’s happening when you’re away. For onboard alerts, see Sentinel Marine Monitoring.

Modern Radar Technology

Radar has undergone a quiet revolution. The old categories — “pulse radar” vs “broadband FMCW” — have been replaced by solid‑state Doppler pulse‑compression radar, now the standard across Raymarine, Garmin, Simrad and B&G.

Why Doppler Matters

Doppler processing measures whether a target is moving towards you or away from you. Modern systems colour‑code this automatically:

Closing targets: usually red
Opening targets: usually green
Stationary targets: neutral

This gives instant situational awareness without fiddling with MARPA.

Power Consumption

Solid‑state radars typically draw:

20–40W in transmit mode
2–5W in standby
Instant wake‑up (no warm‑up magnetron)

For solar‑powered cruisers, this is transformative.

Range

Modern radomes typically offer:

24–36nm maximum range
Superb short‑range clarity (0.1–1nm)
Beam sharpening for better target separation

The old “4kW” terminology is obsolete — solid‑state radars don’t use kW ratings.

If you want to see how the different radars compare in real cruising use, I’ve put together a detailed comparison table here.

Comparison of Radar Technologies

Technology	Pros	Cons	Status in 2026
Magnetron Pulse Radar	Long range, robust	High power draw, warm‑up time, poorer short‑range	Largely obsolete on small boats
FMCW Broadband Radar	Low power, instant on, good close‑range	Limited long‑range, now discontinued	Legacy technology
Solid‑State Doppler Pulse‑Compression	Best short‑range, Doppler target colouring, low power, instant on	More expensive	Current standard

Understanding radar is easier when you see how it fits into the rest of your navigation and communication gear. Our Electronics & Communication section explains the complete system—from AIS and chartplotters to NMEA networking.

Radar Features That Matter on a Cruising Yacht

Zoom Levels

Most radomes offer:

1/16nm to 24–36nm range
Wide‑area situational awareness offshore
Fine detail when approaching anchorages or reefs

MARPA (Still Useful, But Less Critical)

Modern systems track 10–20 targets, but Doppler has reduced the need to rely on MARPA alone.

A typical RADAR display

Range Rings

Still the quickest way to judge distance at a glance.

EBLs & VRMs

Essential for manual collision‑avoidance plotting and verifying CPA/TCPA.

Guard Zones

Set a circular or sector alarm around the boat — invaluable at night or in fog.

AIS + Radar: The Modern Offshore Standard

AIS and radar complement each other beautifully:

AIS shows ships that broadcast
Radar shows ships that don’t (fishing boats, steel yachts, unlit vessels)
AIS gives identity and CPA/TCPA
Radar gives physical confirmation

Overlaying AIS and radar on the same chart is now the norm.

Weather Detection

Some radars include Rain Mode, which distinguishes precipitation from solid targets. Offshore, this is gold.

On our Atlantic crossing, radar repeatedly spotted squalls long before we could see them — often giving us time to alter course and avoid a soaking. At night, this was worth its weight in gold.

Scanner Types and Mounting Options

Radomes

Best for sailboats:

Compact
Low power
Excellent short‑range performance

Open Arrays

Seen mostly on powerboats:

Higher resolution
Higher power draw
Not ideal for small yachts

Mounting

Mast mount (15–20ft above deck) gives best range but suffers when the boat heels.
Self‑levelling mounts solve this.
Gantry mounts are easier to install but can create blind sectors if poorly positioned.

Summing Up

Radar has evolved from a heavy, power‑hungry luxury into a lightweight, energy‑efficient safety tool that earns its keep every time visibility drops. Modern Doppler radars are astonishingly good at highlighting collision risks, spotting squalls and giving you a clear mental picture of the world around you — day or night, rain or fog.

If you sail offshore, cross shipping lanes, or simply want an extra layer of safety when the weather closes in, a small‑boat radar setup isn’t just “worth having”. It’s one of the most capable and reassuring pieces of kit you can install on a cruising yacht.

Written by Dick McClary, cruising sailor and yachting journalist, publisher of Sailboat‑Cruising.com and admin of the Liveaboard Sailboats for Sale community.

Frequently Asked Questions (FAQs)

1. Do I really need radar if I already have AIS?

AIS is invaluable, but it only shows vessels that transmit. Radar shows everything else — fishing boats with AIS switched off, steel yachts, unlit craft, land, squalls and obstacles. Offshore or in poor visibility, AIS and radar complement each other rather than replace one another.

2. How much power does a modern radar use?

Solid‑state Doppler radars typically draw 20–40W in transmit and just a few watts in standby. They wake instantly, so you can leave them in low‑power mode and bring them up the moment visibility deteriorates. For solar‑reliant cruisers, this is a major improvement over older magnetron units.

3. Where’s the best place to mount a radar on a sailboat?

A mast mount (15–20ft above deck) gives the best range, but performance suffers when the boat heels unless you use a self‑levelling bracket. A stern gantry is easier to install and service, though you must avoid creating blind sectors with solar panels or wind generators.

4. What’s the difference between broadband, pulse and Doppler radar?

Broadband FMCW radar was the first low‑power solid‑state option, but it’s now legacy technology. Modern radars use pulse‑compression with Doppler processing, which gives far better short‑range clarity, instant target colouring and improved collision‑avoidance. Magnetron pulse radar is now largely obsolete on small yachts.

5. Can radar really detect rain and squalls?

Yes. Most modern units include a Rain Mode that distinguishes precipitation from solid targets. Offshore, radar will often spot squalls long before you can see them — especially at night — giving you time to alter course or prepare for the gust front.