EXOSKIN
OUR METHOD OF BUILDING YACHTS WITH WOOD
Used for centuries in boat building, we design yachts in wood again for many of its properties which are still to be discovered with modern design methods.
The method we offer is one of the most advanced wood construction today and all details add up to a 20% increase in strength to weight ratio. It allows us to build boats of all sizes, which are stiff, lightweight, and contribute to the reduction of CO2 emissions.
For the build of our 15 meter design Elida, we decided to continue the development of modern wood boat building techniques, as we saw an opportunity to use the latest developments in the selection of wood, material testing, progress in adhesive properties and computer optimization methods in order to bring this material to modern standards.
The construction method is now certified by DNVGL including for the toughest sailing conditions of offshore racing and was used successfully in the 2023 Rolex Fastnet race.
As time moves on and we all re-discover the possibilities of this natural material and the drawbacks of carbon fiber outside of pure racing, we think it deserves a serious look for your next project.
Discover more about this exciting new method below.
WHEN PRECISION MEETS NATURE
4 LAYERS OF WOOD, AND AN OPTIMIZED COMPOSITE EXOSKIN
The Exoskin construction process
The construction process we have developed has little to do with classic yacht building and more to do with high-end composite manufacturing.
The main shell of the hull is made of 4 layers of wood glued together with our specific epoxy based structural adhesive.
The layers of wood are placed at a specific angle to the hull, and in thin layers of varying thickness to allow them to follow the curvature of the hull shape with minimum bending. It is a method which takes time, as each layer must be put in place in our mold, glued with modern vacuum bagging methods for even pressure, before moving onto the next layer, step by step. It is a wonderful process.
Once all layers of wood are glued together, the hull is faired by sanding thus saving the otherwise extra weight of fairing paste. Finally an outer layer of carbon seals the wood from humidity on the outside and for improved resistance against impact and sealed on the inside and along all edges before the structure is assembled.
To bring the wood construction to modern standards of stiffness and strength, the Exoskin itself is laminated comprising of global carbon fibre and Eglass reinforcements optimized using topological optimization methods, a technology borrowed from Formula 1 and the America’s Cup.
The result is hull which requires no maintenance and is both lightweight and robust.
‘It is a method which takes time, as each layer must be put in place in our mold, glued with modern vacuum methods for even pressure, before moving onto the next layer. It is a wonderful process’
SUPERIOR MATERIALS
CREATE SUPERIOR SENSATIONS
THE WOOD CORE
While wood has always been used for boat building, it inhibits an inherent weakness in the variation of its properties which to us had to be removed.
Wood selection has been improving in the past decades and working with our wood mills and certification companies, we have now defined a selection process which allows to reduce the variability of the wood we use. This has resulted in a 20% gain in material properties for the same weight.
To remove the variation of properties, we select wood which are within an exact band of density so that the behavior can be precisely calculated and certified. It is more work upfront, but results in a better product for you and no wastage.
It has meant creating direct links with local agents of wood mills who are able to go on site, take specific measurements and refuse wood which do not comply with our specifications. The rest of wood is used by other companies instead of being shipped to us and discarded.
Among many species of wood, we have selected Northern Spruce as our wood of choice: a type of pine which grows primarily in northern Europe and Alaska. A light wood makes for a thick hull which benefits from additional local stiffness. Too light however and it may become too brittle and the strength of spruce is just what we are after and its use, including in modern aviation, means we can find the quality we are after in large volumes.
‘working with our wood mills and certification companies, we have now defined a selection process which allows to reduce the variability of the wood we use’
Material testing at Airbus facility
Picture taken durign the build of our 15 meter design Elida
OUR SPECIFIC WOOD ADHESIVE
You may be familiar with the term wood epoxy construction which was developed in the 1980s. While the technology has allowed to totally remove the arduous maintenance of classic wood construction it has not benefitted from the full advancement in science of the past 40 years.
After conducting testing at an Airbus facility we realized that not only the wood was much stronger than initially thought but that the resin that glues the layers together was the heaviest part and least loaded. As wood is much stiffer than resin, it carries most of the load.
Conducting systematic testing of our own resin mix has allowed us to define our own recipe for an adhesive which is just a little stronger than the wood itself, and much lighter. A recipe we keep close to our chest.
‘the adhesive is a key ingredient of the construction, it allows the load to be shared between each layer of wood, and we ensure it has just the right strength’
WOOD CONSTRUCTION AND THE ENVIRONMENT
ECOLOGICAL PERFORMANCE DELIVERED
As the world grows conscious of how the environment impacts our wellbeing and comfort, wood is one of the materials to consider for your yacht construction.
CO2 is naturally present in organic materials from which petrol is made of and pre-dates the current climate era. With today’s composite materials, petrol is extracted from the ground and CO2 is released in the atmosphere when transformed into plastics, resin, fibers and all other by-products. Reducing the amount of additional CO2 in the air is now an objective across all main continents.
By storing CO2 instead of releasing it in the air, growing trees and storing CO2 in everyday objects has a net effect in the reduction of emissions which far outweighs the CO2 emitted during its transport and transformation. This, combined with using less carbon fiber in the construction of our yachts has a real quantifiable effect.
Third party analysis has shown that our method reduces CO2 emissions during the construction by 21% compared to a full carbon fiber construction and we hope to keep improving on this result in the near future. International targets are currently for a reduction of 45% by the year 2030 and choosing the Exoskin construction method is a step towards achivieving this goal.
Key facts:
– 21% lower CO2 emissions compared with a full carbon fibre construction
– 54% lower CO2 emission for the hull construction
– Bare hull weight 620kg in Exoskin vs 510 kg for a carbon and vs 570kg for Eglass
– Certified by DNVGL for offshore racing Category A
From yacht construction to modern architecture, wood is quickly gaining traction. On top of the performance of the material, wood naturally benefits from other advantages: the local softness which dampens the sound, and the air inside which provides superior thermal insulation.
A noble material and a timeless charm. It deserves your attention for your next project!
