CE Smith Boat Trailer Guide-Ons - Lighted Post-Style Lighted guide-on posts are boat trailer guides that make it easy to load your boat onto your trailer, as well as safer to transport your craft after dark. For durability and ease of use, CE Smith boat trailer guide-ons are the industrys best. Heres how they work As the trailer is backed down the ramp and is partially submerged, these 40 tall boat trailer guide-ons, which are mounted at the rear corners of the frame, remain above the water line