Propellers

Although the design and manufacturing process of today’s marine propeller has changed considerably, Kahlenberg has been designing and manufacturing marine propellers and propulsion systems continuously for over 100 years.  Specializing in propellers for commercial service, Kahlenberg currently offers a wide variety of fixed pitch designs made from stainless steel, nickel aluminum bronze (Nibral), and manganese bronze.

With modern design and manufacturing techniques, a standard “one size fits all” propeller design of constant pitch, fixed blade area ratio, and blade section profile, is less often used to achieve best performance.   Instead, custom designs using the most appropriate geometry are designed specifically for a given vessel and its operating conditions.  These custom designs reduce operating costs by being more efficient, and they are far more predictable with regard to performance than they have been in the past.

This is what Kahlenberg manufactures today:  Custom work boat propellers over 36” diameter, designed and manufactured using the latest technical advancements, built for superior durability in commercial service.

stainless steel work boat prop

Design

Determining the optimal propeller design starts with analyzing pertinent vessel data and the intended application of the vessel.  Using a combination of state of the art predictive software, previous experience, and reference to a historical database, Kahlenberg confidently specifies a propeller with the geometric properties best suited for your application.   Hydrocomp Prop Expert sizing software and PropCad software are utilized in the design process, with additional construction details modified as needed.  Experience is critical to achieve the best outcome of the design process.

stainless steel work boat prop

Manufacturing

The original geometric data from the design software is exported to 3D modeling software, where it is refined and output CAM (Computer Aided Manufacturing) software, for creation of toolpaths for CNC milling of a pattern.  This pattern is then used for accurate molding of the propeller at the foundry.  The seamless transfer of original design data to a finished propeller pattern saves countless hours of manual work and results in a casting far more accurate as compared to the traditional techniques of the past.

Kahlenberg Propellers are available in stainless steel, nickel aluminum bronze (Nibral) or manganese bronze.   Stainless Steel Propellers are primarily cast in a proprietary version of DOMESTIC CF-3 (304L) Stainless Steel, slightly modified to improve the corrosion resistance of CF-3 without sacrificing other advantageous properties including ductility and ease of repair that CF-3 is known for.  Propeller shaft bores are accurately machined and inspected by blue-fit to calibrated gauges assuring a minimum contact fit per ISO requirements.   Blade pitch is measured using Hale MRI scanning technology, (up to 56’’ diameter), or by other calibrated digital scanning equipment.   Final static balancing is done on precision rollers to within 1 ounce at the blade tips.

Inspection

Inspection processes are carried out at each step of the manufacturing process to the ISO 484/2 Standard in addition to ISO 9001-2008 inspection procedures established in-house.  Final inspection data is also verified with digital scanning equipment prior to shipment.  Kahlenberg Propellers for workboat service are held to ISO Class 2 dimensional tolerances, with pitch tolerances held to ISO Class 1 requirements unless otherwise specified.  These tighter manufacturing tolerances result in more accurately made, more efficient propellers that save fuel and enhance performance.  All propellers meet or exceed ABS Rules.  ABS, DNVGL, BV and various other certifications are available upon request.

stainless steel work boat prop inspection