I don't know much about the Lowrance units but looks like you can get some good deals on this unit that include the navionics chip. Check out which lakes are available using their web app.
https://webapp.navionics.com/?lang=e...sm%7CxFj%7BpfM
With any type of imaging (down or side) the transducer is going to need to be in the water. Thru hull will distort the image quality. 2D sonar works fine thru hull. you won't get a temp reading if mounted inside the hull though.
Personally I have always been a Humminbird fan. The customer support is awesome and I have never had an issue with any of my 6 units over the years.
I just picked up a Helix 5 Chirp GPS G2 yesterday to be used for ice fishing, yak, and on the bow of boat. The helix line is feature rich and includes AutoChart live which makes your own contour map on the fly. It will let you find the spot on the spot. Autochart also maps bottom hardness and vegetation. I am excited to see how this works in real life. Based on the videos it looks like it could be a game changer.
Based on my internet research the Humminbird imaging is considered to be better than Lowrance. 2D sonar is a push with a slight edge to Lowrance. I haven't compared them personally though.
Humminbird is running a promo on the Helix 5 where you can get up to $50 rebate depending on the unit.
https://www.humminbird.com/promotions
Humminbird also has a transducer exchange program where you can swap out the included transom mount transducer for a thru hull or tm puck. You can use the transom mount transducer as a thru hull. Tons of vids on how to setup.
https://www.humminbird.com/support/f...sducerExchange
With how far technology has come any unit will meet your needs. It is all about the extra bells and whistles. Nice thing is they hold their value and you can always get most of your money back selling it on ebay.
