9/16" Ship Auger Bit

A 9/16 ship auger bit is the drill bit arborists reach for when installing cabling and bracing hardware, because its single spur and open flute clear green, wet wood without binding. The 9/16 inch size is a common match for 1/2 inch threaded rod and eye bolts.

Why a ship auger for tree work

Green wood is wet, stringy, and heavy, and standard twist bits pack up and bind. A ship auger has a single cutting spur and a wide, open flute that lifts chips out of a deep hole, so you can drill through a stem for a through-bolt or a dynamic anchor without constantly backing out.

Sizing the bit just over the rod diameter, such as 9/16 inch for 1/2 inch rod, gives a snug fit that still lets the hardware go in without forcing it. Check the hardware maker's instructions for the hole size they specify. Our cabling and bracing section has the rod, eyes, and cable to go with it.

Drilling tips

Use a powerful drill with a side handle and a slow speed, and keep the bit straight so the hole lines up from one side of the stem to the other. Back out every so often to clear chips. Drilling aloft means managing torque on a lanyard, so set your position well and keep both hands on the drill.

Keep the cutting spur sharp and dry the bit after use so it does not rust. Cabling and bracing should be planned and installed by trained arborists following ANSI A300 and Z133 practice.