What Furuno claim
According to Furuno, ‘the DRS4D-NXT packs the performance of an open-array radar in a compact 24in radome.’ That’s a bold claim, which they say is made possible by RezBoost, a digital beamsharpening algorithm which is said to effectively reduce the scanner’s natural 3.9° horizontal beam width to 2°. That’s not quite as good as the 1.85° from the 4ft array on our test boat, Alan Watson’s Nelson 42 Trinity Star, but is a big step closer. By comparison, the nominal beam width of Quantum is 4.9° from an 18in antenna.
Other key points are a new Target Analyzer, which uses the Doppler shift from other moving objects to help identify hazardous targets, painting them red while safe returns are green, and Fast Target Tracking, which automatically identifies and tracks other moving vessels to give you course, speed and closest point of approach (CPA) information.
Interestingly, the marketing claims do not mention close-quarters use, a key point of Raymarine’s Quantum marketing campaign. Our test started off at Alan’s berth in Hythe Marina. Setting each unit at minimum range, we compared the images obtained. All the scanners showed the T-shaped channel ( Trinity Star is moored on the vertical of the T), but the open-array and Furuno units showed a noticeable dead zone of about 20m radius, compared with 5m for the Quantum. Lateral resolution was sharper on the Furuno than the Quantum, but the elongated nature of the returns compared with the rounder blobs shown on the Quantum screen hinted that the Raymarine might have the edge on resolving targets on the same bearing at different ranges.
It’s interesting to note that, while the open-array and Quantum radars show the line of houses ahead as a solid return, the Furuno breaks them up slightly.