Fog is the one condition where every skipper suddenly discovers what their electronics are really worth. A radar sees where your eyes stop, and modern solid-state domes do it on a power budget that a sailboat’s batteries can actually live with. The Raymarine Quantum 2 is the one people ask about most, so here is what its numbers mean in practice, and what it still will not do for you.
Spec sheet, short version
- Range scales from 1/16 of a mile to 24 miles, minimum detection at 6 metres.
- 17 W transmitting, 7 W on standby, 2 W asleep, on 12 or 24 V.
- 5.6 kg, 541 mm across, so a single mast bracket carries it comfortably.
- Doppler colour coding plus 25 simultaneous ARPA or MARPA targets.
What Doppler actually changes on the screen
Doppler processing measures whether a contact is moving towards you or away from you, and the display colours it accordingly: red for approaching, green for outbound. Everything static stays neutral.
That sounds cosmetic until you have a screen full of returns in a busy anchorage at night. Without it you are plotting each echo over several sweeps to work out which ones matter. With it, the two contacts that need your attention are the two coloured ones, instantly. Target history trails add the recent track behind each moving contact, so you can read a trajectory rather than a position, which is what actually informs a manoeuvre.
Doppler is not a universal radar feature, incidentally. In the Raymarine range it sits on the Quantum 2 domes and the Cyclone open arrays, not on the simpler radomes.
The numbers, and what each one buys you
| Specification | Figure | Why it matters |
|---|---|---|
| Minimum range | 18 ft (6 m) | Usable inside a marina, not just offshore |
| Maximum range | 24 nm | Early warning on a coastal or channel passage |
| Transmit power | 20 W solid state | No magnetron, so no warm-up cycle |
| Consumption | 17 W / 7 W / 2 W | Transmit, standby and sleep on a battery bank |
| Beam width | 4.9° horizontal, 20° vertical | The vertical spread tolerates heel on a sailboat |
| Size and weight | 541 mm wide, 5.6 kg | Modest weight aloft, which matters more than most owners think |
Why twenty watts is the interesting number
Old pulse radars announced themselves with a warm-up countdown and a serious current draw. A solid-state dome does neither. Seven watts on standby means you can leave it ready rather than switching it off to save the batteries, and starting a transmission takes seconds rather than a magnetron warm-up.
That is the difference between a radar you use and a radar you own. Most collision risks develop faster than the time it takes to decide the situation has become bad enough to justify powering up. Anything that removes friction from switching it on is a genuine safety feature, not a convenience one.
What it does not do, and this part is not optional
A radar is an aid. Under the international collision regulations, Rule 5 requires a proper look-out at all times by sight and hearing and by all available means, and Rule 7 requires proper use of radar if it is fitted and working, including long-range scanning for early warning and systematic observation of what you detect. The same rule adds the line every skipper should have taped to the chart table: assumptions shall not be made on the basis of scanty information, especially scanty radar information.
Read that as a warning about Doppler colours too. A green target is opening right now, which is not the same as safe, and small wooden or fibreglass craft return very little. The screen supplements your eyes and ears; it does not replace either.
Fitting it to a boat that already has a mount
Raymarine has kept the bolt pattern consistent across its radome generations, so a Quantum 2 will usually drop onto a plate that already carried an earlier Raymarine dome, and an adapter cable exists so you may not have to pull new cable through the mast. Usually is doing some work in that sentence, so measure your existing plate before ordering rather than after.
Connection is either Wi-Fi to a compatible multifunction display or a wired network, with 10 m and 15 m power and data cables offered. Compatibility covers the recent Raymarine display families, and the dome carries a two-year warranty extending to three if you register it within 90 days of purchase.
One piece of advice that applies to any radar install: the work involves the mast or a dedicated pole, the boat’s DC system and often a network run through bulkheads. Unless you are genuinely competent with all three, have it fitted by a qualified marine electronics installer. A dome that comes loose aloft or a badly protected power feed is not a problem you want to discover at sea.
Is 24 miles of range actually useful on a small boat?
Rarely at full scale, because your antenna height limits what you can see over the horizon. It matters as headroom: the long scales pick up weather cells and coastlines, while the work of collision avoidance happens on the short ones.
Radar or AIS if I can only fit one?
They answer different questions. AIS tells you about vessels that are transmitting, with names and courses. Radar shows you everything that reflects, including the fishing boat with its transponder switched off and the unlit buoy. Most cruisers end up with both, and the radar is the one that works when the other boat is not playing along.
Does the Wi-Fi version avoid all cabling?
No. The data link can be wireless, but the dome still needs power, so a cable goes up the mast regardless.
Radar is one instrument among several, and it is at its best next to a chart plotter you know how to drive properly.
Updated August 2026. Specifications for the Raymarine Quantum 2 Q24D (ranges, transmit power, consumption, dimensions, beam width, target tracking, connectivity, warranty) are the manufacturer’s published figures consulted in August 2026 and may change with product revisions. Rules 5 and 7 refer to the International Regulations for Preventing Collisions at Sea. Safety equipment requirements and installation standards vary by country and by navigation category, so confirm them locally. This article is general information, not navigational or installation advice.