Yachting has an enduring love affair with teak, but for how much longer? Shrinking stocks of wild forest teak, an industry-wide sustainability drive and the first criminal convictions for the illegal importation of Myanmar teak, are pushing shipyards to seek out wood alternatives.

Disclaimer: Although synthetic or composite decking materials are widely available, due to space limitations this article focuses on natural or treated woods that aim to replicate the aesthetic and technical properties of old-growth teak, still the preferred choice on superyachts.Any talk about teak is inextricably mixed up with the environmental, political and humanitarian situation in Myanmar. Although not exclusive to the country formerly known as Burma, about half the wild teak left on the planet grows in Myanmar, which has long been the de facto exporter of the prized hardwood. However, since June 2021 when the state-owned Myanmar Timber Enterprise (MTE) was sanctioned by the EU, any imports of teak from the country constitute a breach of those sanctions.

Last year the District Court of Amsterdam confirmed the criminal convictions of one company and two individuals for importing teak from Myanmar into the Netherlands via the Czech Republic in breach of due diligence provisions defined in the EU Timber Regulation (EUTR). No one is going to prison and the fines imposed represent little more than a slap on the wrist, but these first prosecutions represent a step towards keeping illicit teak out of the EU and came as a wake-up call for timber merchants and yacht builders alike.

Shipyards are not legally responsible for the sourcing of the teak used on their yachts unless they are directly importing the wood themselves. It usually passes through many hands and only the first importers are required to prove it is legally sourced. But traceability and due diligence can be very difficult to establish, which is why some yards use independent verification providers like Double Helix Tracking Tecnologies, a Singapore-based company that relies on a DNA-based system to verify where the teak originated.

In the past yacht builders have tended to turn a blind eye, but they are well aware of what is at stake. Most have stockpiled supplies of old Myanmar teak, but these are rapidly running out. One decking specialist told us that the top north European shipyards have sufficient supplies for up to eight more new-build projects, depending on size. Understandably, the price of old-growth teak has gone through the roof. Another decking contractor we talked to was recently quoted €50,000 per cubic metre for a batch of stockpiled Myanmar teak, three times the going rate for plantation teak (including wastage, at least 10 cubic metres of teak are required to deck a 70-metre motoryacht). Why Teak?

There are good reasons why teak has been used by boat builders for at least 2,000 years. It has a high oil content, high tensile strength and an exceedingly tight grain, which make it tremendously weatherproof. It is resistant to rot, cracking, fungi and mildew with a low shrinkage ratio, so fluctuations in moisture content do little to change the size or shape of the battens. It also contains silica, which is what lends the wood its non-slip qualities – and blunts cutting tools.

Plantation teak is ready to harvest after 20-25 years, but shipyards much prefer teak that grows slowly in the wild and may be four times older. Young teak trees in the forest have to compete with established trees, so only the strongest grow to maturity. Because of the dense forest canopy they reach for the sunlight without sprouting low branches, resulting in a straight grain with no knots or ‘moisture traps’ that weakens the lumber. Widely spaced plantation trees cultivated in direct sun do grow lower branches, which are pruned off but leave pin knots and moisture traps. Grown quickly to maximise return on investment, they have wider growth rings and a looser grain, which means the wood is less dense.

Janka Wood Hardness Scale

The Janka Wood Hardness Scale measures the force needed to embed a 11.28 millimetre steel ball into a piece of wood. That force is recorded in pounds-force (lbf) in the US, or kilograms-force (kgf) or newtons (N) in other parts of the world. Teak appears on this scale with a rating of 4,740 N, Cumaru is 14,800 N, and Ipé is 15,620 N.

But hardness is not the only consideration for boat builders, nor the most important. Teak is very dimensionally stable, an important factor when laying decks. Its shrinkage coefficient is 5.3% (Ipé is 7.2% and Cumaru is 7.7%). Heat-treated woods are favoured because although they lose a small amount of density, their dimensional stability is improved substantially.

Other factors are Modulus of Rupture (MOR), sometimes referred to as ‘bending strength’, which is used to determine a wood’s overall strength, and Modulus Elasticity (MOE) that measures a wood’s deflection but not its ultimate strength (some species of wood will bow under stress, but not easily break).Into the wild

German decking specialists Wolz Nautic has been using FSC-certified plantation teak for series yacht production for over a decade, processing up to 100 cubic metres of timber per year with results that are “absolutely comparable with previous Myanmar quality… However, the quality of plantation teak depends on the plantation, slow growth and care of the trees.”

“We’ve carried out tests with renowned wood institutes which prove that the plantation teak tested from Latin America shows almost the same performance, properties and durability as, for example, teak from Myanmar – the difference is very small,” says managing partner Michael Wolz.

Laminated teak (sometimes and misleadingly called ‘green teak’) is plantation wood glued together in 1.2mm layers. The lamination process improves durability and also lends the deck a tighter ‘grain’ that simulates old-growth teak, but the seams are susceptible to weathering and the strongest adhesives are far from eco-friendly.

“We began looking into alternatives to Myanmar teak more than 10 years ago and there’s some really good plantation teak out there,” agrees Richard Strauss, CEO of Florida-based Teakdecking Systems that has a base in Barcelona and has installed teak decks on superyachts such as Oceanco’s 109-metre Seven Seas and 127-metre Koru. “Let’s not forget that teak is grown in many places around the world – Costa Rica, Thailand, India, Tanzania, Bolivia. We have four people in our acquisitions team and they travel the globe to ensure not only the quality, but also legality of the teak we buy.”

But performance is not the only consideration. The tight grain of old-growth teak is widely considered more aesthetically pleasing. Although good planation teak may be comparable to Myanmar teak from a technical standpoint, “Visually, some compromises may have to be accepted,” admits Wolz. This is especially true when it comes to superyachts, where the tendency has been to seek out the finest – and often rarest – materials.

In 2008, Lürssen launched a research project in collaboration with the University of Göttingen to investigate different treatments that improve the properties of wood species and make them more teak-like. The result is Tesumo, a treated Limba wood grown in tropical West Africa that its creators claim offers the strength, beauty and warmth associated with teak, and more. “We had already tested alternative natural decking materials, but the results were disappointing because all the other timber species failed in one way or another”, says Dr Bernhard Urban, Head of Development & Innovation at Lürssen. “So we focused on thermal modification and impregnation. Each of these processes led to specific improvements of the tested timber, but neither met our defined requirements for high-quality yacht decking. Finally, we started to test a combination of the two-stage modification processes that led to the desired results.”

Lürssen has been working with Wolz Nautic on Tesumo. Using weight- and noise-reducing cork as a levelling material, the system has been tested on smaller yachts for more than six years with positive results. Custom projects include REV Ocean, set to become the largest explorer yacht in the world. Tesumo was also chosen for 26-metre Project Ocean, the all-aluminium explorer yacht approaching completion at UK-based Arksen.

“As teak is still the expected finish on a yacht, we wanted to find an option with the same look, feel and performance as teak without the same sustainability issues,” says Ewan Hind, COO at Arksen. “While there are some synthetic options for decking, our requirement to find a timber deck with similar properties to teak and an improved end-of-life strategy meant we had a small pool of options. From reviewing the alternative timber options against a range of points, including aesthetics, price point and ease of installation, Tesumo came out as the top choice for our application.”The European Timber Regulation

The European Timber Regulation (EUTR) came into force in 2013 to make it much harder for illegally harvested wood to be sold in the EU. The regulation required operators to exercise ‘due diligence' with verified documentation, although the provisions were often side-stepped. In the wake of the 2021 military coup in Mynamar, several nations – including the US, Canada, Australia, the UK, as well as the EU – imposed economic sanctions that also targeted the Myanmar Timber Enterprise (MTE). Nonetheless, a subsequent report by the London-based Environmental Investigation Agency (EIA) documented how Myanmar teak was still being trafficked through Italy to the rest of Europe. In March 2023, the Forest Stewardship Council (FSC) launched an initiative to focus attention on the ongoing impact of the yachting industry on the world’s forests, and last May the EIA named 12 American timber firms that have imported teak from Myanmar since the start of the 2021 military coup, including several yacht decking companies.

Capable maple

Marine Maple is a treated wood that has been thermally modified, an age-old process that dates back to the Vikings who cured the wood for their ships with fire. Only heat and steam are used to trigger physical and chemical reactions in the wood at a cellular level. In addition to improved dimensional stability, thermal modification adds other desirable properties such as better resistance to mildew and mould.

“Our entire business is based on teak, but we could see the writing on the wall and first started experimenting with alternatives about 15 years ago,” says Jon Winstanley, Managing Director of Modesty Yacht Carpentry in Palma de Mallorca and creator of Marine Maple. “At the very least we had to be able to offer our customers an alternative.”

Winstanley originally focused on thermally modified ash with good results, until the Emerald Ash Borer beetle destroyed tens of millions of ash trees in 30 states across the US. He then switched his attention to hard maple, which is grown in sustainably managed North American forests. Its key features are its strength (harder than teak on the Janka scale – see sidebar), colour and grain straightness, as well as good adhesion qualities to glues and caulking compounds. Heat-treated wood tends to be more brittle and requires care when cutting and bending, but once in place behaves in the same way as teak and requires similar care.

First installed on the swim platform of a busy charter boat in Ibiza and having proved a durable substitute for teak, at the time of writing a Marine Maple deck was being installed on a 35-metre new-build motoryacht. Southern Wind Shipyard is also offering Marine Maple as a decking option on its new 100-foot line of ‘Smart Custom’ sailing yachts.

“Among the options available in the market, we have identified Canadian maple as the most interesting choice for our yachts and their intended use,” says Andrea Micheli, CCO at Southern Wind, which recently completed the first Life Cycle Assessment of a SW105 calculated over a 30-year period. “At least for the time being, we prefer maple over cork, reconstructed teak, reconstructed wood, and other synthetic materials, due to its better aesthetic and overall technical characteristics.”

Oceanco commissioned an independent study of Marine Maple, along with other treated wood alternatives, to compare its properties to teak. The principle tests measured the uptake of salt water and the effect on the equilibrium moisture content (EMC), dimensional stability, and cleavage strength as a measure of the tendency to splinter. Marine Maple did not perform quite so well as teak in its reaction to the salt water treatment, but has a cleavage strength that is superior to teak. Tough is not enough

You would think that other hardwood species could easily stand in for teak, but it’s not that simple. Cumaru, for example, sometimes called ‘Brazilian teak’, is among the hardest and most durable woods on the planet. Ipé is another tough South American variety known as ‘ironwood’ that has the same fire rating as concrete or steel. Ipé is so dense it sinks in water, which could be problematic on a yacht but also makes working it very difficult. The issue with both these species, however, is that illegal logging and clear-cutting (the logging method in which resilient natural forests are harvested and replaced with man-made tree plantations) have a high ecological impact.

Iroko or ‘Africa teak’ is a very durable wood that silvers over time like teak and is much less expensive. According to the IUCN Red List, a database of the conservation status of the world’s biodiversity, Iroko is classified as ‘Lower Risk’, a classification below ‘Vulnerable’. But that assessment was made in 1998 and documenting the journey of the lumber with a chain-of-custody paper trail to prove the wood was legally sourced from a certified rainforest in West Africa is not straightforward.

Meranti or shorea wood is a tropical hardwood from Southeast Asia that has many of the same properties as teak. Unlike tropical hardwoods that have become endangered due to illegal harvesting, the bulk of Meranti wood is supposedly sourced from sustainably managed forests. Nonetheless, it is listed as endangered on the IUCN’s Red List due to excessive logging, habitat loss, insufficient regeneration and a slow recovery rate.

Accoya is the brand name for a sustainably sourced soft wood produced in The Netherlands with a low total lifetime carbon cost that has undergone a non-toxic modification process using acetic acid. This basically amounts to pickling the wood in really strong vinegar that interacts with the molecules to make them resistant to binding with water. The result is real wood that doesn’t rot, warp, swell or shrink.

Cork is a bark rather than a wood that is harvested without harming the tree. It is naturally water-, rot- and stain-proof, pleasant to walk on, doesn’t heat up underfoot, acts as an acoustic and thermal insulator, and requires minimal maintenance. Combined with manufacturing processes to increase its consistency, MarineCork is marketed by Italy-based SACE Components as “the ideal solution for those looking for quality alternatives to teak and imitation teak.” MarineCork has been adopted by Azimut Yachts for its new Sea Deck range and during Milan Design Week 2023 the builder displayed a floating installation made from recycled cork. Arksen is also offering cork as a decking option.

Hot stuff

Feadship is also actively looking into natural, treated and composite alternatives to teak. Its research ranges from simply exposing test panels to the elements on the roof of the shipyard (with periodic cleaning as per manufacturer protocols) to more specific analyses to measure hardness, water absorption, shrinkage and elasticity. One test measures thermal effusivity, the ability of a material to exchange heat with its immediate surroundings (ie. our bare feet), which translates into how cool or warm a material ‘feels.’ Surprisingly, natural teak has quite high effusivity and feels hotter underfoot in relation to some composite alternatives like Flexiteek or Esthec.

“An unforessen difficulty we came up against was getting hold of product samples to test,” says Giedo Loeff, Head of R&D at Feadship. “This was due to reasons such as limited supply and ongoing development, or because the product was simply no longer available.”

One such product to have fallen by the wayside is Lignia. Its manufacturers claimed the resin-infused softwood made from FSC-certified pine had aesthetic and tactile properties very similar to teak, and was even longer lasting. Spirit Yachts in the UK decked its 50CR sailing yacht with it, yet despite winning a DAME award in 2019 Lignia went into administration two years later. Tipping point

Wild forest teak is not necessarily gone forever. Myanmar Timber Enterprise continues to harvest and stockpile teak and if democratic government should return to the country, or the military junta improve its human rights record and forestry practices, sanctions could be lifted and a ready supply of old-growth teak come back online.

But that possibility overlooks the ethical and environmental arguments. Wild teak may be desirable, but cutting down century-old wild trees to make decks that might last 20 years is clearly irresponsible from an environmental perspective. Once felled, the wastage is mind-boggling and the yield for decking purposes from a good teak log may be as little as 12 percent. Moreover, because the logs are first quarter sawn and then cut across the growth rings, which is what lends teak deck battens their straight grain and structural stability, fewer boards can be made from each log.

Our obsession with old-growth teak looks increasingly anachronistic when feasible and sustainable wood alternatives are available. They may not have exactly the same technical or aesthetic properties as Mynamar teak, but not using them is hard to justify in an industry aiming to improve its green credentials.

But the biggest barrier to more widespread adoption of alternatives to teak is likely ongoing reticence among the owners themselves: “It’s always hard to break traditions, but we bring it up for discussion every single time,” says Lürssen’s Dr Urban. “Clients are aware of the sustainability issues, but not all are really willing to be a guinea pig.”

This article was originally published in Issue 3 of How To Build It, you can download the magazine for free here.