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I'm starting to get a good idea of what I should be looking for when buying a fish finder. The new Bottom Line Tournament 480 Max has an 480x480 pixel screen, that is something that is good because it shows a big picture and good detail. When combined with 3200 watts of power I should be able to see just about ever fish on the bottom of the lake but the degree of the cone of the transducer is also important. A narrow cone is better for deep water and a wide cone is better for shallow lakes, some of you experts can correct me if I'm wrong so far. What I'm not so sure about is the RMS watts, I'm sure 400 is better than 200 but what does that RMS mean for me, as far as picking a good finder goes? Is RMS and frequency(kHz) the same thing? The last question is about FSTN, does that have something to do with the display? Thanks for any help you guys can give me. WH2
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Hey wh2, RMS is just another way of showing power, volts, etc, but not frequency. To convert peak to peak power, divide the peak to peak watts, and multiply by .707. Ie, 1000 watts peak to peak is 353.5 watts rms. RMS stands for root mean square, by the way. There is no difference between 1000 watts p-p and 353.5 rms.
As far as frequency goes, it seems like most fishfinders, at least the ones that I've looked at, are in the 200khz range. Two fishfinders in close proximity would probably interfere with each other, so I'm guessing that's why there are different freqencies available. Just like r/c airplanes and cars, you wouldn't want your signals crossing.
I have no idea what fstn stands for, sorry.
Mateo
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Oh, and to convert rms to peak to peak, just reverse the process. rms/.707=peak. peak * 2= peak to peak. Hope this helps.
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hi curt heres a thought why not look into a duel cone unit one that has a 20 and 60 degree cone both
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Some Finders list peak to peak and some list RMS, I understand how that works now. It makes sense about the Frequency but there must be more to it than just interference. On the Garmin 250, it is listed like this: 400 kHz(20*) and the Garmin 240 has 200kHz(20*). Thanks for the help Mateo. WH2
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Here's an excerpt from an article that explains it. I can't verify it's validity, but it's an explanation at any rate.
TRANSDUCER SELECTION
Look at various transducers and their features, they are the key to viewing with accuracy. The frequency determines effectiveness at given depths. Frequencies range from 50kHz to 455kHz. Deepwater models (600 to 1500 feet) operate at the lower frequencies while higher frequencies work better in shallow water (3 to 500 feet). More expensive models offer dual frequencies as features. A dual frequency unit gives the boater the best of both worlds. You get a narrow cone angle and good resolution of high frequencies and the depth penetration of the low frequency when needed. This combined with a split screen capability gives the ability to search out small targets like local structure and suspended fish at various levels.
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wiperhunter2,
I have an older BottomLine. My one complaint about it is the cone width. I feel that it is too narrow for the lakes in this area. I fished with it in a lot of different lakes around here, and therefore lots of different depths, and I always felt that it would have been better to have a wider cone. When in more shallow water, say 40 feet or less, the area being sampled is quite small so fish would have to be exactly under the transducer to be seen. What that really means is that your fish finder is really only reporting the distance to the bottom of the pond and rarely gives you an accurate idea about how many fish you are over, especaily if the fish are anywhere near the surface. The more shallow the water, the more true this is. So you have to ask yourself what kind of fishing do you do the most. I think a narrow cone would be useful in only the deepest of lakes, like Lake Powell and Flaming Gorge. If it were me, and I had to choose a single cone width, I would choose a wide cone width over the narrow width. As was mentioned, which cone width you need will help determine which frequncy is best to get. Also, a wide cone width will work even where a narrow cone width would be best, but it is harder to say that if things are reversed.
That is my experience and my advice, for what its worth. Good luck.
m
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Low frequencies travel through water great compared to high frequencies, however, you can't detect the detail with low frequencies that you can with high frequencies. The wattage available in fish finders nowadays is huge compared to what was available only a few years back. Wattage can be compared to volume. If you talk (low wattage) into a deep rock canyon, you may not here an echo at all. If you YELL (high wattage) into a deep rock canyon, you'll probably here a great echo. The old low wattage units needed to use low frequencies to detect objects at great depth. The poor detail was better then not being able to detect objects at all when using a higher frequency. The high wattage units available now days can detect stuff at great depths even with high frequencies. Nowadays I think the low frequency option is primarily useful if you plan on fishing deep oceanic trenches. However, there are probably other uses for low frequencies such as for penetrating very muddy water.
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Now, that makes sense, thanks RNL. I think I figured out what FSTN means, it must be the size of the screen that you are viewing because in one of the ads for Garmin it is listed as, 4.5" FSTN display.
Chris, I have a duel cone transducer on my finder right now and it works great at Willard but when fishing deep lakes, it just doesn't work the way I want. It looks like I need is a finder with more watts and frequency. What I'll be looking for is a finder that has at least 3200 watts PtP and a frequency of 400 kHz. What I need to check is the different cone angles that are available for the duel freq. I know they come with 20* but I wonder if they have angles smaller than that, say 7* or 9*, anyone know? WH2
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[left][size 5]FSTN[/size][/left]
Short for Film SuperTwist Nematic, FSTN is a type of LCD display.
found this on a geek board:
Many advances in TN LCDs have been produced. Super Twisted Nematic (STN) Liquid Crystal material offers a higher twist angle (>=200° vs. 90°) that provides higher contrast and a better viewing angle. However, one negative feature is the birefringence effect, which shifts the background color to yellow-green and the character color to blue. This background color can be changed to a gray by using a special filter.
The most recent advance has been the introduction of Film compensated Super Twisted Nematic (FSTN) displays. This adds a retardation film to the STN display that compensates for the color added by the birefringence effect. This allows a black and white display to be produced.
sm
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Wow SM, that is some interesting stuff, it almost makes it sound like it would be easier to have a color LCD than a black and white, but I know that could not be true. Thanks for the info.
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Wow, there is a lot of good information being discussed here. I also am looking at a new fish finder for my boat and the things being brought up will make me take another look at the technical end. As I mentioned in a previous posting, I am looking at the Humminbird Matrix 37 among others. This unit has 2-45 degree 455kHz beams that gives you a 90 degree view down to 160'. You can also use it in another mode that gives you two beams. A 20 degree beam at 200kHz and a 60 degree at 83 kHz, the latter is good down to 1,200'. You can also use all three configurations and do a split screen showing side-to-side and directly below. Where it is GPS ready, that feature will help in finding your way back to hundreds of "honey holes". I am still not sure what to do since a lot of people have had problems with Humminbird. I think I have narrowed to down to the Matrix 37, a Bottom Line and a Garmin. Decisions, decisions, decisions. Better hurry, soft water is on it's way. [:/][:|][  ][cool]
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Okay, I admit that I'm a dyed in the wool Lowrance fan, and therefore my opinion is biased. I have seen some fishfinders that work well, and others that wouldn't make a good anchor.
The worst performance that I've ever witnessed was a Hummingbird unit with a 455khz transmitter. It wouldn't show a 1/2 ounce jig with a 3 inch chub at 35 feet. Three guys at Fish Lake were marking splake at 35 feet, but couldn't use their fishfinder to lower their jig and minnow to that depth. They resorted to leaving the jig next to the hole and walking 35 feet away, letting their line out onto the ice. Then they had to walk back to the hole, and kick the jig in the hole. The line was stuck in the snow, and it was quite a laugh watching them fight the situation. Meanwhile, I would just lower my jig to the same depth as the splake, and never had to worry about the exact depth. Just put the jig at the same depth as the fish.
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thats pretty bad even my old fishin buddy 2 will show a 1" tube jig with a 1/64 oz jighead in 40' of water
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[reply]
[size 1]What I need to check is the different cone angles that are available for the duel freq. [/size]
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[font "Comic Sans MS"][size 3]WH2,[/size][/font]
[font "Comic Sans MS"][size 3]What is your reasoning for dual fequency? I really don't beieve you will need dual frequency sonar. The 200khz unit will do everything you'll need and want and costs a few buck cheaper. I've got the dual frequency 50/200khz Lowrance unit. The 20 deg, 200khz transducer for Utah fresh water lakes will do it all. [/size][/font]
[font "Comic Sans MS"][size 3]Dual frequency units cone with transducers with dual cone angles. Why? Because when you have the 50khz gong and shooting 1000+ feet down, you don't want to see half the bottom of the ocean that a 20 degree cone would give, That why 9 deg cones are standard for 50khz on the Lowrance units.[/size][/font]
[font "Comic Sans MS"][size 3]What you haven't talked about is vertical pixel count. This will be one of the most important features you can buy. This gives you the line seperation and detail you'll want when vertical jigging. Let's face it, that's where all this is needed. When trolling you don't need the line separation and detail when trolling. Ask IceFishingGod how he likes his X135 unit for jigging macks. It has 480 vertical pixels and the detail you can see, once you learn how to read it, is great. [/size][/font]
[font "Comic Sans MS"][size 3] If you are planning to spend your hard earned money, I suggest you take the time to visit each manufacturer's website and learn as much as you can. The Lowrance site has a lot of good information on all the info you are seeking. All the questions you have, are answered in layman's terms and are easy to understand.[/size][/font]
[font "Comic Sans MS"][size 3]Here's a good place to start.[/size][/font] [center][url "http://www.lowrance.com/Support/sonar.asp"]Lowarance Sonar's Learning Zone[/url][/center]
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I don't know what freqency mine is (probably 200khz), but my old humminbird wide eye will show my 1/32 oz jig. I just turn my gain up as high as it will go. I'm looking at the new humminbird 515,535, and 565 units. The have a sort of real time sonar window, which I would think would be similar to a vexilar for ice fishing, but probably not as good. The only reason I'm interested in a new one is because of the resolution and target separation.
I'm actually more confident in the humminbird than in other models. I know my humminbird works. I don't know about the lowrance or eagle, although I've read plenty of good things about them.
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BLM's comment on vertical pixels is good advice. Let's say you have two sonar units that are equal on all counts except the vertical pixels. Though not standard, for comparison purposes let's say one has 200 and the other has 600 vertical pixels (a 1 to 3 ratio). It's 100 feet to the bottom where you're fishing and the entire water column is covering your screen. That translates to 2 pixels/ft and 6 pixels/ft respectively. Though both units are receiving an equal echo of something suspended off the bottom, it's the software inside the unit that translates the echo to pixels. With equal software, 1 pixel on the low res' unit would be 3 on the high res' unit. An echo barely worthy of 1 pixel on the high res' unit will not light any pixels on the low res' unit because the echo is only 1/3 the strength needed to be worthy of lighting a pixel. Also, one line, two pixels thick, created by two stacked fish on the low res' unit would be two lines, each one pixel thick, separated by two to four blank lines on the high res' unit.
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I had a dual-freq transducer on my old Lowrance 350A and I ran it split screen showing both transducers all the time (when I didn't need the GPS showing in one half). Both views showed different details. But I didn't miss the feature when I sold that unit.
Another factor with vertical pixels is that the graph must have the processing power to be able to convert info from the transducer into those vertical pixels. A good way to determine the processing power is to look at the unit's scroll or ping rate.
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I think a lot of the problems people might have with some fishfinders is lack of power. My Humminbird Wide Eye that I now use strictly for ice fishing can track a tiny #10 rat finkie a long ways down. Once this year at Strawberry I was marking my lure and fish just a foot or so off the bottom in 55' of water. Now that is performance! When you are talking 4000 watts peak-to-peak (500 RMS)that gives you a good return signal on even the smallest object. My buddy bought a low-end Eagle unit for Ice fishing and he had problems picking up his lure, even in shallower water. Narrow cone angle can also hurt you if your are not very careful getting it aimed correctly, but it can help by giving you more accurate readings. The double edge sword thing. The dual angle transducers can help you in many cases. Like everything in life, there are advantages and di  vantages to just about everything.
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BLM, did you miss the statement I made in the original post?
"The new Bottom Line Tournament 480 Max has an 480x480 pixel screen, that is something that is good because it shows a big picture and good detail. When combined with 3200 watts of power I should be able to see just about every fish on the bottom of the lake"
My reasoning for dual frequency is that I fish two very different lakes, one that is deep(Bear lake) and one that is shallow(Willard). A 20* cone seems big because of the huge area that it will be covering in 80ft of water. RNL replied to the post by saying it would be better to have a 400kHz transducer for fishing places like Bear lake(or did I not understand what he was saying?) What I really want is a finder that works good for deep water and shallow water, is that possible?
The 480 max looks like the best finder for the price, it has a split screen and cost just $179.99. I need to do a little more research to find out what else it comes with but the only thing that compares for the value is the Matrix 27, it cost $249.99 WH2
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