I assume you had a SHOOT-THRU with your Humminbird.
A thru-hull takes a 1"+ hole through the hull for the installation.
You can do the same with a Lowrance too. The shoot-thru puck is easier to install than the round transom transducer.http://lr.factoryoutletstore.com/details/14934/lowrance-106-89.html?category_id=20826
Humminbird Helix 12 CHIRP SI, 1198c SI, 1198c SI, ONIX 10 SI NT, Helix 7 CHIRP SI GPS G2, SOLIX 12 SI, 360, RC-1