Sheared Propeller Pin? How to Replace It On the Water

Your engine's revving high but you're not moving. Chances are you sheared the pin. I've walked hundreds of boat owners through this fix over the past 20 years, and most of the time you can handle it right there on the water without a tow back to the ramp.

What You're Dealing With: Shear Pin vs Drive Pin

Before you start pulling things apart, know which pin you actually have. Outboards use shear pins—they're designed to break when you hit something hard. Trolling motors use drive pins, which are just keepers that hold the prop on the shaft. They look similar, but their jobs are completely different.

Shear Pins on Outboards

The shear pin is your motor's cheapest insurance policy. When your prop strikes a submerged rock or log, the pin snaps before the force can travel up into your lower unit gears. As Yamaha's Dan Power puts it, "the idea of that shear pin is that when you do hit something the shear pin actually breaks it's compromises other than vital internal uh components of the motor." Side-Power's technical docs say the pin "is designed to break in most instances of sudden impact of the props against debris… to help minimize potential damage to the gearleg and motor."

I've seen lower unit repairs run $800–$2,000. A shear pin costs about two bucks. You do the math.

Drive Pins on Trolling Motors

Drive pins don't break on purpose—they're solid retaining pins that lock the propeller to the shaft. If one fails, it's usually because it corroded, bent, or wasn't sized right to begin with. Newport Vessels specs their pins at 1" length x 1/8" diameter for 55lb–86lb thrust motors, and 1" x 1/16" diameter for 36lb–46lb motors. Those dimensions matter. A loose fit means the pin will work its way out; too tight and you'll never get it in.

How to Tell Which One Failed

Sheared pin symptoms: Engine revs instantly to high RPM with zero forward movement. You'll hear it scream. Usually happens right after you felt a hard thunk through the tiller or wheel.

Spun drive pin symptoms: Prop feels loose or rattles on the shaft. Sometimes you'll get intermittent drive—works for a second, then freewheels. Often silent or just a faint clicking.

Spun rubber hub (not a pin problem): Engine sounds normal under load, but prop doesn't turn. The rubber insert inside the prop hub has separated from the outer shell. Swapping the pin won't fix this—you need a new prop.

Tools and Spares to Carry

Keep this stuff in a small drybag zip-tied inside your engine cowling or taped to the trolling motor mount:

• Needle-nose pliers
• 10mm, 12mm, and 13mm sockets or combo wrenches (most outboard prop nuts)
• 2–3 spare shear pins (match your motor's OEM spec, usually 3/16" x 7/8" stainless for small Yamahas and Mercuries)
• 2–3 spare cotter pins
• Small tube of marine wheel bearing grease (Triple-Guard or equivalent waterproof formula)
• 1/8" or 3/16" punch (optional, for stuck pins)

Total cost: under $15. Total aggravation saved: immeasurable.

Step-by-Step: Replacing a Shear Pin on an Outboard

Estimated time: 10–15 minutes if nothing's seized.

Safety First

Shut off the engine. Pull the key. Disconnect the spark plug wire—one stray spark and that prop can spin while your hand's on it. If you're drifting in current or wind, drop an anchor or tie off to a buoy before you start. Tilt the motor up so the prop clears the water; this keeps you from dropping parts overboard and makes the whole job easier.

Remove the Old Hardware

Straighten the cotter pin (split pin) with your pliers and pull it out. Sometimes these corrode into a crusty lump—if it won't budge, cut it with side-cutters. Next, loosen the prop nut. Most small outboards use a 12mm or 13mm. Don't lose the washers. There's usually a thrust washer and a flat washer—keep them in order. Slide the prop straight off the shaft. Watch out for fishing line wrapped around the shaft behind the prop; it can bind things up and make you think the pin's still holding when it's already gone.

Extract the Broken Shear Pin

If you're lucky, the broken pin will fall right out. More often, half of it is still jammed in the shaft hole. Grab it with needle-nose pliers and wiggle it out. If it's completely flush or bent, use a small punch (1/8" works well) and tap it gently from the opposite side—just enough to get it moving. Do not hammer. You can dimple the shaft or crack the prop hub if you get aggressive.

Install the New Pin

Coat the new shear pin in marine grease. This does two things: helps it slide in smoothly now, and prevents galvanic corrosion so you can actually get it out next time. In saltwater, ungreased stainless pins can seize to aluminum shafts in a matter of weeks.

Slide the greased pin through the hole in the driveshaft. It should go in with light finger pressure—if you're forcing it, the diameter is wrong. Line up the slot in the prop hub with the pin and slide the prop back onto the shaft. The prop should seat flush against the thrust hub with the pin centered in the hub recess.

Reassemble and Secure

Put the washers back on in the same order they came off. Thread the prop nut on and snug it down. You want it tight enough that the prop doesn't wiggle side-to-side on the shaft, but you're not torquing it like a lug nut. Overtightening can actually cause the shear pin to bind and not shear when it's supposed to.

Insert a new cotter pin through the castle nut and shaft hole. Bend the long leg over the end of the shaft and the short leg down the side of the nut to lock it. Spin the prop by hand—should turn smoothly with no vertical play or wobble.

Reconnect your spark plug wire, lower the motor, and test at idle before you throttle up.

Troubleshooting Stuck or Repeated Failures

Pins That Won't Come Out

If the old shear pin is corroded or bent and won't tap out, you've got two options. First, try penetrating oil—spray it into the shaft hole from both sides and let it sit for 10 minutes. Then tap again. If it's still locked, you can apply very gentle heat with a small butane torch to the shaft (not the prop). Heat expands the aluminum shaft slightly and can break the corrosion bond. Work in 10-second intervals and keep a wet rag handy. Aluminum melts around 1,200°F; a pocket torch won't get you there, but you can warp the shaft if you sit on one spot too long.

Shear Pins That Keep Shearing

If you're snapping pins every few hours of runtime—and you're not constantly hitting things—something else is wrong. Common causes:

• Wrong pin diameter. Even 1/64" undersize can let the pin rattle and fatigue-fail from vibration. Verify your OEM spec.
• Bent prop shaft. If the shaft has even a slight bend from a previous strike, it puts side-load on the pin. Spin the prop slowly by hand and watch the blade tips—if they trace an oval instead of a circle, your shaft is bent.
• Damaged prop hub. Inspect the recess in the hub where the pin sits. If it's wallowed out or cracked, the pin can't do its job. You'll need a new prop.
• Shifting at high RPM. Slamming from forward to reverse at 3,000 RPM can shock-load the pin. Throttle down to idle before shifting.

I worked with a customer in Queensland, Australia, who was shearing pins every trip on his 6HP Tohatsu. Turned out he'd been using generic hardware-store pins that were slightly undersize. Once we matched his engine serial number and shipped him the correct OEM-spec pins, problem solved. For help with identifying your engine's serial number, feel free to check our guide.

Step-by-Step: Replacing a Drive Pin on a Trolling Motor

Estimated time: 5–10 minutes.

Disconnect Power

Unplug the battery or pull the breaker. Trolling motors don't have spark plugs to disconnect, but you don't want it accidentally energizing while your hand's near the prop.

Remove the Propeller Nut

Most trolling motor props are held on by a single nut with a built-in washer. Size varies—Minn Kota and MotorGuide typically use 10mm. Loosen and remove the nut. The prop should slide straight off. If it's stubborn, tap the back of the hub lightly with a rubber mallet.

Remove the Old Drive Pin

Once the prop's off, you'll see the drive pin running through the shaft. On some motors it'll slide right out; on others it's a press fit and you'll need to tap it from one side with a punch or the shaft of a small screwdriver. Do not reuse the old pin. Even if it looks fine, it may have developed micro-cracks or corrosion that'll cause it to fail.

Install the New Drive Pin

Match the diameter and length exactly. For Newport Vessels 55lb–86lb motors, that's 1" x 1/8". For 36lb–46lb, it's 1" x 1/16". Generic stainless pins from a hardware store will work in a pinch, but they're usually Grade 2 or Grade 5 steel with lower shear strength than marine-spec stainless (often 316 grade). If you're in saltwater or brackish water, the wrong alloy will corrode faster.

Grease the new pin and slide it through the shaft. It should protrude evenly on both sides. Align the prop hub slot with the pin and slide the prop onto the shaft. Reinstall the nut and snug it down. The prop should spin freely by hand with no side-to-side wobble.

Hardware Store Emergency Fixes

You're two hours from the nearest marine dealer and you don't have a spare. Can you limp home on a generic pin from the hardware store? Sometimes.

For shear pins, you're looking for stainless steel rod stock, 3/16" diameter for most small outboards. Buy a 12" length and cut it to size—usually 7/8" to 1". Grease it and install it like the OEM pin. It'll get you back to the dock. The problem is that generic stainless rod is often 304 grade (not 316 marine grade), and the shear strength might not match OEM specs. It could break too easily, or worse, not break at all when you hit something.

For drive pins, you can sometimes find small-diameter stainless dowel pins or roll pins that'll work temporarily. Measure twice. A pin that's even 0.010" undersize will rattle loose. A pin that's oversize won't fit without forcing it, and forcing it can crack the prop hub.

Bottom line: These are get-you-home fixes, not permanent solutions. Order the correct part as soon as you're off the water. To find genuine and OEM parts directly from the factory, explore our large selection of inboard & outboard motor parts at JLM Marine.

Matching Pin Size to Thrust Rating

The thrust rating stamped on your trolling motor's serial plate tells you which size prop and pin you need. This number—36lb, 55lb, 86lb, etc.—represents the motor's maximum forward thrust and correlates directly to shaft diameter and prop hub specs.

Lower-thrust motors (36lb–46lb) use smaller-diameter shafts and correspondingly smaller drive pins, typically 1/16" diameter. Higher-thrust motors (55lb–86lb) step up to 1/8" pins to handle the increased torque. Mixing them up won't work—a 1/16" pin in a 1/8" hole will rattle and fall out; a 1/8" pin won't fit a 1/16" hole at all.

The serial plate or owner's manual will list the exact prop part number for your motor. Cross-reference that to get the pin spec. Or call us at JLM Marine with your motor model and serial number, and we'll pull the exact fit from our database. We stock OEM-spec pins for Minn Kota, MotorGuide, Newport Vessels, and dozens of other brands, shipped direct from the factory to your door—whether you're in Kentucky or Sydney. For assistance with serial numbers, check our Yamaha Outboard Serial Number Guide (2025).

Saltwater vs Freshwater Considerations

If you run in saltwater or brackish estuaries, galvanic corrosion is your enemy. Stainless steel pins and aluminum shafts create a battery when submerged in saltwater. Within a few weeks, the pin can corrode into the shaft so badly that you'll need heat and penetrating oil just to remove it.

Saltwater boaters: Pull and inspect your shear pin or drive pin every 4–6 weeks during the season, even if you haven't hit anything. Pull it, clean the shaft hole with a wire brush, re-grease, and reinstall. This 5-minute maintenance step will save you an hour of fighting a seized pin later.

Freshwater boaters: You can stretch inspections to 2–3 months, but still grease every reinstall. Freshwater slows corrosion but doesn't stop it.

For insights on avoiding corrosion and related engine care, you may also want to reference our blog on Saltwater Use and Overheating: Prevention Tips.

When to Stop and Call a Pro

Most pin replacements are simple enough to do on the water or at the dock. But if you see any of these red flags, stop and get a professional diagnosis:

• Gear oil leaking from the lower unit seals (milky or black oil dripping from the prop shaft)
• Cracks in the lower unit housing, especially around the skeg or prop shaft
• Prop shaft that won't turn by hand even with the prop removed
• Grinding or clunking noises from inside the lower unit when you turn the prop
• Prop shaft with visible bends or kinks (blades trace an oval when spun)

These symptoms mean internal damage—sheared gears, bent shafts, or failed bearings. A new shear pin won't fix them, and running the motor in that condition will only make the repair bill worse. For detailed troubleshooting on propeller and gear issues, see our guide on Propeller Vibrations: Diagnosing Bent Shafts or Blades.

OEM vs Aftermarket Pins

OEM pins from Yamaha, Mercury, or Minn Kota are good parts. No question. But you're paying a 40–60% markup for the logo on the package. A Yamaha-branded shear pin might run $4–$5 at a dealer; the same pin from a reputable aftermarket supplier is $1.50–$2.

Here's what most boaters don't realize: many aftermarket manufacturers produce parts in the same factories that make OEM components. They use the same specs, same materials (316 stainless, Grade 5 steel, etc.), and the same tolerances. The difference is they don't pay licensing fees to the engine brand, so they can sell for less. JLM Marine sources from these factories. You get factory-spec quality without the dealership markup.

Avoid the junk. If you see a "universal fit" shear pin kit for $5 on a marketplace site with no material specs listed, that's a red flag. The pins are often made from mild steel (not stainless), incorrect diameters, or wrong lengths. They'll either break prematurely or won't break when they're supposed to, which defeats the whole purpose.

Quick Visual ID: Is It a Shear Pin or Drive Pin?

If you're not sure which type you're looking at, here's how to tell by sight:

Shear pins often have visible score marks or grooves near the center—these are engineered weak points designed to concentrate stress and ensure a clean break. They're usually stainless and may have slight discoloration (straw or blue tint) from heat-treating. When they break, the fracture surface is typically clean and perpendicular to the length of the pin.

Drive pins are uniform cylinders with no grooves or score marks. They're solid from end to end. Material is often stainless, brass, or zinc-plated steel depending on the motor brand. If they fail, it's usually from bending or shearing at an angle, not a clean break.

Pro Trick: Tape a Spare to Your Cowling

Here's what I do on my own motors, and I tell every customer to do the same: take your spare shear pin, spare cotter pin, and a dab of grease, wrap them in a small ziplock bag, and tape or zip-tie the bag inside your outboard cowling or to the underside of your trolling motor mount. Use marine-grade adhesive zip-tie mounts if you're in rough water.

That way, when you shear a pin five miles offshore or in the middle of a bass tournament, you're not digging through compartments or realizing you left the spares in the garage. It's right there, 30 seconds from your hand.

Final Maintenance Tip

Every time you pull your prop for any reason—line removal, cleaning, or pin replacement—give the prop shaft a good coat of fresh waterproof marine grease before you slide the prop back on. This prevents corrosion, makes future prop removal easier, and protects the shaft splines on motors that use them. Takes 10 extra seconds and extends the life of your hardware by years.

For additional marine parts and accessories to keep your boat in top shape, check out our boat accessories collection and explore the full range of JLM Marine parts.