Raymarine DSM300 User Manual

Also see for DSM300: Installation manual Install guide

Contents

Raymarine DSM300 User Manual Manual pdf 64 page image

64 DSM300 Operation with PLUS Series Displays5.2 Interpreting and Adjusting the Sounder ImageThe DSM300 uses sound waves to find fish and show bottom structure. Thetransducer sends high-frequency sound waves into the water; these sound wavesstrike fish, the bottom, or other objects in the water and return as echoes. TheDSM300 interprets these echoes to present an image of the fish and bottom.The strength of echoes is indicated by different colors (or shades of gray inmonochrome displays). You can use this information to determine the size of fishand the bottom structure. Other objects in the water, such as debris and airbubbles, also return echoes; these echoes are generally weaker than the fish orbottom echoes and produce background noise or clutter on the display.The digital sounder provides controls to reduce the background noise and toadjust the way in which echoes of different strengths are displayed. The colordisplays also let you select the background color and remove the display colors forweaker echoes.The sounder provides a White Line feature which helps to distinguish between thebottom and fish (or other objects such as weed) that are close to the bottom.Target IndicationsWhen the sounder detects a target echo such as a fish, it displays a representativeimage on the LCD. The shape and size of this image is influenced by a combinationof factors:Boat speedThe shape of the target changes along with your speed. Slower speeds returnflatter, more horizontal images. As your boat’s speed increases, the image willtend to thicken and arch slightly.The depth of the targetThe closer the target to the surface the larger the image on screen.To display the depth of individual targets, switch on the TARGET DEPTH ID fromthe menu, as described on page 44.The size of the targetThe larger the target, the larger the return on the fishfinder display. The size of afish target is however dependent upon the size of the fish’s swim bladder ratherthan its overall size. This swim bladder will vary in size between different breeds offish.