Transducer cone

[Ranger375]

I have seen it somewhere and if I good remember back 100 years i could figure it out. If your transducer has a cone angle of say 20 degrees how do you figure out how large a circle you are looking at in say 20 feet of water.

I know it can be figured out with simple trigonometry, but that has been to long ago.

[papasage]

i called hummingbird one time and they told me but i cant remember . you could the mfg. of the finder and they could tell you

[papasage]

i called hummingbird one time and they told me but i cant remember . you could the mfg. of the finder and they could tell you

[bentpole]

good Question Ranger:Was looking at a BPS catalog tonight & wondering the same thing.Noticed there Matrix 37 had a 90 degree coverage.

[CrappiePappy]

I've always gone by this "math" -- a 20deg cone angle will show a circle that is 1/3 as wide as the depth ......... or, in other words, in 21ft of water - the circle would be 7ft wide on the bottom of the lake. That's an "approximate" dimension, of course.

(Eagle's manual says a 20deg cone angle will show 2/5 as wide a circle as the depth ... or an 8ft circle in 20ft of water)

Take your pick ............ it's all pretty relative, anyway - the sound signal goes down as an ever expanding cone - hits a flat bottom as a circle - then the transducer picks up some of the returning signals - and the unit deciphers those signals and makes a 2 dimensional picture out of them. .......luck2ya .........cp

[crappieken]

Barry - The manual that came with my depthfinder shows that with a 20 degree cone angle you cover approximately 6 feet of bottom with a water depth of 15 feet. Since I no longer have my old trig book, I took that information and figured the tangent for a right triangle with the legs of the right angle being 15 feet and 3 feet. This would give you the figure of .200. Now, you can take your depth and multiply it by .200 and then double that figure to see how much bottom you are covering. If your depth is 20 feet, multiply 20 by .200 which gives you 4 and then double the 4 which gives you a coverage of 8 feet of bottom at 20 feet. If your depth is 30 feet multiply it by .200 which gives you 6 feet and double the 6 which gives you 12. So, at 30 feet you would be covering about 12 feet of bottom. I hope this is fairly accurate as I haven't worked a trig problem in 50 years.

[unknown 5]

My Fishing Buddy II has a sidefinder cone on it and it will pick up fish 80' away. I couldn't guess how big a cone it has. I do know that when I get multiple returns in an area, it is often a school of crappie.
The Hummingbird Matrix 17 has a 60 degree cone. The 37 has a 90 degree cone. I am not sure if the extra coverage is worth the extra money.

[Ranger375]

Now know why I don't have Crappie in front of my name not smart enough...LOL. Thanks crappiepappy and crappieken. I knew there was a simple formula somewhere but could not find it and of course could not remember it. I'll write it down so next year I won't be asking the same question.

Again thanks guys.

[crap-king]

Mama always said boy you going need that geometry and algebra some day - I just didn't know it was going to be so I could catch a fish
crap-king

[Moose1am]

Just remember that the 200 KH frequency is the 20 deg cone angle and the 1/3 rule for humminbirds and you will be fine.

Some of the humminbird unit's have multiple frequency transducer that send out different frequencys in different directions and they show the different results on the screen differently. Solid fish symbols for fish right under the boat and outlined fish symbols for fish to the side of the boat.

Humminbird has three different type of transducers that you can buy for the Matrix 37 unit.

The frequency of the transducer is determined by it's size. As the Transducer is nothing more than a solid crystal with some electrical lines attached to give juice to the crystal to make it vibrate. The entire crystal is covered with a plastic type material to protect it.

I read about this stuff somewhere in the past on a web site but can't remember where or I would post the link.

The there are some 60 deg cones and some even up to 90 deg. The distance the sideways scans go is determined by the sensitivity settings. The higher the gain is set the farther out the sonar will find objects in the water.

Now know why I don't have Crappie in front of my name not smart enough...LOL. Thanks crappiepappy and crappieken. I knew there was a simple formula somewhere but could not find it and of course could not remember it. I'll write it down so next year I won't be asking the same question.

Again thanks guys.