Repair & maintenance guides

Boat Fuel Additives Explained: What Stabilizers, Ethanol Treatments and Boosters Really Do

The marine store shelf is full of bottles that promise to fix fuel problems. Learn what stabilizers, ethanol treatments, water removers, octane and cetane boosters, cleaners and diesel biocides actually do, what no additive can do, how to dose them by the label and why you should not stack several products in one tank.

Boating on High-Altitude Lakes: Power Loss, Prop Changes, Cold Water and Mountain Weather

Engines lose roughly 3% of their power for every 1,000 feet of elevation, so a boat that flew at sea level can struggle on a mountain lake. Learn what's normal, when a lower-pitch prop or a dealer adjustment helps, and how to handle the strong sun, cold water and fast-changing weather up high.

Damaged Propeller: Repair It or Replace It?

Decide whether a bent, chipped or spun prop is worth sending to a prop shop or should be replaced, what a shop can actually fix on aluminum and stainless props, and how to keep the boat running the same afterward.

Electric Outboard Care: Battery Storage, Connectors, Saltwater Rinse and Updates

Electric outboards like Torqeedo, Mercury Avator and ePropulsion need far less work than gas engines, but the lithium battery, the connectors and the prop still need care. Charge and store the battery the way the maker says, keep plugs dry and clean, rinse after salt water, check the prop, fin and anodes, install updates, and follow the rules for transporting lithium batteries.

Engine and Gearbox Oil Analysis: How to Take a Clean Sample and Read the Report

A lab oil analysis is like a blood test for your engine, transmission or lower unit. Learn how to pull a clean sample, what the lab measures, what wear metals, coolant, sea water and fuel in the oil can mean, and why the trend over several samples matters more than any one number.

Ethanol (E10) Fuel Care: Stabilizer, Phase Separation, Fuel Lines and Tank Vents

Keep E10 gasoline from damaging your boat engine. Learn how to use stabilizer, test for water and phase separation, and inspect the fuel lines, primer bulb, anti-siphon valve and tank vent. Most fuel-related breakdowns start with one of these.

Generator Pre-Trip Check: What to Inspect and Test Before a Cruise

A marine generator that quits on the first hot night of a cruise usually gave warning signs at the dock. Use this pre-departure checklist, based on generator makers' own advice, to inspect the oil, coolant, belt, raw-water side, exhaust and CO alarms, run the set under real load, and pack the right spares.

Gyro Stabilizer Care: Owner Checks for Seakeeper and Other Boat Gyros

A gyro stabilizer needs little from you, but what it needs matters. Learn how to start and shut it down correctly, keep its seawater cooling and zinc in shape, rinse it, read its hours and alarms, winterize it, and know which jobs belong to a certified dealer.

How to Add and Read an Outboard Water Pressure Gauge

A water pressure gauge shows how hard your outboard's water pump is working, so you can spot a tired impeller or a clogged intake long before the overheat alarm sounds. Learn why it's worth having, how readings change with RPM and brand, how a gauge is plumbed in, and what to do when the number drops.

How to Break In a New or Rebuilt Boat Engine

The first hours on a new or rebuilt engine decide how well its piston rings seat and how long it lasts. Learn how to follow your maker's hour and RPM schedule, why you should keep changing the throttle, what to avoid (constant RPM, early full throttle, long idling), what to check every trip and when to do the first oil change.

How to Change Lower Unit (Gearcase) and Sterndrive Oil

Drain and refill the gear oil in your outboard lower unit or sterndrive, and learn to spot water intrusion before it destroys the gears. It is a 30-minute job that protects a gearcase costing thousands to replace.

How to Change the Oil and Filter on a 4-Stroke Outboard

Drain the old oil, swap the filter and refill with the right marine oil on your 4-stroke outboard. It is the most common service job, takes about an hour, and costs a fraction of the dealer price.

How to Diagnose and Replace an Outboard Primer Bulb

A primer bulb that won't firm up, collapses while you run, stays rock hard or weeps fuel is telling you something. Learn what each symptom means, how to rule out the tank vent and connectors first, then fit a low-permeation bulb with the arrow toward the engine, clamp it right and test it.

How to Find Your Engine's Serial Number, Model and Year (and Get the Official Manual)

Find the ID label on your outboard, sterndrive, inboard diesel or PWC, read the model and serial number correctly, tell it apart from the boat's HIN, and use it to open the free official owner's manual. It's the first step for ordering the right parts and following the right maintenance plan.

How to Flush an Engine While the Boat Stays in the Water

Boats kept in a saltwater slip, on a mooring or on a lift can't always use flush muffs. Learn how built-in outboard flush ports, sterndrive and inboard flush kits and flush-valve seacocks work, which engines can use them in the water, how to avoid back-flow and hydrolock, and a simple after-every-trip routine.

How to Flush Your Engine With Fresh Water

Rinse salt, silt and sand out of your outboard or sterndrive cooling system using the built-in flush port, flush muffs or a flush bag. Flushing after every saltwater trip is one of the easiest ways to prevent corrosion and overheating.

How to Get Better Fuel Economy From Your Boat

Boat fuel is expensive, but most owners can stretch every gallon further without buying anything. Learn how to find your boat's most efficient cruise RPM, why a clean bottom, the right prop, good trim and less weight matter most, which tune-up items count, how fuel flow data helps, and which fuel-saving myths to ignore.

How to Grease Your Outboard's Lubrication Points

Grease the swivel bracket, tilt tube, steering and shift linkages, trim rams and prop shaft splines on your outboard. Grease keeps salt and water out of the moving joints. A 30-minute job once or twice a season prevents seized steering, stuck props and corroded brackets.

How to Inspect and Replace Sacrificial Anodes (Zincs)

Check the anodes on your outboard, sterndrive or inboard running gear, replace them when they are half gone, and choose the right metal for the water you boat in. Fresh anodes are cheap insurance against expensive corrosion damage to your lower unit, drive and prop.

How to Inspect and Replace Spark Plugs

Pull, read and replace the spark plugs on a gas outboard, sterndrive, inboard or PWC. Fresh, correctly gapped plugs help the engine start easily and run smoothly, and the old plugs tell you a lot about the engine's health.

How to Keep a Boat Maintenance Log and Organize Your Receipts

Set up a simple maintenance log that records the date, engine hours, work done, parts and who did it, and keep receipts and photos organized. Good records help with warranty and insurance claims, show buyers the boat was cared for and reveal wear patterns before something fails.

How to Maintain Your Mainsail Reefing System and Practice a Reef at the Dock

Check the reef lines, blocks, hooks and cringles of a slab (jiffy) reefing system, keep in-mast and in-boom furling mains running smoothly, and practice tucking in a reef at the dock so it is quick and safe when the wind comes up.

How to Remove and Reinstall an Outboard Gearcase (Lower Unit) Without Losing Shift

Dropping the lower unit is the first step of every outboard water pump job, and the reinstall is where most DIY trouble starts: no forward gear, no cooling water or a driveshaft that will not seat. Learn how to set the shift position, protect the water tube, line up the splines and test everything before the boat goes back in the water.

How to Replace a Fuel/Water Separating Filter (and Check for Water in Your Fuel)

Swap the spin-on fuel/water separator on your gas boat and learn to spot water and ethanol phase separation before it stalls the engine. It is one of the cheapest jobs on the boat and one of the best protections for a fuel-injected engine.