I just got a HumminBird 597ci HD DI Combo. It shot through the hull perfectly well in normal and DI modes - until the poorly installed puck got a leak. There will be no issue shooting through the hull with your Lowrance unit.
I did not check the temp accuracy against a regular thermometer. However, I have read that folks have found it to be pretty accurate.
Fish tremble when they hear my name
A ship in harbor is safe -- but that is not what ships are built for.
--John A. Shedd, Salt from My Attic, 1928