Raku Kit Construction


All of the Raku cats are designed on detailed electronic models that allow us to produce files for 2D and 3D CNC, additive manufacture (3D printing) and other technologies that will come to the fore over time to make the build process faster, cleaner and hopefully a lot more environmentally sustainable.

Once the model is finalized the panel definitions for all of the composite parts are created and panels are trimmed as necessary to provide offsets for hull thickness and panel overlaps. Each panel gets an identifying number so it can readily identified by the builder and traced back to the model if any discrepancies arise.


Most of the construction process is very straight forward but in more complex areas where there is a potential for some confusion we provide assembly drawings to assist with the build.

The plans are presented in pdf format on A1 size drawings, but they can also be printed A3 size to fit an A3 clear sleeve display book.


DuFLEX kits are manufactured in Australia and distributed world wide by ATL Composites.


DuFlex Kits for the European market are manufactured by VDL Composites in Germany


DuFLEX panels are PVC foam cored with glass skins laminated under pressure in West System epoxy. Panels are joined with ATL's proprietory Zed Join system. For a step by step description of the build process with DuFLEX kits see the catamaran kit build process in the LAB


DuFlex kits can be engineered for CE Compliance on request. 



Hull shoes are built over temporary male formers for strip planking or a batten mould for sheet foam. It is possible we will have fully moulded hull shoes available for some of the Raku designs in the near future.

Cabin Top Construction

The cabin sides, the fwd window panel, and the chamfer between the cabin sides and the cabin top are all made from  developable panels with no compounding required.

However the cabin top has a little bit of compounding. That means we can't produce a perfectly accurate shape in 2D because we have to flex the materials to achieve the compound curves.

No problem. We can get it very close so it will require a minimum of trimming on the building frames.

Why do we use compound curvature in the cabin top (and in most cases the decks also)?

Because a flat cabin top on this style of boat looks compromised - it will denote your boat as an amateur build regardless of the high standard of craftsmanship that goes into the construction.


Achieving the compounding is not difficult. Our recommendation is to make the cabin top over male formers from panels only glassed on the inside. Fit the cabin sides and fwd panel to the formers (they can be glassed both sides), bend the cabin top panels onto the frames and glass the cabin top with an overlap to the side panels. Fit receiving cradles to the cabin top and flip the entire cabin. Fit the cabin top support beams, finish any tabbing, fit electrical conduits as required and complete final fairing before fitting to the hulls and decks.

Note that it may be possible to achieve the required compounding in the cabin top panel with the internal and external glass skins in place, possibly with the aid of a couple of kerfs in line with the support beams but if you are reluctant to experiment we advise the foregoing procedure as a precaution. 



Panels to make strips for planking the Hull Shoes

Hull Topsides

Underwing Chamfers

Wingdeck (flat and fwd bullnose)


Hull to Deck Chamfers



Daggercases or Fixed Keels

Forebeam Panels

Longeron Standard Length

Cabin Soles and Berth Berth Panels

Full Set of BH's Standard Layout

Includes Centre Bathroom in Stbd Hull



Floors for Lockers in Bow

Cockpit and Transom Panels

Aft Beam


Support Beam under Wingdeck

Cabin Roof Support Beams

The composite panels are set out in five different laminate specifications

The different shades of grey indicates a different laminate.


CNC'd formers for hull shoes. One set. 

Panels to make four support cradles for the hulls.

Temporary formers for the cabin top..


Central bathroom in stb hull is included with the standard ki for Barefoot 40 and larger designs. It can be deleted from the kit if not required.

Plan view of the steps down from the saloon. there is no divider panel in the middle of the bathroom in the standard kit but it can be ordered as an option.

Central bathrooms Port and Stbd showing an additional divider panel in the Port bathroom (LHS)

The centre bathroom panels fit on four sheets. One bathroom is included in the standard. You can remove it or  add a second on ordering the kit and the cost will be adjusted accordingly. 


There are three options for purchasing materials for the saloon interior.

1. Purchase the plain panels as an add on to the kit, design and manufacture your own interior furniture,

2. Purchase the CNC'd kit for either layout- Classic or Open.

3. Design your own custom layout and have it supplied with the rest of the kit.

The Classic and Open Layouts use the same number of panels.

There are various materials available for the interior kits but we generally recommend H60 PVC core (12mm or 15mm) and glass skins for ease of working and bonding the corners.

Standard bench height is 950mm. We can customise that if you prefer up or down.


Settee fwd to port, galley benches to stbd, nav., entertainment to port (lower left).



Crash pad/lounge to port (LHS of image), nav, stn. (top) and galley bench (RHS).

Mast post is not part of the interior kit.


Strips of PVC foam with carbon unis both sides as planking for a 42' trimaran hull
Strips of PVC foam with carbon unis both sides as planking for a 42' trimaran hull

The most popular method used in conjunction with panel kits is strip planking, usually with PVC foam planks that have been laminated with a light layer of unidirectional glass or carbon.

The foam panels are joined end to end to the full length of the hull and laminated both sides with the fibres parallel to the length of the hull. Then the panels are ripped into strips of varying width depending on the degree of curvature in the hull. When the planking is completed the surface is faired and a second laminate is applied both sides to complete the structural requirements.

Optional Planking materials:

1. Western Red Cedar

2. Duflex Strips: PVC cores with Hoop pine veneers both sides. More pleasant to work with than glass laminates and doesn't blunt the saw blades so quickly.

We advise against using balsa cores.


1. Batten mould:

Temporary mould frames are set up and then battens run at approximately 150mm centres.  PVC foam sheets are then laid over the stringers and the skin laminates applied over the external surface after the foam core is in place. The internal surface is laminated after the hull is turned and released from the mould frames.


2. Male Plug.

Many professional builders prefer to to build a solid male plug and vacuum laminate over the plug. This method is more attractive if a number of boats are to be built to the same design.


Note that both of the above methods require that the mould frames be offset for the thickness of the mould material (the battens in case 1. or the plug planking material in case 2.)  as well as the actual hull planking, whereas for strip planking the mould frames or permanent BH's in the setup are only offset for the hull planking.

This needs to be considered when ordering plans.


Foam Sheets over a Batten mould. Thanks to Julian Griffiths for the photo.


There is a wide range of rig options available for the Raku cats including alloy or carbon, rotating or non rotating, wing mast or conventional oval section, and for each one of the above there is a range of options for supporting the rig, both in geometry and in materials.

This is a field for specialists and the choice will involve decisions based around price, weight, stiffness and ease of handling.

If you need help with decisions on the rig we recommend you strike up a dialogue with one or more rigging specialists. 

See also the article on our web site here: www.graingerdesigns.net/lab-library-2/rig-selection-guide/


Standard Bow Prod is same length as hulls so you don't get lumbered with berthing fees for a longer boat. The bow prod is self supporting, requiring no brace wires for support.

Extended Bow Prod provides added sail area upwind and cleaner flow over the headsails.

It can be made from a one piece beam incorporating the transverse forebeam, or alternatively an extension piece that fits a socket in the end of the main beam.


You are at full liberty to go to your own sources for rigs, sails, deck hardware, electronics and all of the equipment required to fully equip your Raku, and we are happy to provide your chosen suppliers with the drawings and specifications they need to price your project.


We are also happy to recommend products and services from companies and professionals we have worked with over the years and who have provided our customers with good products, sound advice  and support when needed.