sonar problems

[Rick]

I have a garmin 240 finder and dont use the fish ID on it but instead of crisp arc shaped marks I get blots.It reads the bottom well and accuracy on depth isnt a problem.Any tips or reccomendations would be appreciated.

[SteveW]

I have noticed the same thing with that fishfinder. The arcs are more like arced blobs then the clearly defined arcs advertised or in the simulation mode. I have gotten used to them though and now can distinguish between fish and other things.

[steve1]

It actually could be a few different things. I've always heard that the only place you see arches is at McDonalds and Sport Shows! But you may try these things to see if it helps. Bump the gain up a few notches and see how that effects the definition of the fish. Another thing is to adjust your speed and see how that effects the return. In order to see an arch (the way you might expect from advertising) is to have all of the right things happen: fish in middle of cone, boat traveling at the right speed, fish traveling at the right speed. My 240 does a great job but every fish won't be a perfect arch.
hope the info helps!

Steve1

[chop]

I guess its just a marketing thing then,those little unmistakable arches that we all associate with being fish.I wish that garmin guy would put in his few cents worth that I see in here all the time.Ill try that adjustment with the gain settings too Steve.Thanks

[Walleye daddy]

I agree with the above posts: everything has to be just right to see a perfect arch. I have used mine for about 3 years and noticed that when conditions are just right, boat speed, fish in the cone, and gain adjusted a little higher, that you will see an arch. Usually smaller than whats advertised but it's there.I usually do see a mark or a faint arch when fish are down there. I 'm just used to it I guess. From what I've seen, most locators out there, usually simulate a nicer arch than what you really get when using the unit.

[Dodge1]

Check this out.

http://www.walleyecentral.com/takasaki/taka-electronics.shtml

[perchjerker]

Yes, what you are probably seeing are fish that are not going directly through the cone, just passing on the edge of it.

[REW]

Here is an idea to get familiar with your fish finder.

Go out into water that is 30-40 feet deep.
Take a small fish that you have caught - lets say a perch, sunnie, or crappie. Take about a 5 oz weight and tie on your line.

Tie a drop line several feet above the weight, and hook the fish to your dropper line.

As you drift in deep water - lower your "captive fish" over the edge of the boat. Have your rod on the upwind side of the "drift" so that the fish, will "swim" or "drift" under the cone of the transducer. You will find that you will easily see the fish - as some kind of mark on the depth finder - that is dfferent than the clear screen.

As you move along - you can change gain, settings, depth range, zoom -etc. as you raise and lower the weight - with its captive fish - so that you can see the effects of a "real fish" on the screen of your dpeth finder.

Since, you know the exact size of the fish, that you have tied to your line - you can gain knowledge - of what to expect in a real life "fishing" situation.

Spend a couple of hours doing this - learing how to interpret your depth finder at different depths, settings, etc. and you will be a much better fisherperson - on future outings.

p.s.
Make sure that - what ever fish that use as a captive fish - is duley caught and you have a licence to catch. It would be a shame to pick up a ticket from a warden - just as you are trying to advance your fishing education.

take care
REW

[bytemelitely]

This is how arches are made. Let say that your boat is stationary. Assume that a fish is 40 feet below the surface and enters the edge of the cone at 44 feet. The fish is detected at 44 feet, so a mark or indicator appears on the screen. The fish moves to a position 43 feet away, then42, then 41 and finally 40 feet, right below the transducer. Each successively decreasing distance is displayed on the screen in the form of a half arch. Now the fish continues to swim through the cone and exits on the opposite side. This creates the second half of the arch’s signature. Now look at the reality of the situation. First of all, the fish may swim up or down rather than at the same depth, creating more of an angled line or an upside-down J instead of an arch. The fish may just briefly cruise through the edge of the cone, creating only a few target points on the screen with minimal change in distances, so it appears as a short horizontal line. A fish is displayed, but no perfect arch.