Pacemaker Fishing Forum

AbuMasgouf · Jan-07-14 10:12PM

When I bought my FF last year I never spent anytime learning the differences in the frequency of the signals for either the sonar or the down (scan) imaging. My FF (587ci HD DI Combo) has the following:
Down Imaging®
Sonar Coverage

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

DualBeam Plus™
Sonar Coverage

200 kHz / 28° @ -10db
455 kHz / 16° @ -10db

Depth: 350ft (DI)/600 ft.

I have three questions,
1) What is the main difference between the different frequencies and what does it really mean to me?
2) What should I keep the settings on most of the time?
3) How wide of an area do I see under my kayak, thus does it matter if my transducer is in the Bow or the Stern of my kayak?

I did a search online but a lot of the information gave me mixed signals, so I figured I'd ask more experienced folks and be able to follow-up with them for clarification. Thanks in advance for the edification

Ernie · Jan-07-14 10:25PM

Excellent post...anxious to see some comments. I am having a DSI unit installed on my boat this week.

T. · Jan-08-14 1:36AM

Lower freq=wider cone and less detail. Penetrates deeper.
Higher freq=narrower cone and better detail.

I mount my transducers to the front because I want to see what I will be passing over, not what I've already passed over.

Bruce · Jan-08-14 9:33AM

Not sure if it's correct, but I was told years ago that there is a 1:7 ratio for your finder cone. That is, if you are in 21 feet of water, you are looking at a 3 foot section of the bottom.

GregF · Jan-08-14 3:56PM

T is correct about the resolution for the different frequencies. In a kayak I would assume you won't be in terribly deep water. As far as the diameter of the section on the bottom goes, assuming it is an isosceles triangle:

16 deg at 20ft is about 5.5ft dia circle
28 deg at 20ft is about 10 ft dia circle
45 deg at 20ft is about 16 ft
75 deg at 20ft is about 31 ft

you can extrapolate for shallower or deeper depths. (75 deg at 10ft is about 15ft (1/2 the dia at 20ft)

I haven't played with my FF frequencies enough to know what the best general setting is. It would depend if you are trying to locate potential fishing areas (large search area) or specific features/fish (high res/smaller search area)

captmikestarrett · Jan-08-14 5:09PM

I have two lying machines on my boat. One that does a 200 khz with large cone. This one will mark fish left and right and will put a little L23 = left 23 feet down or a R23 = right 23 feet down.
In 8 feet of water it shows a 22 foot cone. Good for locating fish.
The second one is 400khz and has only small cone of scan. 8 feet of water shows 10 feet of bottom. But this one is very sensitive and can show much better detail. So good you see a catfish fart.

Both are mounted on the back and have high speed pickups. The 400khz blurs at 46 mph and the 200 khz at 54 mph.
If you set it up right the little number at the bottom left shows cone size at the bottom. Lowrance systems. My old Hummingbirds 4x and double wide had that too.

My buddy has the high end touch screen Lowrance with side scan and it can do all kinds of things except show cone width in downscan..

Capt Mike

Osprey · Jan-08-14 8:50PM

captmikestarrett wrote:
So good you see a catfish fart.
Capt Mike

I was wondering.... what color is a catfish fart?
The last fart of any kind I actually saw was a kind of greenish brown.

GregF · Jan-08-14 9:16PM

Is that what happens when you get old????!!!!! You can actually start seeing your farts???!!!! and they are greenish brownn???!!!!! Oh my GOD!!! Please let me die before that starts happening.

bigjeffie · Jan-08-14 11:28PM

Since I cant afford a unit, I consider fishfinders cheating. My friends that have them on their
Bass rockets seldom use them, aside from a general depth gauge. Even then, since they go ro the same spots all the time,, they are kind of just like fuzzy dice on a rearview

Ernie · Jan-09-14 2:04AM

The downscan unit saved out butts at CBBT. It was incredible to see the difference between that and a regular sonar. I rarely us it for bass or white perch fishing save for using it as a depth finder.

AbuMasgouf · Jan-25-14 3:31PM

Wow gents! Thanks for all the info I really appreciate it! For some reason I didn't get a notification on the responses (even though I subscribed) so I didn't see any of these until now.

I guess based on GregF 's diameter notations it wouldn't make a huge difference whether the FF is mounted on the bow or stern. What prompted my curiosity is the New Hobie models with the transducer mounts behind the seat.

Thanks again gents I'm sure others will also find this information useful.

Pacemaker Fishing Forum

#1 Jan-07-14 10:12PM

FF frequencies in sonar and down (scan) imaging

#2 Jan-07-14 10:25PM

Re: FF frequencies in sonar and down (scan) imaging

#3 Jan-08-14 1:36AM

Re: FF frequencies in sonar and down (scan) imaging

#4 Jan-08-14 9:33AM

Re: FF frequencies in sonar and down (scan) imaging

#5 Jan-08-14 3:56PM

Re: FF frequencies in sonar and down (scan) imaging

#6 Jan-08-14 5:09PM

Re: FF frequencies in sonar and down (scan) imaging

#7 Jan-08-14 8:50PM

Re: FF frequencies in sonar and down (scan) imaging

captmikestarrett wrote:

#8 Jan-08-14 9:16PM

Re: FF frequencies in sonar and down (scan) imaging

#9 Jan-08-14 11:28PM

Re: FF frequencies in sonar and down (scan) imaging

#10 Jan-09-14 2:04AM

Re: FF frequencies in sonar and down (scan) imaging

#11 Jan-25-14 3:31PM

Re: FF frequencies in sonar and down (scan) imaging

Board footer