Fish Finder cone angles-technical question

Something to remember when talking about Cone Angles and depth finders sound wave patterns used for fishing.

[URL="http://i1084.photobucket.com/albums/j404/moveon100/depth%20finder%20How%20it%20works/fig123.jpg"]http://i1084.photobucket.com/albums/j404/moveon100/depth%20finder%20How%20it%20works/fig123.jpg[/URL]

[URL]http://i1084.photobucket.com/albums/j404/moveon100/depth%20finder%20How%20it%20works/fig11-1.jpg[/URL]


[QUOTE=peter;428668]There are a couple of very Knowledgeable guys that work in the fish finder dept at Bass pro in Clarksville. One is Cody and the other is on this site but can't recall his name at the moment. Maybe he will see this and chime in.

I spoke with with Cody last week about a transducer problem. He really knows the units. He has also fished with quite a few of the units.

Not saying one manu. is better than the other but I sent my unit back to Lowrance and and it took over 3 weeks to get one back. They did upgrade me to an hds unit for free so basically I got an hds 5x for $200 (price of the original unit). I have been on the phone with customer suport at Lowrance quite a bit lately and find their support to be very good.

As somebody suggested a back up unit is a real good idea.

I was inquiring about the cone angle on the newer units which is listed the same (20 degrees) as my vintage x70a but it seems to be much wider creating a much larger dead zone near the bottom when near steep banks.[/QUOTE]

That is the type info I was looking for. Sounds like you know something about it. The images are a little hard to read. Is it possible you can email me or make available a more readable image. [EMAIL="[email protected]"][email protected][/EMAIL]

... So if I want to target fish vertically (directly under the boat) in water 30-90 feet deep on a lake with a lot of bluff walls and steep banks for fish located on or near the bottom, near the bank, I would want the narrowest cone angle possible to reduce the dead zone? The dead zone on this HDS unit can frequently be from the bottom extending 20-30 feet upward so effectively I can't target fish in the situation described above. I don't remember that being the case with the old Lowrance x70a unit, both of which advertise the same degree of cone angle.

I am thinking that the new units being so much more powerful is part of the problem with the expanded cone? Alsothinking that maybe I need to get a lower power/less expensive unit. Lowrance does offer a 12 degree cone angle for the hds ($129), maybe that is worth a try? Additionally thinking "cone angle" is a very relative term and by itself does not mean that much?

Any ideas?

Thanks

you may find the articles below helpful.

[url]http://www.fishingtells.com/Articles/article-19.html[/url]

Thanks. I'll give it a read

Hi Peter:

I would not worry so much about trying to target the fish. Look for the structrure that fish hang around and then fish it. If you catch fish good if not move to another good looking structure.

But you are right in that a very narrow cone angle would work better on a steep sloping area. The disadvantage to this is that you would only be seeing a small area or slice of the slope at one time.

Basically Humminbird used a phased arrary type sonar beam in the past. This was before they came out with the side imaging Humminbird units.

Note: Sideimaging uses a very thin beam but moves it around from top to bottom very fast to make the sideimaging images.

Sorry about the image size and clarity. I copied them off a Magazine with my scanner. The size limits on the web site and the size limits with Photobucket make it harder to get really good big pictures that are clearer.

I tried to limit them to 800 pixels on each side. I'll try to work on this and see if I can make the images easier to read in the future.

Just note the Lobs of sound wave in the one diagram. That's bascially how sound travels though the water or air. They figure the dB and cone angles using trigonometry which is over my head. It's all about average sound levels and such.

I started out using the Lowrance Little Green Box back in the late 1960's and learned about sonar back then.

[QUOTE=peter;428693]That is the type info I was looking for. Sounds like you know something about it. The images are a little hard to read. Is it possible you can email me or make available a more readable image. [EMAIL="[email protected]"][email protected][/EMAIL]

... So if I want to target fish vertically (directly under the boat) in water 30-90 feet deep on a lake with a lot of bluff walls and steep banks for fish located on or near the bottom, near the bank, I would want the narrowest cone angle possible to reduce the dead zone? The dead zone on this HDS unit can frequently be from the bottom extending 20-30 feet upward so effectively I can't target fish in the situation described above. I don't remember that being the case with the old Lowrance x70a unit, both of which advertise the same degree of cone angle.

I am thinking that the new units being so much more powerful is part of the problem with the expanded cone? Alsothinking that maybe I need to get a lower power/less expensive unit. Lowrance does offer a 12 degree cone angle for the hds ($129), maybe that is worth a try? Additionally thinking "cone angle" is a very relative term and by itself does not mean that much?

Any ideas?

Thanks[/QUOTE]

Thanks again for the info.
Peter