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Engineered by Composites Consulting Group (CCG) to Category A Offshore, the R42 designed by Tony Grainger,  is the latest high performance trimaran under construction at Australian Custom Multihull Yachts at The Boatworks on Queensland’s Gold Coast.

LOA 12.80 m
Main Hull - Beam OA 3.55 m
Beam DWL 1.06 m
Sailing Weight Approx 3,500 - 3,700 kg
Grainger Designs www.graingerdesigns.net
ACM Yachts Australian Custom Multihull Yachts
Design Concept

A project that explores the boundaries between a high performance cruiser and a lightweight racer, the R42 deploys a fine main hull with just enough concession to creature comforts below decks to ensure that planning a long term cruise, is as equally realistic as mixing with the action at the front end of the fleet in a major race series.

The R42 is custom designed to a well thought through design brief from an experienced Australian trimaran owner.


The mould frames and strongbacks are made from 16mm MDF that were CNC machined by ATL Composites from electronic cutting files. The cutting files provide slots for fast assembly and the building forms are stabilised by locking the joints with epoxy fillets. The beams are symmetrical about the athwartships axis, so one set of female tools can be used to build all of the beams. The primary beam is a box structure that sits inside the fairings. The fairings are non-structural, so the laminates are quite light.

The main hull planking material is made with DuFLEX Composite Panels with a 15mm Divinycell H80 structural IPN foam core with 200grm carbon unidirectional laminate on each face.  The DuFLEX panels are manufactured under heat and positive pressure by ATL Composites to ensure a consistent laminate with a high fibre ratio. The panels were supplied in 1200mm x  2400mm sheets with the proprietary DuFLEX Z-joint on each 1200mm end.

The panels are bonded with Techniglue R60 structural adhesive, supplied in cartridge packs, using ATL's  Z-Press which applies pressure and heat to the join, allowing the epoxy to cure in just a few minutes.  The panels are progressively moved along until a panel of the full length of the hull is created. The full length panels were then ripped into strips of varying widths and planked over the temporary frames to make the hull shell. 

The planking has been reinforced with a combination of carbon fibre double bias reinforcements laminated with the high performance KINETIX R246TX Thixotropic Laminating epoxy under vacuum to achieve a high fibre to resin content to optimise the construction for weight and stiffness.

In the more compound sections of the main hull, Divinycell H80 foam in a variety of thicknesses has been used to create the shapes, while H100 and H200 was used intermittently in specific high load areas,  and then laminated in-situ with R246TX and a combination of KINETIX H160 Medium and H126 Super Fast Laminating hardeners

The hull has been faired with Technifill XP R1160, a lightweight, pre-thickened compound that is easy to sand with no shrinkage.

Launched October 2019

More photos of this project can be viewed on  https://www.graingerdesigns.net/trimaran-designs/r42-trimaran/r42-build-gallery/

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