+ simple
+ performante
+ user friendly

Inflated Wing Sails (IWS)

IWS is stable in every wind conditions. There is no pressure on the boat‘s structure. IWS offers a smooth balanced new way of sailing. No more winches, halyards, shrouds or complex deck equipments.
«it is the first sailboat that really gave me pleasure sailing because it mixes aircraft and yachting technologies…»

Laurent de Kalbermatten, aviator and IWS creator

«IWS offers a sensation of freedom with a balanced rigging while minimizing effort on the boat»

Edouard Kessi, sailor and IWS creator

A concept

based on paragliders and on inflatable aircrafts

IWS is made of:
  • A double skin forming a symetrical airfoil
  • Fans placed inside the leading edge, stabilizing the sail’s shape for every wind conditions
  • Free-standing and retractable mast located at the airfoil’s aerodynamic center

The IWS for yachts:

a soft and groundbreaking wing

The advantages

of IWS:

  • The sail flies vertically
  • The NACA airfoil has been studied to develop a high driving force for a low righting moment
  • Using a symetric airfoil allows to tack from one side to another without having to trim the sail shape
  • The symetric airfoil is balanced and place itself in the best position to maximise the driving force
  • The aerodynamic center stays stable in every wind condition
  • This kind of sail could easily be driven by an automatic system


reduces effort on the boat:

  • Shape control using the internal pressure
  • no battens
  • no local stress
  • better aging
  • The wing flies vertically and does not create local stress inside the membrane (light sail cloth used for both ribs and the fairing)
  • Little heel angle upwind
  • Perfect for gigantic sails such as superyachts
  • Free-standing, retractable and light mast hidden inside the wing
  • Less leeway control needed, lighter keel and boat reinforcements
  • A refined deck free of any hardware

IWS behaves like a muscle,

stabilized by high internal pressure

  • No flapping
  • No dynamic stress
  • Spectacular absorption of the pitching effect
  • Wing twist controlled by internal pressure

IWS sailplan

is balanced around the mast:

  • No compression forces in the rigging which allows the use of a retractable mast
  • No leech tension. The sheet is only used to adjust the wing in its best  angle
  • The free-standing rigging allows gybing with the wing going forward around the mast, which makes the manœuvre a lot easier

IWS controls the sail area

by mast height:

  • Mast and sail expension varies according to the desired sail area
  • Dropping the IWS is made by deflating the wing and retracting the mast
  • The light boom, called “Nest”®, is integrated inside the wing base and receives the part of the sail that has been dropped and deflated
  • Being able to retract the mast allows a huge decrease in drag and pitch forces during motoring or while at the dock


is ideal for:

  • Cruising Yachts purified from deck hardware and easier to sail.This type of rigging offers a brand new yachting philosophy
  • Huge sails for passenger or cargo ships. With IWS, there is no more stress inside the sail cloth, the rig or the ship structure. This system would allow sail propulsion for this kind of vessel


the history


  • prototype created using a Laser dinghy.


  • International patent application.
  • Comparison between a normal Laser dinghy and one with the IWS system.
  • Performances and advantages validated.


2017 news:

  • To analyse all the advantages of the IWS system, a 42m² wing has been built for a 5,5m one design boat. The retractable mast made out of 5 sections deploys up to 13m using a pneumatic system
  • Test period is finished. The boat sails on lake Geneva and is at your disposal for sea trials
  • Our experience aquired on the IWS proved that this system is very simple, efficient and user friendly