A service manual for the PYI Max-Prop feathering propeller: the Classic, Easy and Whisper designs, the exploded view, and step-by-step assembly and disassembly — built around the gear-timing that makes the Classic tricky. With the official PYI figures. The first of the ESI shaft & drivetrain guides.
Before you start
A service manual for the PYI Max-Prop feathering propeller — the designs, the exploded view, and step-by-step assembly and disassembly, with the official PYI figures. The Classic's gear timing is the part that bites, so most of the care is there; the Easy and Whisper are simpler. Each chapter ends with a check; a final exam unlocks the certificate. This is the first of the ESI shaft & drivetrain service guides.
Record the pitch letter and witness-mark the gear before anything comes apart.
Each prop is matched and balanced — never mix parts.
Grease fwd↔reverse; a good prop feathers in a fraction of a second.
Chapter 1
Know which model is on the boat before you touch it.
A Max-Prop is a feathering propeller. Unlike a folding prop (which opens by centrifugal force), the blades are driven by a differential gear: shaft torque rotates the central cone gear, which turns the blade gears so all blades open to the same angle in forward or reverse, and feather (turn edge-on) when the shaft stops. That gear set is also why assembly is fussy — the gears must be timed correctly.
| Model | Blades | Pitch adjustment | Notes |
|---|---|---|---|
| Classic | 2 & 3 | Internal gear setting (haul-out) | Pre-2019; pitch set by which gear letter lines up with the mark. |
| Easy | 3 & 4 | Swap a bolt (in the water) | Bolt-on; pitch in 2° increments without a haul-out. |
| Whisper | 5 | Swap a bolt | Smoothest/quietest; heavy-displacement boats. |
On the Classic, pitch is built into the gear timing — get it wrong on reassembly and the boat is over- or under-propped, and you're hauling again. On the Easy / Whisper, pitch is just a bolt length you can change at the dock. Most of this guide's care is about the Classic gear timing.
Source: PYI Inc. Max-Prop product pages & instruction manuals (Classic, Easy/Whisper).
Chapter 2
You can't reassemble what you can't name.
Each Max-Prop is individually balanced and matched. Never mix parts between propellers — even two of the same model. Learn the exploded view cold.
Chapter 3
The single step that saves the whole job.
This is the most important page in the manual. The Max-Prop will not tell you its pitch once it's apart, and the gears must go back exactly as they came out. Capture it all first.
Take a photo at every step — the prop as found, each part as it comes off, the gear and the timing marks, and any wear or damage. The photos go in the job file, to PYI with the pitch request (Chapter 6), and to the owner if anything is wrong. Free, and they save the job when memory doesn't.
Clean the grease off the aft face of the cone gear. Find the Y mark (a small drill hole in the spinner) and read which letter on the cone gear lines up with it. Write that letter down — that is the boat's current pitch setting. We confirm it against PYI's spec in Chapter 6 before reassembly.
Sources: PYI Max-Prop instructions; PYI 3-Blade Classic Removal Instructions; Max-Prop FAQ (Seaview/PYI).
Chapter 4
Apart, in order, without losing the timing.
With the pitch recorded and the gear witness-marked, take it apart deliberately.
Chapter 5
Seized on the shaft, bent pins, chewed gears.
A neglected Max-Prop rarely comes apart clean. Work patiently — the difference between a service and a condemned prop is how you handle a stuck one.
The hub or cone gear corrodes to the shaft taper. Use penetrating oil and gentle heat cycles, and a proper propeller puller on the hub with support behind it. Never hammer the blades or pry on the gear teeth to free it. If it still won't move, the shaft and prop may come out together for press work on the bench — don't destroy the prop forcing it in place.
The spacer pins that carry the blades can bend or shear from impact or a seized blade. Inspect each pin; a bent pin won't let the blade seat or feather correctly. Replace damaged pins / spacer with matched PYI parts — do not straighten and reuse a fatigued pin.
Inspect the cone gear and blade-gear teeth for rounding, pitting, chipped teeth, and excessive backlash (slop). Worn gears give sloppy pitch, chatter, and blades that won't hold their angle. Light, even wear may still serve; significant wear, chipped teeth, or heavy backlash → rebuild with PYI parts or condemn (Chapter 9).
After freeing and servicing, assemble and grease, then confirm all blades move together to the same angle and feather edge-on. A blade that lags or sits at a different angle means a timing error or a bent/worn part — fix it before the prop goes back in the water. Uniform feathering on every blade is non-negotiable.
Sources: PYI Max-Prop service guidance; Max-Prop FAQ (maintenance & repairs).
Chapter 6
Never reassemble a Classic to a guess.
Before a Classic goes back together, we confirm the correct pitch with PYI on every install. The recorded letter (Chapter 3) tells us what it was; PYI tells us what it should be for this boat and engine.
PYI Inc. contact — pyiinc.com / Yelp (Lynnwood, WA), confirmed June 2026. ESI process; Front Desk Manager course covers the customer-contact and job-file steps.
Chapter 7
Back together, timed, and tight — to the recorded pitch.
Reassembly is disassembly in reverse, with two things that must be exact: the nut and the gear timing.
Fit the hub (1) to the shaft on the key (3) — confirm the key is the right dimension and the hub seats fully (file the key slightly if it stops the hub short). Then the nut:
Set the central cone gear so the X mark (or your witness mark) lines up, then rotate the spinner so the Y mark lands on the PYI-confirmed pitch letter from Chapter 6. That sets the exact pitch PYI specced for this boat.
Fit the blades (9) onto the spacer pins (10), fill the end cap (11) with grease, and assemble. Once the end-cap screws are tight, give a few bedding blows to the spinner and blades with a plastic or wooden mallet to free the rotation, then lock each screw head with a 1/16″ stainless cotter pin. Then feel the blade rotation:
Source: PYI 3-Blade Classic Instruction Manual (assembly steps A–J, Fig. 2).
Chapter 8
Make it feather instantly and survive the season.
A Max-Prop lives or dies on grease and anodes.
Use the Max-Prop grease through the grease fitting — PYI specs Lubriplate 130 AA sea-water grease. Never use Teflon grease — it washes out fast. With each pump, rotate the propeller from forward to reverse so the grease works through the gear set and out, purging any water. Keep pumping until clean grease appears. Regrease at least every 2 years — or annually whenever the boat is hauled.
Protect the prop with zinc anodes on the propeller and shaft, and confirm the boat's bonding is intact. A neglected Max-Prop seizes and pits — and then it's a rebuild, not a service.
Out of gear, a well-greased Max-Prop feathers in a fraction of a second when you stop the shaft from freewheeling. If it's slow or stiff, it needs grease — or the rotation is too tight (Chapter 7).
Source: PYI Max-Prop instructions (greasing & anode guidance); Max-Prop FAQ.
Chapter 9
When a Max-Prop is done, say so.
Max-Prop hubs and blades are a bronze alloy. In a bad galvanic environment the metal degrades — and a degraded prop is a safety item, not a cosmetic one.
Dezincification is the zinc leaching out of the bronze, leaving copper-rich, porous, brittle metal. Tell-tale signs: a pink / coppery hue, a chalky or porous surface, and material that crumbles, flakes, or gouges easily. The part looks intact but has lost its strength.
It's driven by a spent or missing anode, stray current, poor bonding, or dissimilar metals in the water. Prevention is the same as Chapter 8: keep fresh zincs on the prop and shaft, and keep the boat's bonding intact. A well-anoded, well-bonded Max-Prop lasts decades.
Do not reinstall a propeller showing any of these — condemn it:
When it's borderline, send the prop to PYI for evaluation rather than guess.
Sources: PYI Max-Prop FAQ (maintenance/repairs); marine-bronze dezincification references.
Chapter 10
Bolt-on, bolt-pitch, and no haul to re-pitch.
The Easy and Whisper drop the Classic's gear-timing headache. They bolt onto the shaft like a fixed prop (mind the key dimension), and pitch is a bolt you swap — no haul-out.
The Easy adjusts pitch in 2° increments by changing a bolt for a different length. You can re-pitch without hauling — a real advantage when dialing in a repower.
The Easy can also change rotation (handy if a repower flips shaft direction). When a locking nut is replaced, fit it per PYI's procedure (Fig. 8) so it secures correctly.
Source: PYI Max-Prop Easy / Whisper Instruction Manual (fitting, pitch, rotation, locking nut).
Chapter 11
How we work is part of the work. This applies to every job.
Skill gets the job right; discipline gets it done profitably and hands the customer a boat that's better than we found it. These habits run through every ESI field job.
Before you walk to the boat, plan the job and gather the tools, parts and equipment you'll need. Think it through end to end and stage it. A planned job is a fast job; a forgotten tool is a trip you didn't have to make.
Use a cart for each job. Stage your tools, parts and consumables on it so everything travels with you to the boat and stays in one place — not scattered, and not back in the shop.
Every trip back to the shop is unbillable time the customer doesn't pay for and the job eats. Walking costs money. Keep your tools organized and within reach so you're working, not searching or fetching.
Count the extra trips you make to the shop and record those numbers. Trips per job, tracked over time, show where pre-planning is slipping and where we can tighten up. Honest numbers, every job.
No job is done until it's to spec, cleaned, and inspected by the lead. Leaving the engine room or cockpit dirtier than we found it is never acceptable.
ESI runs on Kaizen — continuous improvement. Small better-ways found on the boat, captured every day, compound into a faster, sharper shop. That only works if you write it down.
Final certification
A short check ran at the end of each chapter. Pass this final at 80% to unlock your certificate.