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BMComposites

In an industry wedded to steel and aluminium construction, superyacht shipyards have been relatively slow to embrace composite materials for the manufacturing of large structures such as hardtops and biminis. But having completed more than 15,000 refit and repair projects, <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a> in Palma de Mallorca has proven the benefits of composites many times over.<img src="https://photo-assets.superyachttimes.com/photo/357903/image/large-a1b69eb8e595571c2355e9769bd52a3b.jpg" data-gid="gid://syiq/Photo/357903">In 2022 as part of a €35 million refit, the 73-metre <a data-gid="gid://syiq/Company/23" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Lürssen Yachts (Company)">Lürssen</a> <a data-gid="gid://syiq/Yacht/233" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Coral Ocean72.54m (237'12&quot;)Lürssen Yachts1994">Coral Ocean</a> (ex-Coral Island) designed by <a data-gid="gid://syiq/Company/17" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Bannenberg & Rowell Design (Company)">Jon Bannenberg</a> received an entirely new and enclosed sky lounge for entertaining and dining. The 140-square-metre roof structure replaced the former sat-dome area on the upper deck and comprised two large electric sliding sunroofs, as well as a new 3.8-metre navigation mast atop the roof. The whole massive structure was engineered and built out of composite foam-cored panels by <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a>.<img src="https://photo-assets.superyachttimes.com/photo/231707/image/large-671afdff72f522f8d6d98e20ccd34bff.jpg" data-gid="gid://syiq/Photo/231707">“The original idea was to do it in aluminum,” recalls Luke Hendy, technical &amp; commercial director at <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a>. “But we thought we could do something much better and bigger in composites, because we weren’t as constrained by the weight and stability issues of building in aluminium. What started out as a new roof turned into a major deck modification.”&nbsp;Local company 3D Tech was tasked with laser scanning the deck space to 0.2-millimetre accuracy and integrating the (often conflicting) inputs from the Gurit composite engineers and <a data-gid="gid://syiq/Company/161" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="H2 Yacht Design (Company)">H2 Yacht Design</a>, who drew the lines for the new sky lounge. The resulting 3D CAD model became the primary reference throughout the project lifecycle, from the tooling and component manufacture to the final installation.<img src="https://photo-assets.superyachttimes.com/photo/357899/image/large-f46a2494bf206d75ba42512286e7a962.png" data-gid="gid://syiq/Photo/357899">“Integrating all the HVAC, AV and electrics, as well as the big sliding doors and opening sunroofs, was part of quite a mammoth modelling operation,” continues Hendy. “But what we had at the end was a very accurate 3D model to start the tooling, which provides shapes that are much closer, if not identical, to the original design – much more accurate than working with aluminium, which has to be cut and welded, then faired and primed.”The roof and mast structures were manufactured off-site at the purpose-built <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a> facility and delivered in three main parts to <a data-gid="gid://syiq/Company/4473" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="STP Shipyard Palma (Company)">STP Shipyard Palma</a>, where they were assembled and then bonded and bolted to the top deck. Thanks to the accuracy of the CNC-machined female moulds, tooled directly from the CAD data, the composite parts required very little fairing compared to traditional aluminium construction. The use of 3D scanning at the outset further meant the huge components fitted perfectly. In fact, installing the structures took just two days with no hotworks required. The sky lounge was later described as the ‘jewel’ of the award-winning refit.<img src="https://photo-assets.superyachttimes.com/photo/357895/image/large-ce3ecad4097bab27985889c80bb422d4.jpg" data-gid="gid://syiq/Photo/357895">Weighing the cost&nbsp;Less fairing meant significant weight savings in a very stability sensitive area at the top of the yacht. Steel and aluminium usually require between six and eight millimetres of filler, which translates into eight kilos per square metre on average. That adds up very quickly in terms of weight, but also cost and time.“You also have to consider the logistics of tenting the yacht, the extraction, the disruption to other refit jobs and – critically – the time the boat is out of operation,” Hendy explains. “Instead, we built the structures off-site at our own manufacturing facility while everyone else cracked on with other works, then came back at the end of the six-month yard period and installed the new sky lounge already painted.”<img src="https://photo-assets.superyachttimes.com/photo/357898/image/large-cf3fae3ad31407605466acd9a87d953b.jpg" data-gid="gid://syiq/Photo/357898">To illustrate his point, Hendy references the recent refit of a busy charter yacht when <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a> were able to scan the whole upper deck overnight. This provided all the data they needed to go away and engineer, fabricate and paint a new composite structure for later installation. In the meantime, the owner could continue earning revenue from the yacht’s charter activities.&nbsp;“The raw material and basic construction costs may be marginally higher with composites, but over time it works out cheaper when you look at the wider picture,” says Hendy.<img src="https://photo-assets.superyachttimes.com/photo/183207/image/large-6c4f5ab23799f88a134a28946f0e9738.jpg" data-gid="gid://syiq/Photo/183207">Around the same time as <a data-gid="gid://syiq/Yacht/233" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Coral Ocean72.54m (237'12&quot;)Lürssen Yachts1994">Coral Ocean</a>, the 40-strong team at <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a> was commissioned to engineer, build and install new carbon-fibre hardtop biminis for <a data-gid="gid://syiq/Yacht/301" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="M577.6m (254'7&quot;)Vosper Thornycroft2004">M5</a>, the largest single-masted sailing yacht in the world. The new structures – two attached fore and aft of the existing transverse arch, and one covering the forward area of the huge flybridge – replaced the traditional steel tube and canvas bimini's with a more modern design featuring integrated AV and lighting and electrically operated sunroofs to protect the helmsman. Included in the upgrade was the manufacture of two new helm consoles and wheels to complement the new-look flybridge.<img src="https://photo-assets.superyachttimes.com/photo/183209/image/large-1f3592900ad62da0e6f4dec4df0909c6.jpg" data-gid="gid://syiq/Photo/183209">“We used the same 3D scanning, CAD modelling and CAD/CAM tooling techniques to produce the hardtops offsite for later transport to the <a data-gid="gid://syiq/Company/194" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="NCA Refit (Company)">NCA Refit</a> yard in Italy, but although the yacht was also composite in many ways the engineering proved more complex than <a data-gid="gid://syiq/Yacht/233" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Coral Ocean72.54m (237'12&quot;)Lürssen Yachts1994">Coral Ocean</a>,” says Hendy. “This was because we had to integrate the main bimini into the existing arch structure and visually the design by <a data-gid="gid://syiq/Company/6437" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Monk Design (Company)">Adriana Monk</a> was very sleek, so we had to be careful to achieve the stiffness we wanted without any vibration or resonance.”&nbsp;Reducing resonance&nbsp;This last point is critical in the engineering process. All physical structures have natural frequencies at which they will tend to vibrate when subjected to external forces, including waves and pressure pulses from propellers. These frequencies are dependent on the way mass and stiffness are distributed within the structure. Resonance happens when a dynamic force excites a structure to vibrate at its natural frequency – even a small force can produce a large vibration response that may result in ‘humming’. In the case of <a data-gid="gid://syiq/Yacht/233" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Coral Ocean72.54m (237'12&quot;)Lürssen Yachts1994">Coral Ocean</a>, <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a> referred to the yacht’s original noise and vibration studies to engineer the GRP/carbon sandwich panels to avoid these natural frequencies. Moreover, the PVC foam cores have much higher damping and thermal insulation properties compared to aluminium. <img src="https://photo-assets.superyachttimes.com/photo/357900/image/large-d767a68c94182e7c21c2b729c69b97cc.jpg" data-gid="gid://syiq/Photo/357900">One challenge that still has to be fully overcome by contractors like <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a> is that the class societies are more accustomed to dealing with steel and aluminium in superyacht construction. When faced with composites they usually to refer to the rules for guidance, but technology moves quickly and the existing regulations may be unsuitable. That can lead to situations where a surveyor might want to see a composite panel that has the same thickness as an aluminium one, because that is the benchmark he or she understands best.“One of the issues is that the regulations were originally written for commercial ships, so class is already playing catch up with the superyacht industry,” says Ian Heseltine, operations manager at <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a>. “However, on each project we work closely with class to help bring the rules up to date.”<img src="https://photo-assets.superyachttimes.com/photo/357902/image/large-dbc4db1256119fe2657abf37db086cad.jpg" data-gid="gid://syiq/Photo/357902">Full potential&nbsp;Indeed, Heseltine believes it is the high-tech nature of building with advanced composites that fundamentally distinguishes it most from metal construction. After all, you can design something sleek and curvy in aluminium, but then you have to convert the design into technical drawings to build it out of flat sheets of metal. At that point, you lose the direct connection between the design intent and the physical reality. Not so with composites:<img src="https://photo-assets.superyachttimes.com/photo/357901/image/large-66281726fe0b3e6f510983a7fcc68c0b.jpg" data-gid="gid://syiq/Photo/357901">“We bring 3D scans into our CAD software as the basis of the design, then build and test it virtually for rigidity and strength, resistance to wind loading and vibration, and so on,” explains Heseltine. “But we also use that very same CAD tech to create the tooling, which is able to reproduce a perfect impression of the original design intent. In other words, we harness the technology to its full potential from concept to completion.”Composite vs aluminumAluminium has a density of about 2.7 grams per cubic centimetre, whereas a composite foam-cored panel typically has a density of between 0.03 to 0.5 grams per cubic centimetre) with stiff outer skins of GRP, carbon fibre, or even aluminium. The core dramatically reduces weight while maintaining rigidity, making it much lighter than solid aluminium. In fact, a one-square-metre aluminium plate (5-millimetre thick) weighs approximately 13.5 kg, whereas a one-square-metre composite foam panel (with a 5mm core and 1-millimetre fibreglass skins) weighs 3-5 kg, depending on the skin materials.<img src="https://photo-assets.superyachttimes.com/photo/357904/image/large-6c0a129e610df5867b4de2d6c439e8f2.jpg" data-gid="gid://syiq/Photo/357904">Aluminium has good stiffness, but its rigidity comes from its density. Young’s Modulus (stiffness measure) for aluminium is about 70 GPa. Foam cores are not inherently stiff, but a panel’s stiffness comes from its outer skins (carbon fibre’s Young’s Modulus is up to 230 GPa) and the thickness of the sandwich structure. The foam core effectively increases the separation between the outer skins, which improves stiffness without adding much weight.Composite foam-cored panels have a much higher stiffness-to-weight ratio compared to solid aluminium plates. Indeed, for the same weight, foam-cored composite panels can be three to 10 times stiffer than aluminium, making them ideal for applications where light weight and rigidity are critical.<img src="https://photo-assets.superyachttimes.com/photo/357897/image/large-a92bb62ebf2a7af1d3ce69ab7fbffec9.jpg" data-gid="gid://syiq/Photo/357897">20 years in business<a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a> was set up in 2005 by sailor, boat builder and composites specialist Mark Branagh. After assisting the Oracle America’s Cup team in Valencia, he moved his headquarters to the <a data-gid="gid://syiq/Company/4473" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="STP Shipyard Palma (Company)">STP (Servicios Técnicos Portuarios) Shipyard</a> in Palma de Mallorca. Previously he had studied material science at Brunel University in London before working at <a data-gid="gid://syiq/Company/209" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Pendennis Shipyard Ltd (Company)">Pendennis</a> and <a data-gid="gid://syiq/Company/271" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Green Marine (Company)">Green Marine</a>, where he was involved in building composite sailing yachts such as <a data-gid="gid://syiq/Yacht/539" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Wally B32.72m (107'4&quot;)Pendennis Shipyard Ltd1998">Wally B</a> and <a data-gid="gid://syiq/Yacht/1784" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Kenora32.72m (107'4&quot;)Wally1999">Kenora</a>, <a data-gid="gid://syiq/Yacht/788" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Ghost37.25m (122'3&quot;)Vitters Shipyard2005">Ghost</a>, <a data-gid="gid://syiq/Yacht/1293" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="Sojana34.97m (114'9&quot;)Fast Cruising Ltd2003">Sojana</a> and Playstation. Mark and Luke Hendy met in Falmouth in the early days of Pendennis. After spells at <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">Composite Works</a> in <a data-gid="gid://syiq/Company/5375" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="La Ciotat Shipyards (Company)">La Ciotat</a> (now <a data-gid="gid://syiq/Company/547" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="MB92 La Ciotat (Company)">MB92 La Ciotat</a>) and running his own business, Luke joined <a data-gid="gid://syiq/Company/7202" href="#managed-by-system" rel="noopener noreferrer" target="_blank" title="BMComposites (Company)">BM Composites</a> as an acting partner in 2008, a role that was only formalised in 2023. In 2018 they opened a state-of-the-art workshop facility in Son Moro in Mallorca. Today, the company employs over 40 project managers, designers and composite technicians.This article was first published in <a href="https://www.superyachttimes.com/magazine/how-to-build-it-issue-7" target="_blank">Issue 7 of &nbsp;</a><a href="https://www.superyachttimes.com/magazine/how-to-build-it-issue-7" target="_blank"></a><a href="https://www.superyachttimes.com/magazine/how-to-build-it-issue-7" target="_blank">How to Build It</a> <a href="https://www.superyachttimes.com/magazine/how-to-build-it-issue-7" target="_blank"></a><a href="https://www.superyachttimes.com/magazine/how-to-build-it-issue-7" target="_blank">magazine, which can be downloaded here</a>.

BM Composites and the rise of advanced materials

Justin Ratcliffe investigates  BM Composites in Palma de Mallorca, which have completed more than 15,000 refit and repair projects. 