If you're staying at Springhill Suites downtown you won't be going through the Chickamauga Lock. That is a bit further up river.
Have fun, the Tennessee river gorge is some of the best scenery around and downtown Chattanooga is a blast. If you guys need any recommendations on where to go let me know. Do yourselves a favor and don't hit up any chains, there are way too many good local joints.
edit: Erwin Marine has their main location up river of the Chickamauga Lock but you will want to contact their downtown location for the docks at Springhill Suites. This will put you right on top of all the good night life.
https://www.erwinmarinesales.com/--city-of-chattanooga-marina