Boat propeller buying guide
Matching horsepower, material, pitch, and RPM for outboards and sterndrives from 90–400 HP
Stainless steel vs. aluminum
Stainless steel
- Thinner, stiffer blades — less flex under load means more efficient thrust
- Better hole shot and top-end speed, especially on heavier boats or with a stern drive
- Far more resistant to impact damage from rocks, sand bars, or debris
- Repairable/reconditionable rather than a total loss after a strike
- Holds up better in saltwater over the long run
- Costs roughly 2–4x more than a comparable aluminum prop
- Best for: bay boats, center consoles, offshore rigs, anyone running 150 HP+ or wanting max performance
Aluminum
- Lighter and more affordable — good entry point or backup/spare prop
- Flexes more under load, which softens the blow on a minor strike (bends instead of chips)
- Lower cost to replace if damaged, but performance loss is more noticeable
- Fine for smaller, lighter boats and lower horsepower ranges (under ~150 HP)
- Common OEM prop on new outboards as the standard-equipment option
- Best for: pontoons, small skiffs, lake boats, anyone prioritizing cost over top-end performance
Rule of thumb for your customers: under 115 HP, aluminum is usually a fine default. From 115–200 HP either works depending on budget and boat weight. Above 200 HP, most serious boaters step up to stainless for the efficiency gain and durability.
Horsepower, pitch & RPM reference by engine size
Pitch is the theoretical forward distance (in inches) the prop travels per one revolution. Lower pitch = more RPM and acceleration/hole shot; higher pitch = more top speed but slower acceleration. As a rule, each 1" of pitch change moves wide-open-throttle RPM by roughly 150–200 RPM in the opposite direction.
| HP range | Typical diameter | Common pitch range | Target WOT RPM | Notes |
|---|---|---|---|---|
| 90–115 HP | 13" – 14.5" | 13" – 19" | 5,500 – 6,000 RPM | Light/mid console boats and pontoons; aluminum very common here |
| 115–150 HP | 13.25" – 15" | 15" – 21" | 5,000 – 6,000 RPM | Crossover point where stainless starts paying off on heavier hulls |
| 150–200 HP | 14" – 15.25" | 17" – 23" | 5,000 – 6,000 RPM | Most popular range for bay boats and center consoles |
| 200–250 HP | 14.5" – 16" | 19" – 25" | 5,000 – 5,800 RPM | Stainless strongly preferred; hull weight and load matter a lot here |
| 250–300 HP | 14.75" – 16.25" | 19" – 27" | 5,000 – 5,800 RPM | Offshore and larger center consoles; four-blade options common for grip |
| 300–400 HP | 15" – 16.5" | 21" – 29" | 5,000 – 5,800 RPM | Twin-engine and high-performance rigs; stainless standard |
Ranges are general guidance across common outboard brands (Mercury, Yamaha, Suzuki, Honda) — exact pitch/diameter always depends on the specific engine, gear ratio, and boat weight. Always confirm against the engine manufacturer's WOT RPM spec.
Reading RPM to pick the right pitch
| Symptom at wide-open throttle | What it means | Fix |
|---|---|---|
| RPM below the engine's recommended WOT range | Prop is over-pitched — engine is overloaded (lugging) | Drop 1–2" of pitch |
| RPM above the recommended WOT range | Prop is under-pitched — engine can over-rev and lose torque | Add 1–2" of pitch |
| RPM in range but sluggish hole shot | Too much pitch or wrong blade design for the load | Try a lower pitch or a 4-blade for better bite off idle |
What "hole shot" means for your customers
Hole shot is how quickly the boat gets up on plane from a standing start. It's driven by blade count, cup, rake, and — most of all — pitch:
| Factor | Effect on hole shot |
|---|---|
| Lower pitch | Faster acceleration off idle, quicker to plane, slightly lower top speed |
| Higher pitch | Slower acceleration, higher top speed once on plane |
| More blades (4 vs. 3) | More bite and grip at low speed — better hole shot, especially with heavier loads (wakeboarders, pontoons) |
| Higher cup | Improves grip and reduces slip/ventilation in turns and rough water |