Hydrofoil Stabilizer – Fits Outboard/Stern Drive Motors 40-350 HP (Replaces PMJR71B, XRmarine Sport-300)
Hydrofoil Stabilizer – Fits Outboard/Stern Drive Motors 40-350 HP (Replaces PMJR71B, XRmarine Sport-300) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
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Hydrofoil Stabilizer – Fits Outboard/Stern Drive Motors 40-350 HP (...
Hydrofoil Stabilizer – Fits Outboard/Stern Drive Motors 40-350 HP (Replaces PMJR71B, XRmarine Sport-300) is backordered and will ship as soon as it is back in stock.
Product Details
This marine whale tail Hydrofoil Stabilizer – Fits Outboard/Stern Drive Motors 40-350 HP (Replaces PMJR71B) is designed to improve boat handling, enhance thrust, reduce planing time, and keep boats on plane at lower speeds. It is compatible with a wide range of outboard motors and stern drives in the 40-350 HP range.
This part is a direct interchange for SeaSierra PMJR71B and XRmarine Sport-300.
- Installation Method: Bolt-on (requires drilling)
- Mounting Location: Direct mount to the engine's cavitation plate
- Material: Constructed from UV-resistant, marine-grade nylon for durability
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| SeaSierra | PMJR71B |
| XRmarine | Sport-300 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model Type | Rated HP | Stroke | Notes |
|---|---|---|---|---|
| Mercury | Outboard Motors | 40-350 HP | 2- & 4-Stroke | |
| Yamaha | Outboard Motors | 40-350 HP | 2- & 4-Stroke | |
| Johnson | Outboard Motors | 40-350 HP | 2- & 4-Stroke | |
| Evinrude | Outboard Motors | 40-350 HP | 2- & 4-Stroke | |
| Honda | Outboard Motors | 40-350 HP | 4-Stroke | |
| Suzuki | Outboard Motors | 40-350 HP | 4-Stroke | |
| Tohatsu | Outboard Motors | 40-350 HP | 2- & 4-Stroke | |
| Mercruiser | Stern Drives | |||
| OMC | Stern Drives | |||
| Volvo | SX-A, DPS, DPR, DPH, 280, 290 series | Requires longer bolts and 1" fender washers (not included) |
Note: Not compatible with Volvo Ocean Series XDP stern drives.
Technical Specs
- Product Type
- Hydrofoil Stabilizer
- Installation
- Bolt-on (requires drilling)
- Connection
- Direct mount to cavitation plate
- Housing Material
- Marine Grade Nylon PA66 Plastic
- Housing Color
- Red
- Dimensions
- H: 17 inches (431.8 mm) × W: 14.4 inches (365.8 mm)
- Fitting Type
- Bolt-on with included hardware
- Other Technical Attributes
- UV-resistant marine-grade material
What’s in the Box
- 1 × Hydrofoil Stabilizer
- 4 × Sets of Stainless Steel Screws and Nuts
- 1 × 6.5mm Drill Bit
- 1 × Installation Instructions
Installation Notes
- Ensure the engine is off and the boat is safely secured on a trailer or lift.
- Center the hydrofoil on the top side of the cavitation plate. Ensure it does not interfere with the propeller's movement.
- Mark the four drilling locations on the cavitation plate through the mounting holes of the hydrofoil.
- Remove the hydrofoil and carefully drill the marked holes using the included 6.5mm drill bit.
- Place the hydrofoil back on the cavitation plate, aligning it with the newly drilled holes.
- Insert the stainless steel screws from the top and secure them from the bottom with the nuts.
- Tighten all nuts evenly and firmly. Do not overtighten to avoid damaging the cavitation plate.
- Before launching, double-check that the hydrofoil is secure and does not obstruct any moving parts.
Troubleshooting & FAQ
Will this hydrofoil fit my specific motor model?
This hydrofoil features a universal design for most outboard and stern drive motors in the 40-350 HP range. To ensure a proper fit, measure your engine's cavitation plate and compare it with the hydrofoil's dimensions of 17 inches by 14.4 inches to confirm adequate clearance and surface area.
Is drilling into my engine's cavitation plate required?
Yes, this is a bolt-on stabilizer that requires drilling four holes in the cavitation plate for a secure and permanent installation. This method provides the most stable and effective connection. All necessary mounting hardware, including a drill bit, is included.
What performance benefits should I expect?
Properly installed, the hydrofoil will help your boat get on plane faster, which reduces bow rise and improves visibility. It also allows the boat to stay on plane at lower speeds, leading to improved fuel economy, and can enhance stability and reduce porpoising or chine walking.
How does this compare to a factory-installed stabilizer?
This aftermarket hydrofoil is designed to offer performance benefits similar to or exceeding those of OEM options. It is engineered from durable, UV-resistant materials to withstand the marine environment and provides a cost-effective way to improve your boat's handling and efficiency.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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