Boat building materials and techniques have come a long way over the last couple of decades. The high strength cores and resin systems are key to a good boat structure. There was a time when sandwich core construction was considered fragile and unsuitable for high impact areas. The integral and blended structural stresses throughout the boat create a uniquely superior structure.
Many people don't realize how easy these materials are to work with. The computer-cut DuFlex panels allow for speedy results with a stylish finish.
The DuFlex panels are supplied with Z-join which is a quick way to create one large panel the full size of the boat. Picture shows panels joined with a timber batten each side clamping the join together.
An alternate option is to customise panels using core materials and laminate each side. This provides more flexibility in terms of engineering the structures to suit the particular application. For instance the core material could be optimized in style and density as well as the laminates chosen.
Structures can be either hand laminated or resin-infused. Resin-infusion is a superior process as the laminate is consolidated under vacuum and the resin to fibre ratio is usually much better due to the controlled environment.
The resin-infusion process now enables complex projects to be undertaken by 1 or 2 workers whereas traditionally requiring a half a dozen if wet hand laminating. Time can be taken to carefully place and position all the required materials before infusing. Picture above, is of a hull being infused, this hull takes approximately 20 minutes to fully infuse.
Composites can be used to substitute many traditional installations such as high load fittings, chainplates, rail and stanchion deck attachments, spars and numerous other applications.
Apart from superior strength these fittings also require no fasteners through the hull eliminating point loading and potential leaks which can also lead to core damage.Picture shows a composite bridle, striker and rail base fitting all faired and painted into the structure.
Curvesare easily achieved with what is called 'Kerfing', a technique of cutting a series of cuts part-way through the panel on the inside of the curved section.
Rounded flowing lines add that wow factor and provide a professional style finish.
Technology is making it possible for amateur builders to achieve complex structures and processes. Carbon fibre and other exotic reinforcements can be used to either enhance the structure in high-load areas or to minimize material and build hours. For example using carbon to replace E-glass can save approximately half the reinforcement and consequently the same amount of time.
Carbon fibre is ideally suited to spars which are loaded in compression. Carbon fibre can also be clear-coated to show off the decorative effect of the colour and weave. This is also something that can be easily done by the builder to create a show-piece on the boat such as a dashboard or steering wheel. These highlights can add a stylish and modern effect on the finish of your composite boat. Pictures shows moulded carbon steering wheel just de-moulded.
Compounded surfaces can also be built using flat core material. Pictured is a Spirited 380 cabin top which is plain foam sheet and then fastened down to the temporary frames below.
There is a limit to how much can be achieved using this method but the results can be surprising. Heat can be applied to foam core to bend even further however this can produce an inconsistent curve. Once the external surface is glassed and fully cured the panel can be removed to be glassed on the underside. The trick here is to either fasten frames to the part to hold its shape or was done here, glass the underside and replace on the jig before the underside is fully cured.
Strip-planking is a method synonymous with amateur boat builders and something that has also caused some headaches over the years. It is time consuming and requires a higher than average skill level. It is however an effective way of creating complex shapes such as hulls.
To strip-plank an entire hull will take considerable time and every plank is edge glued to the next. Once the planking is completed it is sanded down and glassed each side.
Picture shows an example of strip-planking the Spirited 380 composite forebeam and is the only strip-planking required on this project.
The sky is the limit to what can be built using composite material with fibres run in optimum ways to achieve the strength required. Even intricate hinge fittings as seen on our davits are built integrally using uni-directional fibres strapping each section on.
The finished item is seamlessly blended into the structure and painted to match the boat's finish.
Fairing can be something that amateur builders are terrified of and there is no doubt that this is a very important stage. This is the finishing touch to many hours of work and can either make it into a show piece or detract from the finish.
Something that always dictates the amount of fairing required is the standard of the building work. If this is not accurate and is reflected in the surface it adds material as well many more hours of fairing to rectify. However if the building work is accurate mostly what is required is some minor surface work such as fairing out glass laps. Pictured is a Spirited 380 needing fairing mostly to the join lines.
If a good finish is desired then there is no easy way other than using a sanding board. For the hull sides a meter long board is the minimum size required. Use 40 grit sandpaper initially to bring the filler down quickly, a tip here is to apply a coat of highbuild primer to the surface once you believe you are almost there. This can then be sanded down with the meter board using 80 grit sandpaper until you rub through it in places. This acts as a guide and will provide a clear indication of fairness.
Painting is another critical undertaking and something best left to a professional however with the correct equipment and some practice this can also be achieved by an amateur.
If painting a large boat then breaking up the surface into manageable sections is advisable. A tip is to start on a section that is least noticeable in case it is not as perfect as the rest.
Some consider building a boat using composites therapeutic and an expression of creativity.