Attract fish by sound, light or anything else

Why re-invent this particular wheel? There are commercial units available everywhere. Or you can try to build it yourself.

 

And I also agree that the title of the thread bears no resemblance to the homework topic, if the topic is how to build a depth meter.
You need to do a LOT of research about how to use acoustical methods to locate the depth of an object in water, i.e., commonly known as active sonar.
Come back here when you have something to talk about, or you find something you don't understand. We will try to help if we see you are trying to help yourself.

 

dynamite 'em

 

Try bait!

 

[SillyMode]
It might be easier to repel fish. A loud audio signal might do it.

Put concentric rings of transducers around the area you want to attract fish to. Activate the outer ring first, pushing all of the fish toward the center. Then, activate inner more rings in sequence. Then all the fish will be where you want them!
[/SillyMode]

Bob

 

2 inch "hook" works for me.

 

This thread is going nowhere. So howsabout a little out-of-the-box suggestion: mount a water-proof loudspeaker slightly underwater on the side of the boat. Play some fish-attractive sounds through it. Maybe try recording "Here, fishy! Fishy, fishy, fishy!" Search the Internet for fish-attracting sound clips. Report back here with pictures of results (species, length, weight) along with a "fish story" of how well it worked for you.

 

While not claiming any expertise in the 'fish-calling' field, wouldn't any sound transmitted into their environment more likely scare the fish off?
The vibrations may be interpreted by the fish as an approaching predator, or alarm 'clicks' of the school.
There are artificial lures that pop or rattle when trolled at medium to high speed, to hopefully grab the predator fishes' attention, but also simulates a fish / frog / insect in distress.
From wildlife / fishing documentaries seen on DSTV, a light source at night or dusk / dawn seems to work quite well.

 

Traditional fish aggregating devices (FAD) are silent floating platforms of various sizes. They usually don't have any active devices on board.Perhaps tossing it out there to float is enough.