Technical data:

• What was needed: A racing sailboat that floats above the water surface by converting the water pressure
• Requirements: 100% lubrication and maintenance-free, no interference from seawater, dynamic movements, resistance to the required load, smooth running, low weight, easy assembly
• Products used: dryspin® trapezoidal lead screw nut, igubal® rod end, iglidur® J plain bearing bush
• Success for the customer: The lead screw nut, plain bearing and rod end installed by igus® guarantee low friction coefficients for the necessary sliding of the upper joint, dampen the vibrations transmitted by the rudder and, compared to their metallic counterparts, do not require any lubricants and are easier to clean from salt residues from the sea.

Students at the Polytechnic of Turin build racing sailboats with wing profiles. The pressure exerted by the water on the profiles causes the boats to float, reducing the friction of the hull and allowing the drive force of the wind to be fully utilised. One of the systems developed is the rudder holder. It enables sailors to adjust the angle of attack of the profile at the end of the rudder and thus immediately guarantee the desired lift under the respective racing conditions.

The most important challenges that had to be overcome during the design phase were

• To avoid degradation of the system due to the marine environment and dynamic conditions of motion
• Components that can ensure the correct conversion of the rotary motion into a linear motion
• A system of bearings and flange bushings to support the linear movement of the bolt to ensure low friction coefficients at the interface to maintain the contact surfaces
• The correct kinematic movement between the set screw and the rudder stock through joints that accompany the desired angle of inclination and sliding. Other key design factors related to the team's objectives are: Limiting the weight and complexity of the components used and the environmental compatibility of the system in general

A dryspin® lead screw nut was installed, which converts the rotary movement of the pulleys into a straight-line movement of the steel pin. The most important specifications required are Correct coupling with trapezoidal thread of a steel pin, resistance to the required load, smooth running and no deterioration of the thread of the pin, which does not lose its specification in humid and salty environments. Flange bushings are also used which, when mounted on the fittings, support and slide the pin in smooth sections. Main features: Resistance to the slow but repeated sliding of a steel rod with radial and axial dynamic radial and axial loads and low coefficients of friction. The third element is the ball and socket joint, which allows the rudder stock to be inclined relative to the horizontal displacement of the threaded pin. Main requirements: Enabling rotation, inclination and sliding of the vertical rod, which is fixed to the rudder, with low coefficients of motion.

All parts used igus® are resistant to humid and salty environments. No lubricants are required, they are lightweight and easy to install and maintain.