The nine meter long fiber glass hull and deck sections of the Scorpion 85 RIB are both manufactured using Scott Bader’s Crystic VE679-03PA vinyl ester infusion resin, infused using a Ciject One resin mixing and dispensing production machine and vacuum system supplied by Composite Integration Ltd. Tygavac Advanced Materials Ltd supplied the consumable infusion materials and provided training in bagging techniques to the Scorpion team. The overall Scorpion 85 infusion project was coordinated by Scott Bader.
Scorpion RIBs, based at Lymington on the south coast of England, is now a world leader in the manufacturing of rigid inflatable boats for the premium leisure marine, super yacht and commercial markets. Established in 1996, the company quickly gained a reputation for the high build quality and excellent performance of its RIBs.
Matched marine approved laminate
The hull and deck laminate system for the Scorpion 85 is a Scott Bader ‘matched marine system’ which uses Lloyds approved materials: Crystic 65PA gelcoat; Crestacoat 5000PA barrier coat; and Crystic VE679-03PA infusion back up resin. This Crystic matched marine laminate system provides a high gloss gelcoat finish, with proven long-term performance in use. Glass fibre reinforcements are used in the hull, with grooved infusion grade PVC foam cores additionally specified in the deck. Areas of the deck and hull are also bonded with Crystic Crestomer structural adhesives to save weight and avoid print through, especially in the hull; print-through is a common problem if hull joints for bulkheads and stringers are over laminated instead of bonded. Kevin Hunt, general manager of Scorpion RIBs Ltd commented: “We have used Scott Bader resins and gelcoats since we started the business 17 years ago. Today 99 percent of what we use to fabricate our high performance RIBs are Crystic products, which have proved consistently reliable for long-term build quality. We also greatly value the expertise and technical support we get from Scott Bader.”
Switch from hand-lay up to infusion
During 2012 Scorpion RIBs moved into a new state-of-the art manufacturing facility. The management team at Scorpion recognized the benefits of using the latest vacuum infusion processing techniques and systems to improve build quality, increase productivity and enhance shop floor health and safety conditions; traditional hand lay-up processing techniques have been used by Scorpion since the company first started. The decision was taken in 2013 to begin the switch over in production to using a state-of-the-art infusion system. Infusion technology experts from Scott Bader’s Technical Service team were initially brought in and consulted about suitable marine approved infusion resins, best practices and current infusion technology systems available.
Meter-Mixing machine infusion technology
Scott Bader recommended Scorpion RIBs to use a Composite Integration Ciject meter-mixing infusion machine and vacuum pump system alongside its on-site processing technical assistance. The recommendation was based on previous highly successful vacuum infusion projects which both companies have worked on together. This included a major project at Princess Yachts International, infusing in one shot the 32 metre hull of its M–class super yacht. As the super yacht market is a growing key customer base for Scorpion RIBs used as support craft, it was a logical decision to use the same infusion production techniques to achieve a similar high level of build quality expected by super yacht owners.
The use of meter-mixing injection equipment has been pioneered by Composite Integration for several years, aimed primarily at eliminating the risks and challenges faced by composite fabricators looking to reliably and cost effectively mould a quality FRP part on any significant scale. The marine and wind energy markets in particular have recognised the need to use meter mixing for vacuum infusing large composite structures up to 40 metres long to avoid major production quality problems such as resin mixing consistency and bulk-exotherm, as well as eliminating high levels of waste.
At the simplest level, the key benefit to a fabricator of using a meter-mixing type infusion machine alongside vacuum pumps is that it provides a simple, reliable way for an operator to consistently maintain a constant level of mixed resin in the feed tank from which the infusion pipes positioned in the mould are fed. This in turn ensures that a sufficient volume of mixed resin is available to provide a continuous, uninterrupted resin flow at the required rate through the feed pipes for the size of moulding being infused. More sophisticated, automated process controls can be added by Composite Integration to standard Ciject machines, such as ultrasonic resin level sensing which can automatically stop/start the machine to automatically maintain a constant mixed resin level in the feed tank.
Direct resin injection capability
With further automation and increased productivity to meet growing demand in mind, Scorpion RIBs decided on the Composite Integration ‘Ciject One’ machine as this model offers an added level of automated process functionality linked directly to a mould. Pressure sensors positioned strategically in the mould feed-back data during infusion to the injection machine. This functionality avoids the use of any open resin container since the ‘intelligent pressure control’ system built into the Ciject One model automatically controls the supply of mixed resin at an optimum metered rate directly into the mould. This has the added advantage from a VOC health and safety standpoint of being a ‘fully closed’ FRP moulding process.
The production team at Scorpion did not opt to use the direct injection functionality for the first Scorpion 85 hull and deck mouldings. However, as a second phase, after further training and gaining more confidence in using the Ciject infusion machine, the objective is to do so in the future to gain all the benefits of direct resin injection. These benefits include key factors for premium quality manufacturing such as: process repeatability due to built-in systemisation for operators of each process stage; avoidance of resin mixing inconsistency and bulk exotherm problems, process data capture and recording for each moulding.