Map chip worth buying?

I am new to lake Michigan fishing and have been gearing up for salmon. I've purchased the Humminbird 597 ci hd di but haven't had a chance to use it yet. It comes with basic charts that should allow the gps to be used for navigation and get me home in a fog. I understand that I can buy a Lakemaster chip with more detailed data for $150 . I am wondering if the enhanced info would really be helpful or really not necessary... I will be operating out of Milwaukee. Thanks in advance for any thoughts...

Okay. Having read comments I bought the chip. Dont know yet if more fish will be coming but wow, there is no question about needing to have the software. Incredible detail...

absafugginlutly get the chip

I have the same exact unit and I did buy the LakeMaster chip and it is well worth it. All of Lake Michigan is in 5 and 10 foot contours. Version 3 just came out at the beginning of April. I bought it directly off the website wwww.lakemap.com for $135 or so with tax and shipping. They should be $125 + tax in stores if they are out yet. Humminbird has a feature that allows you to adjust the map contour lines according to the lake level, so it will always be accurate. You can also highlight shallow water to your preferred depth as well as highlight a depth range. The website shows all of this information and more.