Thread: Down Imaging Question

hi guys!

new guy here and first of want so say hello!

i am about to buy the Hb 570 Di but i have 2 questions about down imaging.

first off here are the sonar specs:


w/SwitchFire™
200 kHz / 25° @ -10db
455 kHz / 16° @ -10db

455 kHz / 75° @ -10db
800 kHz / 45° @ -10db

im guessing that the first set is min mode and the second set of 2 beams is max mode? mabye you guys can help me make sense of this.

here are the two questions:

1. how much of the bottom will i see with 2d sonar? im guessing a 1:1 ratio of depth to area on bottom covered right? and i underatand DI is a narrow fan shaped area perpendicular to your boat correct? in 30 foot of water how far off each side of the boat does the DI beam cover the bottom?

2. if i see a tree on the bottom on DI in 30 foot of water, how do i know where along the X amount of feet to the right and left of my boat it is on? can you even figure out which side it is on?


thanks for the help!

Sonar Beam Coverage Area

Below is a quick reference chart for the area covered by the specific cone angle listed. For example, if you are fishing in 10 feet of water and the cone angle on your transducer is 20 degrees, the area across the bottom is 3.5 feet.

• 20 degrees - 0.35 or roughly 1/3 of depth
• 24 degrees - 0.42 or roughly 2/5 of depth
• 30 degrees - 0.53 or roughly 1/2 of depth
• 40 degrees - 0.72 or roughly 3/4 of depth
• 50 degrees - 0.93 or roughly 9/10 of depth
• 60 degrees - 1.15 x depth
• 70 degrees - 1.4 x depth
• 73 degrees - 1.48 x depth
• 80 degrees - 1.68 x depth
• 90 degrees - 2 x depth
• 100 degrees - 2.38 x depth
• 110 degrees - 2.85 x depth

It is a trig function.