Side scan vs. Down Imaging

[Pinch]

Which is better for looking at structure?

[Yakfisher]

Why not have both?

http://store.humminbird.com/products...88ab89389ddc08



What about forward scanning? It's great for finding structure and schools of fish.

http://www.interphase-tech.com/interphase/sonars.htm

[jffoley]

My view is that down imaging is an enhanced view of a traditional FF image below the boat. Side scanning gives you the ability to see structure "over there". Either left or right up to 240 feet!

I have the earlier 798ci model with only SI and the images are fantastic. You would really like it around the BB. The current 798ci Humminbirds have both SI & DI:

http://store.humminbird.com/products...ci_HD_SI_Combo

I can upgrade my earlier model to include DI. Hope that helps.

[Southerly]

i have the 798 ci si. it's not the HD model and i don't need the interconnectability of that model. ci means combo with gps antenna inside. si means side image. the letters HD was added for marketing but no performance change. just port for interconnecting to other units. check out the humminbird forum and the unofficial humminbird forum for your own clarification.

side image also spots fish and can tell you which side a school is mostly towards. it can spot fish that aren't under the boat but you will have to learn to trust the display. it makes dots, lines, bright spots/shadows, but not arches. you set how far to the sides you are looking. for example - in 20' water, 50-75' range will allow you to see fish that far out if it's dead flat calm and you're moving in a straight line. the wider the range, the more compacted all that displayed bottom must be. kayak speed is optimum for side image tech.

i posted some images on the recent ff install thread. range was set at 68'. you can see the school in side images. if you don't understand how to read the side image display, download the 798's owner's manual pdf. it has a good explanation. i'm using a modified wet well mount like jffoley posted last summer.

my unit includes down image and regular sonar. i'm 90% sure jffoley can upgrade his to include it by downloading the software update from the humminbird site. i already updated my software from v5.4 to v5.8 and it's very easy. but it's best to reset custom settings back to factory defaults before uploading. dohhhhhh

BOE Marine has an excellent price on this unit and i can highly recommend Jim for service and knowledge that you can't find anywhere else. and we're lucky - he's on kent island.

you also want to pick up a navionics gold sd.

[jffoley]

Southerly/Gary,

What model Navionics did you get? I am confused regarding the various models. On their website Navionics does not list the Gold 16XG that covers the East Coast of the US. Which, is all I need. I understand the 1XG is the entire US including CA, Hawaii and Alaska. Which, I don't need. I've seen listings for 16XG on the web. Is this a legitimate Navionics Gold product?

My research indicates the FishN' Chip is a lesser product and the Platinum is way overkill. Appreciate any input.

BTW, I did send a message to Navionics just yesterday about this but no reply as yet.

[Yak Fish]

Southerly/Gary,

What model Navionics did you get? I am confused regarding the various models. On their website Navionics does not list the Gold 16XG that covers the East Coast of the US. Which, is all I need. I understand the 1XG is the entire US including CA, Hawaii and Alaska. Which, I don't need. I've seen listings for 16XG on the web. Is this a legitimate Navionics Gold product?

My research indicates the FishN' Chip is a lesser product and the Platinum is way overkill. Appreciate any input.

BTW, I did send a message to Navionics just yesterday about this but no reply as yet.

I have the down imaging only FF...just got it in January and I got the 1xg gold navionics. I didn't even know about the fish and chip until after I got it, but it's the same price and shows less area so it's gotta be more detail but maybe not. Maybe it's just me but it doesnt seem like navionics advertises exactly what they are selling very well. The 788 does not accept the platinum navioncs where the 798 will. It looks like the bathymetry could be pretty awesome with the platinum but it probably is way overkill.

As far as the down imaging is concerned, I've gotten very good images. The down imaging only unit has a higher frequency beam so it should, all things being equal, give a better down imaging display. However, I can say that sometimes you're still not sure what you are looking at which is where the side imaging would be pretty sweet. I really wish humminbird had a side imaging unit with the higher frequency beam because I probably would have made the decision to jump up to the SI version.

Also the beam for the DI beam is 76 degrees so you do get some pretty good coverage. The way that it displays on the screen looks like an enhanced image of a standard sonar beam but you see much more of the bottom. What I've found is that you can set the bottom range much higher than the depth and you will essentially get a view to the side to some extent. You can do the math to figure out how far a 76 degree beam shoots...I believe it's about 1.5x the water depth, so 60' floor coverage (30' to each side) in 40' of water. If you set the bottom range to 100' you will see the max extent of that beam. After that, the image becomes black where there are no returns. You can compare this to the side image and you will see it's the same image to one side of the boat up to that 30'.

[DOGFISH]

I have been looking into the DI and SI models from Humminbird. From what I understand, the DI/SI models only have a single frequency transducer. Not that it really matters that much as the bay is not that deep. However, the DI units seem to be clearer, at least to me. Maybe it is just the amber on black color. The gray color of the side scan/DI units does not seem as clear.

Correct me if I am wrong. It was explained to me as to imagine a spot light beam going out to the side and angled down to the bottom. That is what you see from side scan. So does that mean the depth and angle dictates how far out to the side you see? So how far out to the side are you seeing in 20' of water vs 30' of water. I was looking at one unit, which broke down the screen into three sectors or views, GPS, Side Scan and Down Scan, which actually looked like four views.

The most important thing that I have added is the Navionics Fish and Chip card. I don't need all the marina information, overhead view and fish eye view. I just need the contours and drop offs. If I am going along those contours and have the DI, the only advantage of the SI seems to be possibly seeing which side of the kayak the fish are concentrated. Since I have added the Fish and Chip card, I can follow those contours, drops and channels right to the map. Given the tide and I can pretty much tell where the fish will be, if they are there. That seems just as important as seeing the fish when you actually do go across them. How many times do you hook fish that you don't see on the fish finder. I mostly look for fishy conditions and not actually the fish. I also have heard that Navionics is going to merge the fish and chip into their regular Gold card. They always have these cards at West Marine. Even when they do run out they resupply in a few days.

My question is, does the side scan really show that much? The demos are not really convincing. The DI alone units seem to be much higher definition.

For now that is why I am hanging my transducer of my old FF off the side of the new kayak, until I make up my mind about which new FF to buy. It seems that alot of the technology will come to one view eventually, which may not be that far off.

However, with all that said, I was at Bass Pro today and the 798 Ci SI DI, I think it was, will be on sale starting tomorrow, for I think the price was $795. I am not sure, but it was $700 and some odd dollars. For right now I am leaning towards the 385 Ci Di. Although, I might like a larger screen. Who knows?

[chex]

It seems that alot of the technology will come to one view eventually, which may not be that far off.

We went to the moon and 50 years later we're still looking at 2D guestimate images of what's under our yaks.... pitiful. It's about time someone came out with a 3D relative positioning system that remote controls our lures into the fish's mouth.

[DOGFISH]

We went to the moon and 50 years later we're still looking at 2D guestimate images of what's under our yaks.... pitiful. It's about time someone came out with a 3D relative positioning system that remote controls our lures into the fish's mouth.

+1

[medicyaker]

I'm still looking for a nav Chip that covers the BB. I have one that covers the lakes and the potomac but nothing anywhere near the BB. I'd like to keep it under $100 which is what I believe they sell for new, May be $200 actually. Chexone, you are right on brother!!! Can I use my same transducer from my 385ci with the new equivalant to the DI series?

[chex]

I'm still looking for a nav Chip that covers the BB. I have one that covers the lakes and the potomac but nothing anywhere near the BB. I'd like to keep it under $100 which is what I believe they sell for new, May be $200 actually

You have the fish n chip right? which one do you have that does not cover the BB?

[medicyaker]

Chexone, It says SD/16FISH Vol 19 on the card

[Southerly]

my sd card says 1xg all usa and bahamas on it. i agree re hard to tell what you're going to get with navionics. the fish n chips has lots more contour lines but doesn't have depth shading. i used the navionics compatibility link/chart, then googled the model number for price.

re fish n chips -more contours makes any sudden changes in depth more intuitive. the gold charts shading is for shallow/med/deep. blue/lt blue/white. i like that because i'm used to it with paper charts i suppose, but some might prefer the fish n chips.

the 798 has 455khz si, not 455/800khz option like the more expensive models in the lineup. presumably, the higher frequency would be able to achieve higher resolution. my specs says 2.5" target separation and i think that may be accurate. look at images i posted in the ff install thread. though i didn't post tree limbs, tree limbs look like tree limbs, etc so i'm happy. the di was added to the 798 as a software upgrade w/o adding an additional crystal to the ducer, but it seems fine to me. again, look at images i posted. i think this upgrade is largely a result of the head-to-head comp between humminbird and lowrance. and it's working like it should - consumers get the benefit!

ps - i have sharpness setting turned up to medium which makes it a little grainier, but easier to distinguish fish from background.

[chex]

Chexone, It says SD/16FISH Vol 19 on the card

Hmmm... 16 sounds like the code for the East Coast Gold maps. Add "FISH" to it and you get... navionics confusion. Strange that all of this is not clearer. I'd be happy with downloadable NOAA charts of the area, which I get on my iNavX iPad/iPhone app.

[Southerly]

re range setting and how far you see - i may be wrong, but i think when you set 50' ea side, that's what it shows no matter the depth. i think the unit is receiving more info but edits it down using its software to only display what you want to view.

keep in mind that an air bladder (my belief is that is what actually reflects) that is 50' away is going to seem very small, especially when displayed on 5" screen. you will be able to spot large objects far away and if that's what you're looking for, by all means, set the range wide. but if you're looking for individual fish, i don't think you'll notice them with a very wide range displayed.

the side image ping is like a thin slice of the water perpendicular to your boat. in my mind, like a digitized laser beam scan. a better explanation in the owner's manual pdf is available online.

455khz slices as you go along and add up to create the image on the display. if the boat is rolling due to waves, it's going to distort; especially things farther away. when you turn the boat, one side's slices become stretched apart, and the other side's slices become overlapped. again, the effect is more pronounced at farther distances from the ducer.

the kayak speed and generally decent sea conditions where i expect to yak most favor the si tech.

ps - x2 on standard noaa charts usability. they're free online, so why don't FF mfr's include that as a minimum?