590–750 mm — the big-boat series
Autoprop H9
For large sailing yachts, motor-sailers and displacement motor vessels with shafts to 2½ inches.
The H9's five diameters cover boats where a propeller is a serious casting — 60 ft ketches, heavy motor-sailers, passagemakers. Blade bearing loads are checked case by case against shaft RPM and power.
On displacement motor vessels, the self-pitching action holds the engine at efficient load across the whole speed range — the same physics that saves fuel on a yacht, applied to boats that motor all day.
Worth knowing: Above the H9 envelope (or ~350 hp) we move to custom engineering — same team, same verification, engineered case by case.
Specification
| Blades | 3 |
| Diameters | 590 · 616 · 630 · 686 · 750 mm |
| Shaft range | 40–65 mm (1¾–2½″) |
| Rotation | LH & RH (twin sets available) |
| Material | Manganese bronze, zinc/aluminium anodes |
Final diameter is engineered from your power, max RPM, gearbox ratio and tip clearance — never off a chart alone.
Sizing
Series is the easy part. Diameter is the engineering.
Power, max RPM and gearbox ratio give shaft RPM; shaft RPM and power give optimum diameter; your aperture sets the ceiling. The Builder runs it in a minute — an engineer verifies it before supply.
Get the verified recommendation for your boat
Tell us your boat, engine and how you use it — a propeller engineer replies within one business day with sizing checked against the fitment database.