Propeller School
Understand it before you buy it.
Boat owners are educated buyers — they talk in marinas and they check the physics. Good: here's the physics, in plain language, including the parts that don't sell propellers.
Something's wrong
The symptom checker
Pick the symptom, get the cause tree and the free checks first.
I want to understand
The glossary
40+ terms plainly defined — the reference the whole site links to.
I'm deciding
The honest comparison
Every propeller type's trade-offs, from the company that builds them all.
Propeller basics: diameter, pitch, slip and blades
The four numbers that describe every propeller — and why 'the biggest prop that fits' is a myth that costs you fuel.
Read →7 min readPropeller sizing explained: what we need and why
Power, max RPM, gearbox ratio, shaft and clearance — what each number does in the sizing calculation, and which ones owners most often get wrong.
Read →8 min readFolding vs feathering vs fixed: choosing a low-drag propeller
The complete decision guide — drag, powered performance, reverse, motor-sailing and cost of ownership for each architecture, from a company that builds all three.
Read →5 min readPropeller drag under sail: what you're really towing
A fixed prop drags like a bucket — the numbers behind the cliché, what feathering and folding actually save, and why light air is where it matters.
Read →6 min readFuel-efficient motoring: the propeller is the biggest lever
Why the same boat at the same speed can burn 20% less diesel — engine loading, pitch matching and the arithmetic at 2026 Australian fuel prices.
Read →5 min readMotor-sailing: the most under-rated gear your boat has
Sails up, engine ticking over, five hundred miles of light air ahead — why motor-sailing rewards a self-pitching propeller more than any other mode.
Read →6 min readReverse thrust and prop walk: stopping like you mean it
Why reverse is every propeller's weakest gear, what prop walk actually is, and which architectures back down properly.
Read →5 min readSaildrive vs shaft drive: what changes for the propeller
Spline fittings, anodes, clearances and water flow — the practical differences between the two drivetrains when it's time to choose a propeller.
Read →6 min readCatamaran propellers: twin drivetrains, doubled stakes
Handed pairs, saildrive splines, one-engine passage-making and why multihulls show the biggest documented gains from a propeller upgrade.
Read →6 min readElectric boat propellers: range is a propeller problem
Why electric conversions under-deliver, what regeneration really requires, and how propeller efficiency converts directly into usable range.
Read →5 min readPropeller maintenance: anodes, grease, fouling and bearings
The unglamorous fifteen minutes a year that keeps a precision propeller performing like one.
Read →6 min readVibration and noise: reading what the boat is telling you
RPM-dependent rumble, shaft alignment, fouled blades or the wrong propeller — how to tell which vibration you have and what actually fixes it.
Read →5 min readWhen an Autoprop is the wrong choice
The honest page no competitor publishes: the five situations where we'll talk you out of our own flagship propeller — and what we'll recommend instead.
Read →5 min readQuestions to ask any propeller supplier (including us)
The buyer's checklist: six questions that separate engineering-led propeller suppliers from box-shifters — with the answers you should expect.
Read →4 min readHow to read propeller marketing
A friendly decoder of the industry's claim patterns — 'up to' arithmetic, baseline-free percentages, magic-rpm efficiency figures — and the MEASURED/MODELLED standard this site holds itself to.
Read →6 min readFouling in Australian waters: a regional guide for propeller owners
Tropical Queensland grows barnacles like a business; Tasmania barely tries. What Australia's fouling gradient means for low-drag propellers, cleaning intervals and coatings.
Read →6 min readMarina electrics and stray current: the corrosion nobody budgets for
A Victorian boat lost a $40,000 bow thruster to stray current. How marina berths become corrosion hot zones, what shore power has to do with it, and how monitoring beats guessing.
Read →7 min readThe sizing walkthrough: finding every number the Builder asks for
Where the engine plate lives, where the gearbox plate hides by brand (ZF, PRM, Hurth, Kanzaki, Twin Disc), how to measure shaft diameter, and how to eyeball tip clearance — with the camera as your notebook.
Read →Learned enough to be dangerous?
Good. The Builder turns the theory into a recommendation for your actual boat — and an engineer checks it.