Raymarine C140w, C90w manual Dual range radar operation digital scanners only, Limitations

With experience, the approximate size of different objects can be determined by the relative size and brightness of the echoes.

You should bear in mind that the size of each on-screen target is affected by:

•The physical size of the reflecting object.

•The material from which the object is made. Metallic surfaces reflect signals better than non-metallic.

•Vertical objects such as cliffs reflect signals better than sloping objects such as sandbanks.

•High coastlines and mountainous coastal regions can be observed at longer radar ranges. Therefore, the first sight of land may be a mountain several miles inland from the coastline. Although the coastline may be much nearer, it may not appear on the radar until the vessel is closer to shore.

•Some targets, such as buoys and small boats, can be difficult to discern, because they do not present a consistent reflecting surface as they bob and toss about in the waves. Consequently, these echoes tend to fade and brighten and at times, to disappear momentarily.

•Buoys and small boats often resemble each other, but boats can often be distinguished by their motion.

Note: You will need heading and position data for full functionality of your radar. A fast heading sensor is also needed for operation of MARPA and can maximize the performance of radar/chart overlay.

9.5Dual range radar operation (digital scanners only)

Dual Range radar operation enables you to view two ranges at the same time, in separate windows.

Using your multifunction display and a digital radar scanner, you can view either a short or a long range image in separate radar windows. To allow this, Dual Range must be enabled in the Radar Setup Menu (MENU > Radar Setup > Scanner Setup).

The default setting is Long, which provides a standard scanner range. The Short setting provides a maximum range of three nautical miles. The Long range value cannot be less than the current Short range value. For example, if Short range is set to 3nm, Long range cannot be less than 3nm.

Limitations

•Dual Range operation is not available if MARPA is ON.

•You cannot acquire MARPA targets if Dual Range is enabled.

•Chart-sync and chart overlay are temporarily disabled when Dual Range is enabled.

Using Dual Range with SuperHD radar

When using the Short Dual Range option, a SuperHD radar operates in HD mode only. When using the Long Dual Range option, a SuperHD radar operates in SuperHD mode for all ranges:

Dual Range	Range covered	Operation
LONG	1/8nm to 72nm	SuperHD
SHORT	1/8nm to 1½nm	HD

Using radar 105