For Humminbird 740149-1 Gimbal Mount Kit, for Helix 8/9/10 Series Fish Finder
(1) Mark and drill four mounting screw holes using a 5/32” (4 mm) drill bit. 2) Place the mounting bracket, fill the mounting holes with marine-grade silicone sealant. 3) Place one flat washer onto each #10 x 1” wood screw.