Bail Mounting the Device
If you are mounting the bracket on fiberglass with screws, it is recommended to use a countersink bit to drill a clearance counterbore through only the top gel-coat layer. This will help to avoid any cracking in the gel-coat layer when the screws are tightened.
The bail-mounting hardware (screws and washers or nuts, washers, and bolts) is not included. The holes on the bail-mount bracket are 5/16 in. (7.9 mm) in diameter. Before you can bail mount the device, you must choose mounting hardware that fits the holes in the bail-mount bracket and securely attaches it to your specific mounting surface. The size of the pilot hole required depends on the mounting hardware you choose.
You can bail mount only the eight-inch and 12-inch models. Due to the size of the 15-inch models, you must install them using the flush-mount or flat-mount method.