Product

Kaplan Style

are heavy-duty commercial propellers engineered exclusively for ducted propulsion plants and Kort nozzle applications. Featuring broad, squared-off blade tips designed to maintain an ultra-tight tip clearance against the interior wall of a nozzle shroud, the Kaplan profile virtually eliminates tip vortex losses while generating maximum bollard pull and low-speed thrust.

Broad, squared-off blade tip contours engineered specifically to operate inside Kort nozzles, eliminating tip leakage and maximizing hydrodynamic efficiency.

Delivers extreme pushing and towing power under heavy load conditions, providing maximum thrust-to-horsepower ratios for ducted commercial vessels.

Cast from high-impact CF3 (modified 304L) stainless steel or Nibral bronze to withstand log strikes, severe river silt abrasion, and cavitational erosion.

CNC-machined and dynamically balanced to ISO 484-2 Class 1 tolerances to eliminate shaft vibration, protect tailshaft bearings, and optimize fuel consumption.

Propeller Model Code	Blade Configuration	Diameter Range	Propulsion Material	Primary Commercial Application
KAPLAN-4B-CF3	4-Blade Kaplan / Ducted Profile	30" to 108"+ (Custom Pitch)	CF3 Stainless Steel (Impact Resistant)	Kort nozzle river towboats, push boats, and dredges operating in debris-heavy waters.
KAPLAN-4B-NIB	4-Blade Kaplan / Ducted Profile	30" to 108"+ (Custom Pitch)	Nibral Bronze (Ni-Al-Bronze)	Kort nozzle harbor tugs, commercial fishing trawlers, and heavy coastal workboats.
KAPLAN-5B-CF3	5-Blade Low-Vibration Kaplan	48" to 108"+ (Custom Pitch)	CF3 Stainless Steel (Impact Resistant)	High-horsepower ducted push boats requiring maximum bollard pull with minimal hull vibration.
KAPLAN-5B-NIB	5-Blade Low-Vibration Kaplan	48" to 108"+ (Custom Pitch)	Nibral Bronze (Ni-Al-Bronze)	Large ducted ocean-going tugs, research vessels, and heavy commercial transport craft.

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Design

Custom commercial ducted propulsion propeller featuring true Kaplan wide-tip geometry, zero or low-rake blade pitch distribution, heavy root sections, and specialized hub castings engineered for operation inside nozzle shrouds.

Application

Kort Nozzle Push Boats & Towboats: Multi-screw inland river vessels pushing heavy barge fleets through restricted channels.
Ducted Harbor & Ocean Tugs: Heavy commercial tugboats requiring maximum bollard pull for towing and ship-assist operations.
Commercial Trawlers & Dredges: High-load, low-speed commercial fishing vessels and dredges equipped with propeller nozzles.

Materials

CF3 Stainless Steel: Proprietary modified 304L stainless steel offering maximum impact toughness, high fatigue strength, and excellent weld repairability.
Nickel Aluminum Bronze (Nibral): High-strength marine alloy providing exceptional resistance to cavitational erosion and smooth hydrodynamic surfaces.

Construction

Precision Machined Hub & Bore: Custom SAE or Metric taper shaft bores CNC-machined and verified with calibrated plug gauges for precise fitment to the propeller shaft.
Anti-Singing Trailing Edges: Factory-beveled trailing edges engineered into blade tips to eliminate acoustic singing and underwater resonance inside the nozzle.
Dynamic Balancing: Dynamically balanced to ISO Class 1 specifications to prevent tailshaft stress, stuffing box wear, and cutless bearing failure.

Scope of delivery

Custom Kahlenberg Kaplan Propeller: Machined, polished, and balanced ducted propulsion propeller built to custom nozzle ID, pitch, and shaft bore specs.
ISO Class 1 Inspection Certificate: Pitch verification, blade thickness report, bore taper check, and dynamic balance certification.
Documentation: Installation instructions, shaft keyway alignment sheet, and Kahlenberg factory warranty paperwork.

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