I have found using Navionics Sonar Charts has made the biggest difference on my fishing during the summer months when the fish move out deeper I can pay attention to my charts to find those drop offs near the channels. I have found using the Navionics Free Web App you can view the SonarChart as well as get it on your phone as well. If you purchase the Navionics + platinum or update for your Chartplotter you will gain the Sonar Chart feature.
I fished lake Jordan for the first time today only for like 4 hours though. Right off the bat I caught a one like 2lb on a football head jig in 10ft of water. We wanted to find some off shore structure using his electronics it was kinda hard because he didn't have a very good map in his unit. So I pulled my Navionics App up on my Iphone and we used that one thing I did right off the get go was adjust the water level feature on my app, he said the lake was down 3 feet so I typed in -3 feet and the map adjusted the contours to -3 feet pretty cool. We ended up finding some good structure out deep and we starting throwing deep diving crankbaits on the structure we lost two fish over five pounds. I will defently will be making a trip back down to the the lake soon.
If you have a Lowrance HDS Gen 1 or 2 you can do sonar logging on your unit. So if there is a body of water that you would like more detail on you can go out and record while your fishingfor Navionics SonarChart program. Navionics just came out with a list of all the units that can record and instruction on how to do it as well. They accept multiple different formats of sonar logs. To see more on SonarCharting or want to know how to do sonar logging on your Lowrance, Raymarine, Humminbird, Simrad, and B&G visit www.navionics.com/sonarcharts Navionics now accepts multiple formats of sonar logs as contributions to SonarCharts. This includes Humminbird (DAT and GPX on all models, ION and Onix compatible within summer), Lowrance (GPX), Raymarine (SDF, GPX, NMEA), Simrad (GPX), and Garmin (ADM). Here is a quick video on how to do it on a Lowrance HDS Touch.
I was fishing last week on Wednesday it was so hot and I new the fish would be out deeper hanging to the break lines and transition points. So I was out in 24 feet of water paying close attention to my Navionics Chart on my Lowrance HDS and i'm noticing on my Chart at the end of the point it went from 20 -25 in about 2 feet so I casted my Carolina Rig over there and cracked into a big fish a 7 1/2 pound bass.
I was reading on some other blogs couple of weeks ago about the Navionics Update how its for people that have a older Navionics card and want the latest Data. So I purchased the the Nav Update it was $99 for a year with free updates for a year as well. Its actually a brand new card you get and you download the information onto to card. I tell you what there is a huge difference between my 4 year old card and my new one so many more contours. I like studying a map in my free time of lakes and rivers and I know this update will make a difference on how many fish I catch during the summer months.