Production of precision engineering mainsail batten cars in titanium alloy

Production of precision engineering mainsail batten cars in titanium alloy
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Introduction

The aim of this case study is to illustrate the construction of precision engineering mainsail batten cars on behalf of Gruppo Perini Navi Spa of Viareggio, the world-leading designer and manufacturer of sailing and motor yachts.
Gruppo Perini Navi ranks among the top international names in the world of high profile sailing and CRP Meccanica was chosen to work alongside it as its technical partner. CRP Meccanica is part of CRP Group from Modena, and is specialised in high precision CNC machining for applications in the motorsport, automotive, aviation and naval industries. Its ability to offer readily employable mechanical solutions is the guarantee of quality and efficiency and is confirmation of its strong competitive edge.
Its machining department uses latest generation, 5-axis CNC milling centres that are particularly ideal for the machining of high-tech materials, such as titanium alloys, Metal Matrix and special steels.
In this specific case, Perini Navi SpA, one of the leading firms that builds yachts in excess of 45m, confided in the experience of CRP Meccanica for the production of mainsail batten cars.

Construction of mainsail batten cars in Titanium Ti6Al4V for high end sailing vessels

The aim of the project was the construction of mainsail batten cars capable of preventing the sail from tearing.
The mainsail [1], or mainsails in the case of large sailing yachts with two masts, usually has carbon fibre battens running across it, whose function is to ensure the sail keeps its aerodynamic shape. These battens run from the leach edge of the sail to the mast and are inserted into pockets sewn onto the sail itself. An aluminium track fitted into the mast provides the connection between the sail and the mast.

Because of the curved design of the leach, the battens are subjected to compression as they strain to keep the sailcloth taut and this compression increases as the wind increases when the yacht is at sea.

As a result, the cars fitted at the end of the battens are also subjected to compression whose force can reach up to 2 – 3 tons. This force is transferred to the aluminium track that secures the sail to the mast.

Production of precision engineering mainsail batten cars in titanium alloy for the high-end yacht sector

Production of precision engineering mainsail batten cars in titanium alloy for the high-end yacht sector

Precision engineering mainsail batten cars in Titanium alloy

The development of this system with cars was essential in order to prevent sail wear and subsequent damage near the end of the pockets containing the battens (the area close to the mast).

Production of precision engineering mainsail batten cars in titanium alloy for the high-end yacht sector

Sailcloth damage caused by changes in load

This damage is the direct result of sailcloth wear caused by changes in load transferred from the battens to the final part of the pocket during sailing manoeuvres. Using batten cars guarantees this load will be transferred from the battens to the cars, without putting any local strain on the sail, thus eliminating sailcloth wear and the need for typically long and costly repairs for large sails (400 – 450 m2 and weighing in at over 500 Kg).

CRP Meccanica chose a lightweight but durable material for this type of product, namely Ti6Al4V titanium alloy, which is not only a noble material, it also is a guarantee of structural strength and significant resistance to corrosion, a pivotal factor for marine applications.

The Titanium alloy used by CRP Meccanica for the production of its cars also satisfies the need to have parts that comply with weight- and size constraints.

The complexity of these parts has made it vital to use cutting edge precision engineering machinery: Perini Navi recognised the superior level of technological expertise at CRP Meccanica, the direct result of its origins in the world of motorsport, an extremely demanding field that expects a level of reliability and precision out of the ordinary.

This is why the work at CRP Meccanica becomes fundamental for any application involving a certain degree of criticality, like the specific case of the cars designed for Perini Navi sailing yachts. The cars in question also incorporate inserts made of a plastic material designed specifically to facilitate the sliding of the cars inside the track.

Production of precision engineering mainsail batten cars in titanium alloy for the high-end yacht sector

Car in Ti6Al4V Titanium alloy

Details of the CNC machining of the mainsail batten cars

The cars are made using 5-axis milling centres, machinery that is particularly ideal for working hi-tech metals such as Titanium alloys, Metal Matrix and special steels.
CRP Meccanica is specialised in the production of components in MMC and Titanium.
CRP Meccanica chose Ti6Al4V titanium alloy for this type of application because of its mechanical properties combined with its extremely light weight. Because of its specific features, this material is widely used in fields such as top of the range boatbuilding, where durability, performance, reliability and most of all resistance to corrosion and structural resistance are essential. Titanium is immune to the corrosive effects of seawater and so it is also widely used for the production of parts and components for seagoing vessels, as in this case. It is also capable of supporting extreme temperatures; because of its low density, it is a particularly light material yet twice as hardwearing than aluminium. As far as the construction of components for Perini Navi is concerned, the size and shape of the cars demanded the use of small yet very long milling tools to accommodate the very tight fillet radiuses. EDM machinery and hard metal tools were used for machining. The end result is tangible proof of the high precision of the parts and the prime aesthetics made possible because of the technology and experience offered by CRP Meccanica.

Conclusion

The international scenario demands a company vision that acknowledges the importance of innovation and CRP Meccanica has risen to the challenge of globalisation by focusing on the ongoing updating of its technological knowhow.

Production of precision engineering mainsail batten cars in titanium alloy for the high-end yacht sector

Perini Navi Spa Yacht fitted with cars made by CRP Meccanica

The know-how of CRP Group that includes CRP Meccanica, is enrooted in the experience gained in over 40 years in the world of motorsport. Its ability to offer cutting edge technological solutions and innovative materials puts it in an ideal position to offer its customers the assurance of quality, reliability and accuracy.

CRP Meccanica works with latest generation materials to make functional and aesthetic parts for customers such as Perini Navi SpA, the world leading designer and builder of luxury sailing yachts, with the aim of making bespoke parts in a rapid timeframe, by exploiting the full benefit of its specialised in-house technical team, which is involved in projects every step of the way.

There is no doubting the emotional impact of sailing: it puts man face to face with the power of nature and the supremacy of the sea. This is why building boats that are the stuff of dreams becomes an art, and as such it demands the experience of suppliers like CRP Meccanica, capable of accompanying the customer until the project has been completed to plan and on schedule, supported by its engineering team for the entire duration of the job.

Like the world of motorsport, nothing is left to chance in the world of high end sailing, so interiors, accessories and the mechanical details must not only have a specific function, they must also look fabulous. Over the years, this sector has become an industry where business skills combined with passion and professional expertise have become success factors, and choosing the right technological partner is fundamental to ensure the successful outcome of a project.

 


[1] The mainsail is the tall sail on the yacht and it is mounted on the mast.