Need some advice here.I bought an 88 top gun in march.It does not have any electronics for navigation nor does it have a depth finder.I would like something that has gps, navigation & depth capabilities.I am sure there are more functions I will need but really do not know what.There are so many options on the market, it makes my head swim reading all the descriptions.Ease of use also is a big positive.Thanx for any advice.