"Stupid" question - Transducers...

[CntrySngr]

Okay, so this is probably a stupid question, but I am just curious to know how exactly this works.<br /><br />I am considering a Fishfinder/GPS combo, or even a stand alone Fishfinder. I read the manual for the Lowrance 332C (not all of it, mainly installation and usage) and I am a bit confused about something. With the Transducer mounted on the Transom, doesn't the sonar point towards the back of the boat? If so, then the fish that I will see in there are at the back, correct?<br /><br />Also, if this is the case, then what good is having the depth finder? By the time you see you are in shallow water, its behind you!<br /><br />Now if I am off, and the sonar goes to the front, then I apologize for the stupid question.<br /><br />One more thing...Lets say that I get the above mentioned unit and it has a 200KHZ transducer with a 20 degree "spread". The fishfinder screen shows an area of fish...where exactly ARE they?<br /><br />Sorry for stupid questions, but this is all new to me and I don't want to waste money on something if I don't know how to use it!!

 

[RatherBFishing]

Re: "Stupid" question - Transducers...

With the transducer mounted on the transom, you are somewhat correct that the view originates from the back of the boat, however transducers have an angle of view so you are seeing more than just below the boat, as you say. Some transducers also have side view and I would imagine thet probably have other views like maybe front.<br /><br />The do have transducers that can be mounted through the hull. I don't think that would really buy you that much more forward view.<br /><br />One important thing to note: Do not rely just on your sonar to determine your depth if you are concerned about hitting the bottom or objects. Most sonar have a delay and if you are running at a high rate of speed you will have hit the structure before you see it on your sonar. The old flashers work better for that, but the best thing would be to know the area you are boating in.<br /><br />Good Luck,<br />Mike

 

[CntrySngr]

Re: "Stupid" question - Transducers...

That's why I am considering doing a combo with GPS...if I do I will purchase the detailed area maps so that I can watch for depth in those as well. Most of the areas I will be in are pretty deep though. There are a few logs sticking out of the water, I'm concerned about those I can't see though! <br /><br />So, lets say I am anchored and the finder is showing me a bunch of fish in the area. These fish will be towards the stern of the boat, correct?

 

[cbcrawford]

Re: "Stupid" question - Transducers...

In using a "fishfinder" you aren't really chasing the fish you see on the screen. Better titles for these units would be "structure finder", "baitfish finder", or even the more accurate depth finder.<br /><br />You will probably NEVER catch a fish that you see on your depth finder, even if you can pinpoint the exact position of it. That is not how you use these units to succesfuly catch fish. You find an AREA that holds "fishy" structure, a few moving arcs across your screen confirm the presence of fish and their depth. You use the sonar to locate balls of baitfish that will attract predator fish.<br /><br />Sonar is more useful to identify structure, bottom types, and likely spots. And don't forget that it can;t tell the difference between a floating stick, clump of weeds, or a fish, so turn off the FISH ID function, don;t waste your time looking for individual fish, and find the type of structure and bait instead, you'll find that you will be far more succesful that way.<br /><br />PS - neither a depth finder nor a map will save you from a log or stump - keep your eyes open and your vest on when the big motor's running!

 

[demsvmejm]

Re: "Stupid" question - Transducers...

I don't know about Indiana, but i'm sure there's something similar, but in MI we have a websit ewith really good detail of hazards, depths etc. In MI it is at Detail Maps <br /><br />The lakes I'm familiar with ar efairly accurately displayed here. A little investigating should turn up a website for Indiana. My wife works at Michigan State University Extension Office and she found it while doing some research at work.

 

[RatherBFishing]

Re: "Stupid" question - Transducers...

Ditto what SHO-Boat said. And thanks for the link to the maps David. In both Indiana and Michigan (and probably others) Sportsman's connection makes some pretty good map books of the more common lates along with fishing information for those lakes. I have them for the lakes I most commonly fish.<br /><br />I have a Lowrance LMS 320 GPS/Sonar on my boat. The built-in maps don't show contour, and there have been times that I have been boating on land according to the maps. You can't rely on the GPS for an exact location, but it is handy to match you up to your position on the paper map. Maybe the newer units are more accurate and show some of the contour. In general though, I am very happy with my Lowrance.

 

[Richard Petersen]

Re: "Stupid" question - Transducers...

Fish finders are truly only DEPTH indicators. They accuratly show the bottom. They assume anything above the bottom is a fish and put a fish symbol on it. I have hooked into a suspended school of baitfish made out of seaweed.-------------------I angled my transducer 30 degrees foward so I can see what is coming up next.

 

[stevens]

Re: "Stupid" question - Transducers...

If you really want to see ahead of the boat for what is coming up below, there are really only a few products that will do this; namely the Interphase Probe (see http://www.interphase-tech.com/probe.htm ) and the Echopilot (see http://www.pilotmarine.com/ ).<br /><br />

<br /><br />Both of these were made to see forward, ahead of the boat. Apparently, the Echopilot works in realtime, whereas the Interphase one is a bit slower to update its' picture. None of them are designed to show you fish, only bottom structures and other obstacles.<br /><br />Would be neat to have, but I still wouldn't go out without a a good map on both paper and gps.

 

[mattttt25]

Re: "Stupid" question - Transducers...

ever notice that all fish seen on a fishfinder are moving from the right to the left side of your boat? i always fish off the port side because of that.

 

[Buttanic]

Re: "Stupid" question - Transducers...

Think of the transducer spread as an upside down ice cream cone. The point of the cone is the transducer. Any fish or botton structure that would be inside the cone would show on the screen. Notice that the deeper the water the larger area the cone covers. If the water is deep enough the cone could reach below the front of the boat at some point but there is no way to tell where in the cone a fish is, only how deep the fish is. If you know the angle of the spread of the cone you could calculate how large an area the cone covers at a particular depth.

 

[dingbat]

Re: "Stupid" question - Transducers...

You will probably NEVER catch a fish that you see on your depth finder, even if you can pinpoint the exact position of it. That is not how you use these units to succesfuly catch fish

I think you would have a hard time convincing those of us that spend literately hours staring at the FF looking to locate a school of fish in open water. A lot of these schools are so tight that plus or minus 5 feet can make all the difference between catching and fishing. <br /><br />It's also lots of fun to pass over a big fish while trolling and then pick out the rod in the spread that is fishing that depth and then proceed to count down to the strike. There is no way you could make this prediction unless you know exactly where the fish is and exactly where you’re baits are in relation to that fish.

 

[dingbat]

Re: "Stupid" question - Transducers...

Fish finders are truly only DEPTH indicators. They accuratly show the bottom. They assume anything above the bottom is a fish and put a fish symbol on it. I have hooked into a suspended school of baitfish made out of seaweed

Turn off the fish ID and learn how to interrupt the returns yourself. A patch of seaweed bares no resemblance to a school of fish when looking at the raw sonar returns. Once you learn how to read the returns you can even determine what species of fish you’re looking at.

 

[Moody Blue]

Re: "Stupid" question - Transducers...

Buttanic is right on in his description. Most people think that the fishfinder covers a large area under the boat. Wrong. Ultrasound from the transducer radiates out perpendicular to the transducer face in a conical pattern. Assuming you use a typical 20* transducer here is the optimal circular area you are seeing. 42" @ 10ft, 84" @ 20ft, 169" @ 40ft etc. These are not realistic because the power of the ultrasound diminishes rapidly towards the outer limits (perimeter) of the cone so in reality you are seeing a smaller area.<br /><br />Cyclops2 when you angle the transducers forward at 30* you have to be aware that the depth indicated on the finder is no longer accurate. While the finder will be showing 7ft, you infact only have 6ft of water. The other thing to be aware of is you will loose a fair bit of sensitivity because some of the ultrasound is deflected away off the bottom rather than being directed back up to the transducer. Think of throwing a rubber ball at a wall. If you throw it straight at the wall it will return straight back to you. If you throw it at a slight angle it will still return in your general direction but be deflected away from you.<br /><br />As others have stated, don't rely on the finder to warn you of impending shallow water or underwater obstacles. It doesn't matter if the transducer is mounted in the front or rear of the boat. Lets assume you have a 20ft boat with the transducer mounted at the bow and you are travelling at 30mph. Thats 44 ft/second. Lets also assume you are in 20ft of water so the angle of view that the finder sees is a 7ft cirlce on the bottom. Therefore the finder is "looking" out in front of the boat by 3 1/2ft. Suddenly a rock shelf juts up just below the surface. By the time you "see" the depth change on the finder you will have only 1/2 second to react before your outdrive slams into the rocks. Get and use charts if boating in unfamiliar waters or you takes your chances.

 

[CntrySngr]

Re: "Stupid" question - Transducers...

This information leads me to rethink my GPS/FF combo. I could go with a good FF and just use detailed maps of the lakes I fish and be better off. Plus, that would save me some $$$, which pleases the family!

 

[txswinner]

Re: "Stupid" question - Transducers...

down in Texas we tie a rock on a rope and drop it over for depth and a stick of dyno works best in finding fish!! Seriously Country the transducer must be in a location that has solid contact with the water. A transducer in the bow would not work well when boat is on plane. Good luck. Now back to my p-roe.