21” Pitch U.S. Marine Outboard Boat Propellers 120 HP 1990 - 1991 L-Drive, Mercury 4-¼ Gearcase
You Are Viewing Available Prop Pitches For:
- Manufacturer: U.S. Marine
- Horsepower: 120 HP
- Years: 1990 - 1991
- Model: L-Drive, Mercury 4-¼ Gearcase Outboard
- Specs: Thru Hub Exhaust & 15 Tooth Spline
- Prop Pitch: 21”
Aluminum propellers are relatively inexpensive, easy to repair, and under normal conditions can last for many years.
Aluminum 3 Blade Propellers:
3 vs. 4 Blade Props
Diameter is the width of the circle that the prop would make when rotating.
Prop diameter does not affect the fit of the prop on a boat.
The diameter of your prop can vary by up to 1/2" with no discernable change in performance.
Caution: Before increasing the diameter of your prop, make sure there will be enough clearance between the blades and cavitation plate or anode on your engine.
Aluminum vs. Stainless Steel Props
2-Piece propellers consist of the outer prop housing and a removable center hub.
The removable hub easily slips into the outer piece, allowing you to have multiple props for different applications at a lower price. When the prop blades become worn or damaged they can be replaced while keeping the same hub piece.
2-piece propellers perform the same as the 1-piece/fixed hub versions.
Prices listed include both the housing and appropriate hub.
Both parts are added to your cart making it easy to find your complete propeller.