Someone please explain/ FF GPS questions

Ok, I just want to be sure I am thinking right. On a fishfinder, the watt output (RMS) is the important number as far as accuracy.....right? Does the resolution of the unit in conjunction with the RMS matter? For example, on a lot of models I've been looking at, the lower end units have higher RMS, but lower resolution where the next step up will have lower RMS with higher resolution. Would this mean the lower priced unit is actually the better one? Also, is an external GPS receiver really all that much of an advantage over internal...and why? I know, seems like a lot of questions. But I am looking for a combo GPS/FF and want to get the best for my money. I think I have decided to get a Humminbird because eventually I plan to add a SI and want something I can share memory cards between. But for now I need something good at a decent price for my console as the one I have has finally given up the ghost. It was a cheap HB that came with my boat and was pretty reliable, so I'm sure an upgrade will be even better. Help please!!!

Higher power improves the fishfinder's ability to see small objects. I wouldn't pay much attention to power unless you are comparing two units from the same manufacturer. There is no standard for measuring it, and it can be hard to tell what the numbers mean.

Higher pixel count improves the fishfinder's ability to display small objects. High power is useless without the pixels to benefit from it.

Even moderate cost units can show a crappie jig in the water, so it isn't that big a deal.

Choosing the Proper Fishing Sonar

SpeckWick,
You have to remember that these lower end fish finders are sort of dual purpose. (That doesn't mean there is anything wrong with them. On the contrary, they are usually pretty tough little units.) They are geared toward the occasional fisherman who also wants to use it as a depth finder. The higher RMS (if I remember correctly) will give you a quicker, more accurate depth reading at cruising speeds. I know a lot of people here on Kentucky Lake that use them on their ski boats because every now and then they like to wet a hook but their primary use is for depth reading. Also, if your lake is somewhat a shallow lake (say 1-50 feet) you usually don't need a very powerful unit and the high resolution will help you on target seperation on your display.

As far as an external antenna, let me give you something to think about. On my boat, I have an external antenna mounted right above my sidescan transducer. One reason is so that when I mark something on my screen as a waypoint, there is no built in error of 10 feet. If your unit is mounted 10 feet away from your transducer and you are using your internal antenna and you mark something on your screen, you have added a 10 foot error to your waypoint. Also an external antenna will help your reception considerably because your body and boat parts won't be blocking the signal in any way. Do you have to have an external...No, but there are advantages.

Now, I own Lowrance units and I'm not knocking HB but I can use my external antennas on any of my units by way of NMEA 2K cables and share waypoints. I'm sure HB has something of the same sort so you could network your units and you could share your antenna and you wouldn't have to be moving your memory card around unless you are using it with a preloaded map. Please don't misinterpret this as me downing Hummingbirds. I just don't know much about them. Hope this answers some of your questions.

Thanks guys. Also thanks Joby @ Humminbird for the pm. I think I am going with the HB 768. It has high resolution and power output. Plus I believe it has an external antenna. Sixfin, I understand your point about the location of the antenna over the transducer. Makes perfect sense, and for crappie fishing submerged brush that would be extremely important. I wasn't planning to buy anything truly "low end", just less expensive than a SI for now. I plan on mounting the new unit on my console since that one is dead right now. Once I finally step up to a SI, I plan on either moving the 768 to the front or putting the SI up front, but that's at least gonna be later in the year. Good thing is the 768 is networkable with the SI. That's really what made my decision for me. Less changes to make later. Again, thanks for all the help. I'll probably be back asking for advice on installation in a couple weeks, lol.

We're out in the cold when it comes to meaningful ways to tell what is good or not in the fish finder world. Obfuscation and BS seem to be the order of the day when it comes to what manufacturers think we need to know.

256 Color TFT Screen, 300 Watts RMS, 2000 Watts (peak-to-peak) 200Khz/20 degrees @ -10db

What the hell is all that supposed to mean? I know, but knowing doesn't tell me a darn thing about how well this particular fish finder will work for my way of fishing.

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Originally Posted by Fishtaco

We're out in the cold when it comes to meaningful ways to tell what is good or not in the fish finder world. Obfuscation and BS seem to be the order of the day when it comes to what manufacturers think we need to know.

256 Color TFT Screen, 300 Watts RMS, 2000 Watts (peak-to-peak) 200Khz/20 degrees @ -10db

What the hell is all that supposed to mean? I know, but knowing doesn't tell me a darn thing about how well this particular fish finder will work for my way of fishing.

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:D:D:D

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Originally Posted by Fishtaco

We're out in the cold when it comes to meaningful ways to tell what is good or not in the fish finder world. Obfuscation and BS seem to be the order of the day when it comes to what manufacturers think we need to know.

256 Color TFT Screen, 300 Watts RMS, 2000 Watts (peak-to-peak) 200Khz/20 degrees @ -10db

What the hell is all that supposed to mean? I know, but knowing doesn't tell me a darn thing about how well this particular fish finder will work for my way of fishing.

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OK, I thought I was confident with my choice. You guys aren't helping me here.:D How 'bout I just buy the one with the highest BS numbers that I can afford and cross my fingers?:D;)

Sounds like a plan!

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Originally Posted by Fishtaco

256 Color TFT Screen, 300 Watts RMS, 2000 Watts (peak-to-peak) 200Khz/20 degrees @ -10db

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That's actually a pretty good technical description of the parameters, lacking only a pixel count and screen size. Giving both RMS and peak-to-peak power helps compare no matter how it's given by other manufacturers. Giving the parameters that they use to define cone angle also narrows it down. They are saying that at the edges of the cone, the signal strength is 1/10th as strong as it is at the center.

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Originally Posted by CatFan

That's actually a pretty good technical description of the parameters, lacking only a pixel count and screen size. Giving both RMS and peak-to-peak power helps compare no matter how it's given by other manufacturers. Giving the parameters that they use to define cone angle also narrows it down. They are saying that at the edges of the cone, the signal strength is 1/10th as strong as it is at the center.

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I learn something every day.....

Measuring at -10db you get more bang for your buck.

Here is a good beamwidth scale. On the left is the db labels. Changing the db rating actually changes the "cone angle". At -10db, the cone angle is greater than at -3db. DB is a logarithmic function and is not linear.

Mathematical trickery.:rolleyes: No standards.

Sure glad you cleared that up Tom--now I can go sit and watch it snow the rest of day---:D:D

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Originally Posted by rnvinc

I learn something every day.....

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As do we all! :)

Someohow that actually makes sense to me. I guess I haven't forotten everything I learned in school after all.

I should have said "effective cone angle", or "working cone angle". The physical cone angle is fixed based on the crystal characteristics.

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Originally Posted by SpeckWick

OK, I thought I was confident with my choice. You guys aren't helping me here.:D How 'bout I just buy the one with the highest BS numbers that I can afford and cross my fingers?:D;)

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Speck, on the contrary, I think you've done a good job of sorting the wheat from the chaff. The manufacturers, on the other hand, let their marketing department sit through a 3 hour slide show of how the product works and then attempt to sell us these things with no real idea of how WE -- the consumers, use them.

Where does this leave us? Well, doing exactly what you're doing. Asking questions and trying to understand how these meaningless terms make one machine better than another. The specs don't tell us a thing, I'm sorry if the truth hurts, but the specs are mostly useless.

You're on the right track as far as I'm concerned. I'm just disappointed that we're being treated like morons with all the double talk.

Get the one that seems to be the best for your money. There is a touch of usefulness in there, you just have to have master's in crapola to make heads or tails of it. Unfortunately, that degree is only offered in the school of hard knocks.

Good luck

They are, after all, salespeople. That's why sites like this are so great. You get opinions and expertise from FISHERMEN who have used the products, and from those who do understand all the technical BS enough to warn the rest of us. Most guys look at the pictures and the descriptions in the BPS catalog and buy the most expensive thing they can afford. I found that some of the expensive ones don't have all the features I want, and that some of the less expensive ones do. I started out wanting to buy something cheap with GPS just to get me through till I can save up money and buy one of the big boys. But heck, with the "cheap" ones running $300 plus it makes more sense to throw in a hundred or so bucks and get a much better unit. I'll take the leap at the end of the year for something with SI...or sooner if I can somehow squeak out a tourney win or two. Thanks again for all the advice.

Is there a "good" moderately Priced $400-$600 unit that the SI & DI can be added to later?