Reclaimed timber should be the preferred wood of choice for repairing the deck, knees, hull, and mast of old boats. It is not typically the primary material for entire boat construction, which is normally new timber, and testing may be required for structural timbers. Reuse is more common in specific applications where unique properties and environmental benefits can be leveraged effectively. Here, we discuss reclaimed timber, natural new wood, chemically impregnated wood and synthetic wood, timber or lumber.

Reclaimed or salvaged timbers

Reclaimed greenheart and purpleheart are exceptional timbers, used extensively in marine structures such as piers and groynes, and will make strong, durable boat decks. England's best-known supplier is Salvo member Ashwell Reclaimed Timbers in Essex, whose heritage is wooden shipbreaking. Reclaimed greenheart is often used for decking, cladding, and other marine applications where strength and durability are crucial.

This year, reclaimed opepe was used in major repairs to Raybel, a 100 year old Thames barge lying at Sittingbourne. Opepe is a tough tropical hardwood with an even interlocked grain, but it was not chosen for its characteristics but because it was available in the large sections and lengths needed for the repairs.

Reusing reclaimed timber is more eco-friendly than using new timber because it reduces demand for newly sourced lumber, helps curb deforestation, stores sequestered carbon and eliminates pollution caused by burning or methane emitted by decomposition in landfills. Reclaimed wood, especially hardwoods like Greenheart, can be very durable and long-lasting. The aged appearance can add character and a unique aesthetic to boat projects.

The quality and consistency of reclaimed wood can vary significantly. Careful selection and grading are necessary to ensure the wood is suitable for marine use. Resistance testing may be needed to ensure the centres of hardwood beams are sound - see Resistograph by Rinntech.

Treatment considerations: Some reclaimed wood may have been treated with chemicals that are not ideal for boat construction. For example, tanalized pressure-treated wood is generally not recommended for boatbuilding because copper chrome arsenate is toxic to fish. Structural limitations: While reclaimed wood can be used for certain parts, it may not always be suitable for critical structural components of a boat (see Raybel's opepe above). Additional processing: Reclaimed wood often requires cleaning, denailing, resawing, and careful preparation before it can be used in boatbuilding.

Cost and availability: While potentially more eco-friendly, reclaimed wood suitable for boatbuilding may not always be readily available or cost-effective compared to new marine-grade timber. (Try a want ad on SalvoNEWS - one of our first was an ad in 1991 by SS Great Britain for jarrah to be laid on the ship's weatherdeck.)

Although reclaimed wood can be used in certain aspects of boatbuilding and repair, it is not typically the primary material for entire boat construction. Its use is more common in specific applications where its unique properties and environmental benefits can be effectively leveraged.

New natural wood

Teak and its challenges

The 2021 military coup in Myanmar has significantly impacted the boatbuilding industry, leading to a ban on importing high-quality teak from the region. Plantation teak from countries like Brazil, Java, and various parts of Central America is now being used, though it often lacks the size and grain quality of Myanmar teak. Suppliers are encouraging boatbuilders to adapt by using shorter and narrower boards, which are more readily available and cost-effective, and then computer-mapping the shapes to conceal butt joints underneath deck fittings. Teak does not last forever. Modern teak decks can lose 1mm of thickness per year through scrubbing. Unfortunately, a ban on importing illegally logged timber into the EU hasn't stopped the trade, states Yachting World, evidenced by court cases in Denmark, Sweden, Germany and Holland following the discovery of illegally imported teak, which recommends using salvaged teak provided it is from a known source. On deck, the most popular shade is freshly scrubbed teak, but the most sustainable shade is silvered, weathered teak. The forests of Myanmar have long been exploited for their monetary value, benefiting military and economic elites. The entire legal state forestry and timber trade sectors are riddled with corruption. Current laws often criminalise local people while failing to implement effective centralised management. Myanmar's government falsely presents the teak trade as legal and sustainable. A two-year undercover investigation by the Environmental Investigation Agency (EIA) revealed a system of fraudulent trade that runs parallel to the official legal trade involving senior military and government officials.

West African and North American hardwoods

West African countries are now exporting timber only after machining, which increases its value but poses challenges for boatbuilders needing larger, unprocessed logs. Species like khaya, sapele, and iroko are affected. EIA has raised questions about the legality of sapele logging in Ghana and Cameroon.

In North America, new regulations in British Columbia have restricted the felling of trees older than 250 years, impacting the availability of high-quality softwoods like Sitka spruce, western red cedar, and Douglas fir. This has led to higher prices and reduced quality of clear timber. Clear timber is a result of the canopy shading out lower branches, which die and fall off, allowing the tree to grow without knots.

Larch and oak

Sanctions against Russia have made Siberian larch, prized for boatbuilding, unavailable. In the UK, slow-grown northerlyScottish larch is considered the best alternative. Oak remains available for straight lengths, but oak knees are less common due to misconceptions among landowners about market demand.

Synthetic timber deck and chemical issues

With teak becoming scarcer for decks, alternatives on the market include synthetic options made of composite PVC and polyethylene made to mimic the appearance and properties of real teak, pines impregnated with phenolic formaldehyde resins and heat-treated maple. However, these alternatives have faced issues like splitting and cracking, prompting some boatbuilders to revert to traditional timbers like douglas fir. One of the best-known brands, Flexiteek, has been producing PVC decking for 25 years, with demand growing at 20% and production in 2020 at 80,000m2. An advantage of Esthec is that it comes in single sheets, which reduces deck leakage. Fungus and mould inhibitors are added to synthetic decking.

The chemicals used in synthetic decking's fungus and mould inhibitors typically include:

Biocides: These are antimicrobial agents that prevent the growth of mould, mildew, and fungi. Common biocides include quaternary ammonium compounds, isothiazolinones, and chlorothalonil. QACs and copper-based preservatives are particularly hazardous due to their acute and chronic toxicity to various aquatic organisms. QACs and azalea fungicides are also highly persistent in the environment, leading to long-term ecological impacts.

Fungicides: These are specific types of biocides that target fungal organisms. Examples include copper-based compounds, zinc-based compounds, and organic fungicides like propiconazole and tebuconazole.

Algaecides: These chemicals prevent the growth of algae, which can also contribute to mould and mildew issues. Common algaecides include copper sulfate and benzalkonium chloride.

Chemicals are often incorporated into wood treatments to provide long-lasting protection against fungal and mould growth, especially in environments where the wood is exposed to moisture and humidity. They can be hazardous to both human health and the environment. They can leach into surrounding waters and soil, posing risks to aquatic life and ecosystems. Many chemical preservatives persist in the environment, meaning they do not break down easily and can accumulate over time, leading to long-term ecological impacts.

Preservative treatment

Traditional methods include coating the wood with a mixture of linseed oil and paraffin or kerosene. This treatment helps to repel water and prevent rot and mildew. Clear wood preservatives are often used to protect against fungal decay and insect infestation. These preservatives typically contain biocides and fungicides that penetrate the wood and provide long-lasting protection. Chemicals such as copper-based preservatives (e.g., alkaline copper quaternary, or ACQ) are used to treat wood, making it more resistant to decay and insect attack. These treatments are particularly effective but can be hazardous to the environment and aquatic life. Boiled linseed oil is commonly used in Scandinavia to treat mahogany and other hardwoods. It helps to keep the wood stable by replacing water with oil, which does not dry out easily. Synthetic treatments and coatings of epoxy resins are designed to penetrate deeply and provide a robust barrier against moisture and decay.

Sources
Classic Boat April 2024
https://www.yachtingworld.com/features/teak-alternatives-decking-options-126023 2020
https://eia-international.org/news/corruption-oiling-myanmars-criminal-teak-trade-reaches-heart-government/
https://forums.ybw.com/threads/using-tanilised-wood-for-wooden-boat-building.391175/
https://www.smallboatschool.com/blog/good-boatbuilding-wood-and-how-to-find-it
https://ashwelltimber.com