Ship Auger Bits: Standard vs Power Pole, Length, Self-Feed

What is a ship auger bit?

A ship auger bit is a wood-boring bit with one long spiral, one cutting edge, and a threaded screw point that pulls the bit into the wood. The name comes from shipyards, where carpenters bored long, straight holes through heavy timbers for through-bolts. Three details set it apart from other augers:

• No outer spur. A regular wood auger scores the edge of the hole with a spur. A ship auger skips the spur, so there is nothing fragile at the rim to snap on a nail.

• One open spiral. The single twist leaves a wide channel (the "deep throat") for chips, which is why the bit keeps cutting 15 or 30 in. down.

• A screw point. The bit feeds itself. Your job is to hold the drill and steer.

Tap any part of the bit to see what the words on the label mean.

From ITM's spec sheets for the 302SL, 303SL and Power Pole series.

Standard or Power Pole: which ship auger bit do I need?

Buy a Standard ship auger bit for framing lumber, posts and timbers, and a Power Pole ship auger bit for treated poles, railroad ties, bulkheads and pilings. The two share the same shape. The difference is the tip and the reach.

Verdict: Standard for framing, posts and anything inside a building. Power Pole for treated poles, railroad ties and pilings, for holes deeper than 15 in., or when the bit goes on an impact wrench.

Price is the honest tiebreaker. A 13/16 in. x 18 in. Power Pole costs $145.10 against $35.38 for the same size in Standard, about four times as much. In a pole that pays for itself: preserved pole wood is full of grit and chemistry that dulls plain steel fast. In clean framing lumber it buys you nothing. And because carbide is brittle, keep the Power Pole bit out of nail-embedded remodel framing. That is the Standard bit's job.

What length ship auger bit do I need?

You need a ship auger bit whose reach is at least 1 in. more than the wood is thick. Reach is the bit's overall length minus about 3 in. for the shank in the chuck, which is how ITM rates its Power Pole bits (an 18 in. bit drills 15 in. deep, a 36 in. bit drills 33 in.). The extra inch lets the screw point and cutter break all the way out the far side.

Stack up what you're boring through and the planner picks the shortest bit that clears it:

For a round pole or piling, measure across the pole where you'll drill, not at the butt. Poles taper, so the crossarm end is thinner than the ground line. If you can only reach halfway, drill from both sides with the same bit and meet in the middle.

When in doubt, go up to 18 in. In the same diameter an 18 in. Standard costs from nothing to $22 more than the 8 in. one (3/4 in.: $32.70 vs $27.61) and reaches three times as deep. The 8 in. bit earns its place where an 18 in. bit can't turn: between studs on a right-angle drill.

Here is what each step up in length costs, in two common sizes:

Prices from our catalog on Oct 29, 2026. A dash means that size isn't made in that length.

Long bits in short wood is a common mistake. A 36 in. bit through a 6x6 whips at the end of the drill and wanders. Use the shortest bit that reaches.

What size auger bit do I need for a bolt, pipe or cable?

For a bolt, use an auger bit 1/16 in. bigger than the bolt. For pipe, tube or conduit, use the next size up from the outside diameter, so the run slides through without binding. These are the sizes crews ask us for most:

CTS and EMT outside diameters are the standard trade dimensions. Stud limits from IRC R602.6 and NEC 300.4(A)(1); your inspector has the final word.

The last column is why size matters in a wall. In a load-bearing 2x4 wall, IRC R602.6 caps a bored hole at 40% of the stud's width, which is 1.4 in., with at least 5/8 in. of wood left at each edge. The electrical code adds its own rule: if the edge of the hole is closer than 1-1/4 in. to the face of the stud, cover it with a steel nail plate so a drywall screw can't reach the cable. In a 2x4, any centered hole over 1 in. needs the plate. In a 2x6, every size we sell clears it.

What does "self-feeding" mean, and is a self-feed bit the same thing?

"Self-feeding" means the screw point threads into the wood and pulls the bit forward on its own, so you don't push. A "self-feed bit" is something else: a short cup-shaped hole cutter, usually 1 to 4-5/8 in., that plumbers use for drain lines through joists. Both use a screw point. Only the ship auger has a long spiral and real reach.

The screw point changes how you drill:

• Low gear, steady trigger. High speed spins the cutter faster than the screw can feed, and the bit burns instead of cutting. Our drill speed chart explains why heat ruins bits.

• Brace the drill. When the screw bites a knot or the cutter grabs a nail, the bit stops and the drill keeps turning. Use the side handle, or a right-angle drill with a clutch, and stand where a spinning drill can't pin your hand against a stud.

• Back it out every few inches in wet wood. Treated lumber and green poles pack the flute with wet pulp. Pull the bit out while it's still turning, clear the chips, and go back in.

• Don't drill into an old hole. With nothing for the screw to grab, the bit stops feeding and only rubs.

For drain-size holes (2 in. and up) a ship auger is the wrong tool. Use a hole saw on an arbor instead.

Can I use a ship auger bit in an impact driver or impact wrench?

Use a Power Pole bit in an impact wrench, and a Standard bit in a 1/2 in. drill. ITM rates its Power Pole augers for 1/2 in. drills, impact wrenches and gas, air or hydraulic drill motors, which is how utility crews run them. Their 7/16 in. hex shank fits a 7/16 in. quick-change chuck. A Standard bit belongs in the 3-jaw chuck of a 1/2 in. drill or right-angle drill.

A 1/4 in. hex impact driver is the wrong tool for either one. The shank doesn't fit its chuck, and the driver doesn't have the steady torque a 1 in. auger needs 15 in. down.

Which ship auger bits do we stock, and what do they cost?

We stock 60 ITM ship auger bits: 28 Standard (8 in. and 18 in.) and 32 Power Pole (18 to 48 in.). Each one is sold individually.

The grid shows every diameter and length we carry. Switch the view to see price per inch of reach, the bolt each size clears, or whether it fits a load-bearing 2x4.

Prices and minimum orders from our catalog on Oct 29, 2026. Every bit is sold individually; sizes marked 2 have a two-bit minimum order. "Ships from maker" means we order it from ITM for you.

Shop by series: Standard ship augers or Power Pole ship augers, or see the whole ship auger collection.

Which three sizes should go in the truck first?

Start with 3/4 in., 7/8 in. and 1 in. Those three made up about three of every four Standard ship augers our customers have bought from us since 2003. They cover NM cable, 1/2 in. EMT, 1/2 and 3/4 in. PEX and copper, and most bolt work up to 7/8 in. Online, the long Power Pole bits lead: three of every four Power Pole bits ordered on our site this year were 36 in.

A starting kit for a wiring crew, in 8 in. Standard bits for a right-angle drill:

• 302SL4864, 3/4 in. x 8 in., $27.61 (two-bit minimum)

• 302SL5664, 7/8 in. x 8 in., $30.93 (two-bit minimum)

• 302SL6464, 1 in. x 8 in., $37.24

With the minimums that is five bits for $154.32, a spare in the two sizes that wear out first.

What goes in the bag next to a ship auger?

A ship auger covers deep holes from 3/8 to 1-1/2 in. These cover the jobs it can't:

Not sure which family fits? Types of drill bits sorts every bit we sell by the material it cuts.

Need help choosing a ship auger bit? Call our team at (833) 4-ETOOLS or email sales@eldoradotools.com with the wood you're boring and the bolt or pipe size.

Sources: ITM ship auger and Power Pole spec sheets; IRC 2021 R602.6 (drilling and notching studs); NEC 2023 300.4(A)(1); ASTM B88 and ASTM F876 tube sizes; ANSI C80.3 EMT dimensions.

First published [date], with prices checked in our catalog on Oct 29, 2026.