The running gear on a boat is the mechanical chain that turns engine power into forward motion, and it lives in the harshest spot on the vessel: fully submerged, spinning at speed, and soaking in salt water that wants to eat metal and grow barnacles on everything. When people say running gear, they mean the whole underwater drivetrain aft of the transmission: the propeller shaft, the shaft coupling, the shaft seal, the strut and its cutlass bearing, the propeller itself, and, on most boats, the rudder and its bearings. Get any one of those parts wrong and you feel it everywhere. A shaft that is out of shaft alignment by a few thousandths of an inch will chew through a seal, hammer a coupling, and vibrate a hull until the fillings rattle out of your teeth. That is why propeller shaft repair and running gear service is one of the most common, and most misunderstood, jobs a boat owner pays for.
This guide walks through every piece of the system, how to read the symptoms when something goes bad, the actual process a shop uses to align a shaft and swap a cutlass bearing, the difference between packing glands and dripless seals, how propellers get tuned, and what all of it costs in 2026 dollars at real yards in Florida and the Mediterranean. Whether you turn the wrenches yourself or hand the boat to a machinist, knowing what good work looks like is the difference between paying once and paying three times.
Yacht Service Network is a free marketplace that connects boat owners with vetted shaft shops, machinists, and haul-out yards. Post what your boat needs and get responses from local pros who actually do this work every day.
Create your free accountBefore you can troubleshoot anything, you need a clear picture of the parts and how they connect. Power leaves the transmission at the output flange. From there it flows through the coupling, down the shaft, into the propeller, and out into the water. Everything that holds that shaft steady, keeps water out of the boat, and stops the metal from corroding is part of the running gear package.
The propeller shaft is a solid round bar, usually a marine bronze alloy like Aquamet 22 or Aquamet 19, sometimes stainless in the 316 or 17-4 family on higher-end builds. Diameters on recreational and light commercial boats run from about 1 inch on a small sailboat auxiliary up to 2.5 inches or larger on a big sportfish or motoryacht. The shaft has a taper and keyway machined at the aft end where the propeller mounts, and a flange or a bolted coupling at the forward end where it joins the transmission. A shaft is not a throwaway part. A good bronze shaft can outlast several sets of bearings and seals, but it will bend if you strike a log or run aground under power, and once it is bent even a little it destroys everything downstream.
The coupling is the bolted joint between the transmission output flange and the shaft. On many boats it is a simple rigid flange coupling, either a solid one-piece unit pressed and pinned onto the shaft or a split clamp-style coupling you can service without pulling the shaft. Higher-end drivetrains use a flexible coupling like a ZF or Centa unit, which absorbs a small amount of engine movement and misalignment and takes some torsional shock out of the driveline. The coupling face is a reference surface for alignment: when a mechanic checks alignment, they are measuring the gap between the transmission flange and the coupling flange all the way around.
Where the shaft passes through the hull, something has to stop the ocean from coming in while still letting the shaft spin. That is the shaft seal, and it comes in two families. The traditional option is a stuffing box, also called a packing gland, which uses rings of flax or synthetic packing squeezed around the shaft. The modern option is a dripless seal like a PSS from PYI or a Tides Marine lip seal. We cover the two types in detail later because choosing between them is one of the more consequential decisions an owner makes.
On boats where the shaft exits the hull and runs some distance to the propeller, a strut supports the shaft near the prop so it does not whip around. Inside the strut sits the cutlass bearing, a cylindrical sleeve with a brass or composite shell and a grooved rubber lining. Water flows through those grooves and lubricates the bearing while the shaft rides on the rubber. Duramax Marine and Johnson Cutless are the two names you see most. The cutlass bearing is a wear part. It is designed to fail before the shaft or strut does, and replacing it on schedule is cheap insurance against a much bigger repair.
The propeller converts shaft torque into thrust. Recreational props are usually manganese bronze or the stronger nibral (nickel bronze aluminum) alloy, three, four, or five blades depending on the boat and the mission. A prop that is dinged, bent, or out of pitch wastes fuel, adds vibration, and loads the whole drivetrain unevenly. Propeller tuning and repair is a specialty trade with its own shops and its own tooling.
The rudder is not part of the propulsion path, but it lives in the same underwater neighborhood and shares the same enemies: corrosion, marine growth, and worn bearings. When you have the boat hauled for running gear work, the rudder, its stock, and its upper and lower bearings get inspected at the same time because the labor to reach them is already spent.
Running gear rarely fails without warning. The trouble is that most owners feel the early symptoms and either ignore them or blame the wrong part. Vibration gets blamed on the engine, a growling noise gets blamed on the transmission, and a slow leak gets mopped up and forgotten until the bilge pump runs constantly. Learning to connect the symptom to the actual cause saves money and prevents the kind of failure that leaves you drifting.
The most common complaint is vibration. A little vibration at certain RPM can be normal, but new vibration, or vibration that gets worse over a season, always means something. The classic sources are a bent shaft, a damaged propeller, a worn cutlass bearing, or a shaft that has drifted out of alignment. Each one has a slightly different signature. A bent shaft or an out-of-balance prop usually vibrates in proportion to RPM: faster shaft, more shake. A worn cutlass bearing tends to produce a rhythmic knock or a rumble that comes and goes as the shaft moves in the loose rubber. Misalignment often shows up as vibration that is worse in gear than in neutral, plus premature seal and coupling wear.
Noise is the second big signal. A growl or a squeal from the stern area, especially at low speed or when you first engage the transmission, points at a dry or worn cutlass bearing. A knock or a clunk when you shift from forward to reverse can be a worn coupling, a loose set screw, or excessive play in the bearing. Water noise, a whooshing or gurgling around the stuffing box, means the seal is not sealing.
Leaks are the third. A traditional packing gland is supposed to drip a small amount when the shaft turns, roughly two to three drops a minute, and be nearly dry at rest. A steady stream, or dripping when the boat is sitting still, means the packing is worn out or the gland needs adjusting. A dripless seal that leaks at all is a problem, because it is designed to stay bone dry.
| Symptom you notice | Most likely cause | What to check first |
|---|---|---|
| Vibration that increases with RPM, same in gear and neutral once spinning | Bent shaft or out-of-balance / damaged propeller | Dial-indicate the shaft for runout; inspect prop blades for dings and bends |
| Vibration worse in gear than neutral, seal and coupling wearing fast | Shaft alignment out of spec | Check flange gap with feeler gauges at four points |
| Rumble, knock, or rhythmic thump from the stern, worse at low speed | Worn cutlass bearing | Grab the shaft near the strut and feel for play; inspect rubber lining |
| Growl or squeal on engagement or at idle | Dry or glazed cutlass bearing, blocked water flow | Confirm water is reaching the bearing; look for wear grooves |
| Clunk when shifting forward to reverse | Loose coupling, worn coupling, or set-screw play | Check coupling bolts and set screws; inspect flexible coupling element |
| Steady drip or stream at the stuffing box, even at rest | Worn packing or gland out of adjustment | Adjust gland nut; if no improvement, repack |
| Any water at a dripless seal | Failed bellows, worn seal faces, or lost spring tension | Inspect bellows and carbon/stainless faces; check for hardening |
| Pink or white powdery deposits on bronze, rapid anode loss | Galvanic corrosion / stray current, dezincification | Test anodes, check bonding, look for stray-current sources at the dock |
| Rope or line wrapped and burning smell | Fouled prop overheating shaft seal | Haul or dive to clear; inspect seal for heat damage |
List your machine shop or running gear business on Yacht Service Network for free and get found by owners and captains searching for exactly the work you do. No lead fees, no commissions.
Create your free accountShaft alignment is the single most important running gear service, and it is the one most often skipped. The idea is simple: the transmission output flange and the shaft coupling flange must meet each other perfectly square and perfectly centered, so the shaft runs true through its bearings and seal without side load. When they do not meet square, the shaft is forced to bend a tiny amount every single revolution. At 2000 RPM that is more than 33 flex cycles a second, and it destroys seals, wears bearings, hammers couplings, and telegraphs vibration into the hull.
Alignment drifts over time for reasons that have nothing to do with the shaft itself. Engine mounts sag and compress with age and heat. A wooden or fiberglass hull flexes and settles. A grounding or a hard hit shoves the strut. Even hauling the boat and setting it on the hard changes the hull shape enough that a boat aligned in the water and then aligned again on stands will read differently. That is why serious yards do a final alignment with the boat back in the water and the hull loaded normally, after the rig and fuel and gear are aboard.
The classic method uses feeler gauges at the coupling. The mechanic separates the coupling halves slightly, brings them back together, and measures the gap between the two flange faces at the top, bottom, and both sides. The goal on most installations is that the gap is even all the way around, within about 0.001 inch per inch of coupling diameter. A 4 inch coupling should be within roughly 0.004 inch total. If the gap is wider at the top than the bottom, the engine tail needs to come up or go down; if it is wider on one side, the engine shifts sideways. The mechanic adjusts the engine mounts, not the shaft, moving the transmission end until the flanges kiss evenly.
Good shops also check shaft runout with a dial indicator to make sure the shaft itself is straight before they trust any coupling reading. A bent shaft will give a false alignment number because the flange wobbles as it turns. They rotate the shaft and watch the indicator; more than about 0.002 to 0.003 inch of runout means the shaft or coupling needs attention before alignment can be trusted. On boats with a flexible coupling, alignment still matters, because the flexible element is meant to absorb small movement, not compensate for a badly set engine.
Expect a straightforward alignment on a single-engine boat to take an hour or two of labor. On a twin-engine boat, or one where the mounts are seized or corroded and have to be freed up first, it takes longer. Alignment is cheap relative to what it protects, and it is the first thing a competent shop checks when an owner reports vibration or a seal that keeps failing.
The cutlass bearing is the most common running gear replacement, and for good reason: it is designed to wear out. The rubber lining rides against the spinning shaft with water as the only lubricant. Sand, grit, and running dry (from a fouled water passage or from sitting on a mud bottom) all accelerate wear. Over time the rubber grooves round off, the bearing develops slop, and the shaft starts to rattle inside it. Left long enough, a badly worn cutlass bearing lets the shaft move enough to throw off alignment, damage the seal, and in the worst case wallow out the strut itself.
You test for wear by hand. With the boat hauled, grab the shaft right at the strut and try to move it up, down, and side to side. A little movement is normal, but if you can feel a distinct clunk or see daylight change at the bearing, it is time. Most shops also just replace the bearing on a schedule, every three to five years or so depending on hours and conditions, because the part is inexpensive and the labor to reach it is already being spent during a haul-out.
There are two ways a bearing sits in a strut: pressed in with a friction fit, or held by set screws that lock it in place. Either way the shaft has to come out or slide back far enough to clear the strut. That means uncoupling the shaft at the transmission, pulling the propeller, and sliding the shaft aft. With the shaft clear, the old bearing gets pressed, pushed, or cut out. Some shops use a purpose-made bearing puller; others make a cut lengthwise with a careful hacksaw or a special tool and collapse the shell inward so it slides out without scoring the strut bore. The strut bore then gets cleaned, the new Duramax or Johnson cutlass bearing gets lubricated and pressed in with the water grooves oriented correctly, the set screws (if fitted) get seated, and the shaft goes back in. Then the whole thing gets realigned, because pulling and reinstalling the shaft changes the geometry.
The wrong way to do this job is to force the bearing with heat and a hammer, score the strut bore, or install the bearing dry. A scored bore never holds the next bearing properly, and a dry-installed bearing can spin in the strut. This is exactly the kind of job where a specialist earns the money: they have the puller, they have the press, and they have done it a hundred times.
Captains and fleet managers use Yacht Service Network to line up haul-out yards, shaft shops, and drivetrain service across multiple boats in one place. Track who did what, when, and get quotes from vetted pros in Florida, the Med, and beyond.
Create your free accountThe shaft seal is where the ocean meets the inside of your boat, so it deserves careful thought. There are two philosophies, and boat owners argue about them the way they argue about anchors. Both work. Both have failure modes. Knowing how each behaves helps you pick the right one and service it correctly.
A stuffing box is a bronze fitting with a nut that compresses rings of packing material around the shaft. Traditional packing is flax impregnated with wax and grease; modern packing uses PTFE-loaded synthetics or graphite-impregnated fibers like GFO that run cooler and last longer. The design is meant to drip. The controlled drip, two to three drops a minute while the shaft turns, cools the packing and flushes out grit. If you crank the nut down until it stops dripping entirely, you cook the packing and score the shaft.
The strength of a stuffing box is simplicity and serviceability. There is nothing to fail catastrophically. You can repack it in the water on many boats by backing off the nut, digging out the old rings, and winding in new packing, and the parts cost is trivial. The downside is that little steady drip, which keeps the bilge damp and eventually can score the shaft where the packing rides. It also needs periodic adjustment as the packing beds in and wears.
A dripless seal keeps the bilge dry, which is why so many newer boats have them. There are two main mechanical types. The PSS shaft seal from PYI uses a spring-loaded carbon rotor that presses against a polished stainless collar clamped to the shaft. A rubber bellows holds the carbon face and keeps water out while allowing the face to float with shaft movement. The Tides Marine SureSeal is a lip-seal design: a self-aligning housing holds replaceable lip seals that ride directly on the shaft, with a small water feed to lubricate them.
Dripless seals run dry and clean, and a well-installed one is nearly maintenance free for years. But they are not immortal. The PSS bellows is rubber, and rubber ages; PYI recommends replacing the bellows on a schedule, generally around every six years, because a bellows that hardens and cracks can flood the boat. The carbon and stainless faces wear and need burping of trapped air after every haul-out. Tides lip seals wear and get replaced periodically, and the good news there is you can often carry a spare seal on the shaft and swap it without pulling the shaft. Whichever you run, a dripless seal is not a fit-and-forget part. It is a fit-and-remember-the-service-interval part.
If you value dead-simple serviceability, tolerate a damp bilge, and like being able to fix the seal yourself in the water, a packing gland with modern GFO packing is hard to beat. If you want a dry bilge, run in clean water, and will actually keep up with bellows and face replacement, a PSS or Tides dripless is excellent. The failure that hurts people is a dripless seal that never gets serviced because it never leaked, right up until the aged bellows lets go. Put the service interval on the calendar the day it is installed.
A propeller looks like a chunk of bronze, but it is a precision airfoil, and it does not take much to knock it out of true. Hitting a sandbar, sucking up a crab pot line, or just years of cavitation erosion will bend blade tips, round off edges, and shift the pitch. A prop that is out of pitch or out of balance costs you speed, burns extra fuel, and dumps vibration into the whole running gear. Propeller tuning is a real trade with dedicated shops and, at the high end, computer-controlled measurement.
A good prop shop mounts the propeller on a calibrated fixture and measures pitch, blade tracking, and balance against the manufacturer's spec. Shops like Michigan Wheel, Prop Scan certified shops, and regional specialists use gauges or optical scanning to find exactly where each blade is off. They then cold-work the blades back to spec, restore the edges, and rebalance. A properly tuned prop can pick up a fraction of a knot, smooth out vibration, and drop fuel burn, especially if it was noticeably damaged.
There is a difference between a straighten-and-balance and a full class-standard tuning. A basic reconditioning fixes obvious damage and gets you running smoothly again. A precision tuning to a tight tolerance, the kind you would do on a performance sportfish chasing top speed, costs more and delivers a prop that is within a very tight window on every blade. For most owners, a reconditioning every few years, or after any hard strike, is the right call. If you run twins, do both props together so they match, and mark them so left and right go back on the correct sides.
Underwater metal in salt water is a battery whether you want it to be or not. Different metals sitting in an electrolyte (seawater) set up a galvanic cell, and the more active metal gives up its atoms to protect the more noble one. Your bronze shaft, nibral prop, and bronze strut are relatively noble; without protection, the more active metals in the system corrode, and in the worst cases the bronze itself dezincifies, turning pink and crumbly as the zinc leaches out of the alloy.
The defense is sacrificial anodes, commonly called zincs even though many are now aluminum or magnesium. An anode is a lump of a more active metal bolted into the bonding system and clamped to the shaft. It corrodes first, sacrificing itself so the expensive parts survive. A shaft anode (a collar clamped around the shaft), a prop nut anode, hull anodes, and rudder anodes all work together. In salt water, aluminum anodes have largely replaced zinc because they last longer and stay active; in brackish or fresh water, magnesium is the right choice because zinc goes passive and stops protecting.
Anodes are consumables. Inspect them at every haul-out and replace any that are more than about half gone. Anodes that vanish unusually fast are a warning sign. Rapid anode loss often means stray current, frequently from a neighboring boat at the dock leaking DC into the water, or from a wiring fault on your own boat. Stray-current corrosion is much more aggressive than plain galvanic action and can destroy a prop or shaft in a single season. If your anodes are disappearing in weeks instead of months, get the bonding system and the shore-power ground checked, and consider a galvanic isolator or an isolation transformer.
Engineers use Yacht Service Network to find shaft shops, anodes, seals, and machinists in whatever port the boat lands in next. Build your network of trusted suppliers and keep the drivetrain running between yard periods.
Create your free accountMost serious running gear work happens during a haul-out, because you cannot properly inspect or service a submerged drivetrain with the boat in the water. When the travel lift picks the boat and the yard pressure-washes the bottom, the running gear tells its story. A thorough inspection covers the whole system while access is easy and labor is already committed.
The crew checks the propeller for dings, bent tips, and pitting, and spins it to feel for shaft runout and cutlass bearing play. They inspect the shaft for score marks at the seal and for straightness, examine the strut and its mounting for cracks or movement, and look hard at every anode. The seal gets checked: packing condition on a stuffing box, bellows and face condition on a dripless. The rudder gets wiggled to test its bearings, and the bonding wires get inspected for corrosion and continuity. A good yard photographs what they find and gives you a written condition report, not just a verbal "looks fine."
This is the moment to make decisions. If the cutlass bearing has any play and you are already hauled, replace it now rather than paying to haul again in six months. If the bellows on a dripless seal is more than a few years old, do it now. If the prop shows damage, send it to the tuning shop while the boat is on the hard. Batching this work during one haul-out is far cheaper than a series of separate trips, because the haul, block, and launch fees get paid once instead of three times.
| Component | Inspect | Typical replace / service interval |
|---|---|---|
| Sacrificial anodes (shaft, prop, hull, rudder) | Every haul-out | Replace when 40 to 50 percent consumed, often yearly in warm salt water |
| Shaft alignment | Yearly and after any grounding | Adjust as needed; always recheck after shaft or engine-mount work |
| Cutlass bearing | Every haul-out (feel for play) | Replace roughly every 3 to 5 years or when play is felt |
| Stuffing box packing | Each season | Adjust as it beds in; repack every 2 to 4 years |
| PSS / PYI dripless bellows | Every haul-out | Replace bellows about every 6 years; burp faces after each launch |
| Tides Marine lip seal | Every haul-out | Replace lip seal per hours/condition; spare often pre-loaded on shaft |
| Propeller | Every haul-out | Recondition every few years or after any strike; tune twins as a pair |
| Rudder bearings | Every haul-out | Replace when play develops; varies widely by design |
Prices vary with region, boat size, shaft diameter, and how much the shop has to disassemble to reach the parts. The Florida market, with heavy competition among yards from Fort Lauderdale to Stuart to the Gulf coast, tends to run a bit cheaper on labor than the Mediterranean, where yards in places like Palma, Antibes, and Genoa charge premium rates, especially in season. The numbers below are 2026 ballparks in US dollars for a typical single-engine recreational or light sportfish boat. A big twin-engine motoryacht multiplies most of these.
Shaft alignment. A standalone alignment on a single-engine boat usually runs about 150 to 400 dollars in labor at a Florida yard, more if seized mounts have to be freed. Twins roughly double it. When alignment is bundled into a bearing or seal job, it is often included in the quoted labor.
Cutlass bearing replacement. The bearing itself is cheap, often 40 to 150 dollars for a Duramax or Johnson unit depending on size. The labor is where the money goes, because the shaft has to come out. Figure roughly 400 to 900 dollars all in for a single shaft at a typical yard, more if the bearing is seized in the strut or the prop is stubborn. Twins land in the 800 to 1,800 dollar range. Med yards can run noticeably higher.
Shaft seal. A packing gland repack is one of the cheapest jobs on the boat: packing material is a few dollars, and the labor is an hour or two, so budget 100 to 300 dollars if a yard does it. A new PSS dripless seal kit runs roughly 300 to 700 dollars in parts depending on shaft and hull sizes, plus installation. A PSS bellows replacement is the recurring cost, and doing it during a haul is a few hundred dollars in labor plus the bellows kit. A Tides Marine seal kit is in a similar parts range, with the advantage of easy lip-seal swaps.
Propeller tuning. A straighten-and-balance reconditioning at a prop shop typically runs about 150 to 400 dollars per propeller for common recreational sizes. A precision tuning to a tight class standard at a shop like Michigan Wheel or a Prop Scan certified shop costs more, often 300 to 700 dollars or beyond for larger or performance props. Larger sportfish and yacht props scale up quickly with diameter and blade count.
New propeller shaft. If the shaft is bent or badly scored, a new bronze shaft with the coupling machined and fitted runs roughly 700 to 2,500 dollars depending on diameter and length, plus installation and alignment. Stainless shafts cost more.
Haul-out. The haul and launch itself, before any repair labor, commonly runs on the order of 15 to 30 dollars per foot at Florida yards for a short haul, plus daily lay-day charges while the boat is on the hard. So a 40 foot boat might see 600 to 1,200 dollars just for haul, block, pressure wash, and launch before a single part is touched. Med yards, especially the busy superyacht yards, charge considerably more.
The pattern to notice is that the parts are cheap and the access is expensive. That is the whole argument for doing running gear maintenance on schedule and batching it into one haul-out: you pay the expensive haul-and-access cost once and knock out the anodes, the bearing, the seal, and the prop all together. For more on how running gear fits into overall boat maintenance budgeting, see our complete guide to yacht maintenance services and costs, and for the mechanics of the lift itself read our yacht haul-out guide and cost breakdown.
Stop guessing which yard to call. Post your running gear job on Yacht Service Network and get quotes from local machinists, prop shops, and haul-out yards who specialize in shaft, bearing, and seal work.
Create your free accountRunning gear work rewards specialists. General mechanics can handle plenty on a boat, but a shaft alignment done by feel, a cutlass bearing pressed without scoring the strut, and a prop tuned to spec all take dedicated skill and tooling. The best outcomes come from shops that do this work day in and day out: a machine shop with a lathe for coupling and shaft work, a prop shop with balancing gear, and a yard that aligns in the water after launch. When you interview a shop, ask how they check alignment, whether they measure shaft runout, and how they remove a seized cutlass bearing. The answers tell you fast whether they know the trade.
If you are a machinist, prop specialist, or diesel mechanic who does this work, being easy to find matters as much as being good. Owners searching for a shaft shop often do not know who is nearby or who to trust. For a broader look at how marine mechanics build a client base and where the demand is, our marine mechanic guide to services and careers covers the trade from the business side. Getting listed where owners actually search closes the gap between a shop that can do the work and an owner who needs it done.
List your running gear services on Yacht Service Network for free. Owners and captains search by location and specialty, so the boats that need shaft alignment, bearing work, and prop tuning find you directly.
Create your free accountThe clearest test is with the boat hauled: mount a dial indicator against the shaft near the coupling and rotate it slowly. More than about 0.002 to 0.003 inch of runout means the shaft is bent or the coupling is not seated true. In the water, a bent shaft usually shows as vibration that grows with RPM and is present in both forward and reverse. A shaft can be straightened by a machine shop if the bend is mild, but a badly bent shaft is usually replaced, because straightening a hardened marine shaft perfectly is difficult and a marginal one will keep causing trouble.
There is no fixed hour figure, because wear depends on water quality, running hours, and how often the bearing runs dry. As a rule of thumb, plan on roughly every three to five years, and check for play at every haul-out by feeling for movement at the strut. If you run in gritty or shallow water, or if the boat has been aground, inspect more often. Because the labor to reach the bearing is the expensive part, most owners replace it whenever they detect the first real play rather than waiting for it to get bad.
Neither is strictly better; they trade different risks. A dripless seal like a PSS or Tides Marine keeps the bilge dry and needs little routine fiddling, but it has a rubber bellows or lip seal that must be replaced on schedule, and a neglected dripless seal can fail suddenly. A traditional packing gland drips a little and needs periodic adjustment and repacking, but it is dead simple, cheap, and serviceable in the water. If you will keep up with the service interval, a dripless is great. If you would rather have something you can always fix yourself, stick with packing and use a modern low-friction material like GFO.
Normal anode consumption in warm salt water is on the order of one season for a shaft or prop anode. If they vanish in weeks, you likely have stray current, often DC leaking into the water from your own boat or a neighbor's at the dock, or a wiring fault in the bonding system. Rapid, uneven anode loss is a warning that your expensive bronze is at risk. Have the bonding system, shore-power ground, and any nearby boats checked, and consider a galvanic isolator or isolation transformer. Also make sure you are using the right anode metal: aluminum or zinc for salt water, magnesium for fresh or brackish.
Yes, on many single-engine boats, with feeler gauges, patience, and a service manual. The method is to bring the coupling halves together and measure the gap at four points, then adjust the engine mounts until the gap is even within about 0.001 inch per inch of coupling diameter. The catches are that seized or corroded mounts are hard to move, that you should verify the shaft is straight first, and that the final alignment ideally happens with the boat back in the water and loaded normally. If the mounts fight you or the numbers will not come together, a shop with the right tools will save you a frustrating day.
For a typical single-engine recreational boat in 2026, a comprehensive haul-out service covering new anodes, a cutlass bearing, a seal service, an alignment, and a prop reconditioning, plus the haul and launch itself, commonly lands somewhere in the 1,500 to 3,500 dollar range at a Florida yard, depending on boat size and what the inspection turns up. Twin-engine boats and Mediterranean yards run higher. The single biggest way to control the cost is to do the work on schedule and batch it into one haul-out, so you pay the expensive haul-and-access fees once instead of returning every few months for a separate job.
People use the terms loosely and often interchangeably. In common marine usage, running gear refers specifically to the underwater rotating and supporting parts: shaft, coupling, strut, cutlass bearing, propeller, and often the rudder. Drivetrain is a slightly broader idea that also includes the transmission and everything that transmits power from the engine. When a yard quotes running gear service, they mean the underwater parts and the seal, not the engine or gearbox internals.
Whether you need an alignment, a cutlass bearing, a new seal, or a prop tuned, Yacht Service Network connects you with vetted marine specialists for free. Owners, captains, engineers, and shops all in one network.
Create your free accountRunning gear is not complicated, but it is unforgiving. Every part depends on the ones around it. A worn cutlass bearing throws off alignment; bad alignment kills the seal; a fouled prop overheats the shaft; a missing anode dissolves the bronze. Stay ahead of it and the whole system runs quiet and cheap for decades. Fall behind and small problems compound into a bent shaft, a scored strut, and a flooded bilge. The owners who spend the least on running gear over the life of a boat are not the ones who skip maintenance. They are the ones who haul on schedule, check the anodes, feel the bearing for play, keep the alignment true, and fix the small thing before it becomes the big one.
The knowledge in this guide lets you speak the language, read the symptoms, and judge whether the work in front of you was done right. The rest comes down to finding people who do this every day and treating the drivetrain with the respect a fully submerged, high-speed mechanical system deserves. Do that, and the running gear becomes the part of the boat you never have to think about, which is exactly how it should be.