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!

There are actually 4 sonar beams...
The 83 and the 200 are 2 separate frequency beams of the cone shaped 2/d sonar...
The 455 and the 800 are 2 separate frequency beams of the fan shaped DI...

Switchfire is a HB feature for the 2/d images..
Max mode allows all sonar echos to be shown... Can be very cluttered looking
Clear mode filters out some of the clutter...

Here is a depiction of the sonar beams in your unit...

http://i477.photobucket.com/albums/r...c/45c336a5.jpg

Because the DI beam is fan shaped and does not differentiate left and right (like SI can)...

There is no way to tell if an object showing on the DI screen is left or right of the boat... Only that the object is "somewhere" in that fan shaped DI sonar beam...

Rickie

okay thanks! that is such a wealth of info! thank you a ton!

Welcome from GEORGIA and good luck with your new finder.Thumbs Up

cary,
Go to You tube and type in HB 570, and you can see some good info. all kinds of film

If you look through some of these threads, there is a formula to figure out the area you are looking at. The cone ° x the depth, or some fraction x depth. It is not one to one.

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.