The Sonar Viewer has been completely overhauled, with added support for side-scan sonar from Lowrance and Humminbird in a vertical, waterfall display:

• The button to open the sonar viewer has moved to the bottom of the window toolbar, at the left of the window (circled).
• Any combination of available channels can be viewed, by selecting from the channel buttons underneath the viewer. If a channel button is disabled, then that channel is not present in the sonar log file. The relative sizes of the channel displays can be adjusted by dragging the dividing bars.
• Click the Show Boat Position button to see the position of the current sonar display relative to the track. Note that this position relates to the far right of 2D channel views, and the top of the side-scan view.

Slant-range and gain adjustments



Slant-range adjustment is the process of removing the water column and stretching the remaining sonar image so that it is shown in a geographically accurate way. Slant-range adjustment tends to me more successful in flatter areas.
The automatic gain adjustment feature attempts to level out the signal return across the full sonar range, lightening the outer fringes of the display and darkening the centre. It is often possible to discern far more detail at the edges of the sonar image when the automatic gain correction is used.



To activate slant-range adjust and automatic gain, use either the right-click menu options in the sonar viewer, or the buttons in the sonar viewer settings toolbar.

Measuring objects and estimating object height

The measure distance tool now also works in any sonar channel display. The measure distance tool is activated using the button with the horizontal ruler, in the mouse-mode toolbar.

• In 2D channels (1, 2, DS), the measure distance tool measures the change in distance travelled as well as height.
• In the side-scan channel, the measure distance tool measures distance only.

Estimating object height
The length of the shadow that an object creates can be used to estimate the height of that object.
The measure height tool works only in side-scan channel displays, and is accessed by clicking the button with the vertical ruler in the mouse-mode toolbar.



To use the tool, click the object of interest and hold the left mouse button down whilst moving to the edge of the shadow. In the example above, the object is a tree stump in a sunken town. It is not necessary for the object to be on the bottom; for example, the height of an individual fish can be measured by measuring the distance between the fish's return and the shadow that it casts.

Waypoints and the Mouse Tracer

With the waypoint tool selected, waypoints can be dropped into any sonar channel. Waypoints dropped in 2D channels will be placed at the appropriate position along the track. Waypoints dropped in the side-scan channel will be located at the correct offset to the track.

Note that ReefMaster uses bearings calculated from the recorded positions within the track to determine the offsets used when calculating waypoint positions in the side-scan view. Significant inaccuracies in waypoint locations may result when this bearing does not tally well with the orientation of the boat and/or side-scan transducer. This effect may be more pronounced when running at slower speeds or significant wind or tide. You should never rely on waypoints made in this way for navigation.

• To drop a waypoint in the sonar viewer, select the Drop Waypoint mouse mode, and click anywhere within a sonar channel display with the left mouse button. Note that waypoints themselves are not shown within the sonar display.

The Mouse Tracer
The Mouse Tracer is a tool that shows the current position of the mouse in all other open editing windows. The mouse position is shown as a small circle. The tracer works from any geographical editing window to any other, and from any sonar channel display to any geographical window. This tool can be useful for helping to visualise the location of underwater objects in the side-scan display, or cross-referencing the position of objects across multiple tracks (to display multiple tracks at the same time, rearrange the track windows within the ReefMaster workspace by dragging their tab headers).

• To activate the mouse tracer tool, click the Tracer button in the application status bar.