The Story of the ÖK Hull

Having owned several boats and yachts himself, Össur Kristinsson, the inventor of the ÖK Hull, has had a passion for boats that dates back to his childhood when he built himself a canoe at the age of 15. Then some twenty five years ago while living in Stockholm, Sweden, Össur was inspired by the work of engineer Fredrik Ljungström to create a new hull concept based on Ljungström’s arc-of-circle radius, invented for his circular arc hull. As boat hulls are typically hidden out of sight, this remained one of Ljungström’s lesser known ideas.

Having begun research and development for the ÖK Hull in 2005, 2011 became one of the most important years of development when Rafnar began a research and development collaboration for tactical boats based on the ÖK Hull with the Icelandic Coast Guard (ICG) and the Icelandic Association of Search and Rescue (ICESAR). As ICG and ICESAR are among the most demanding end-users of tactical vessels in the North Atlantic, this collaboration effort proved to be invaluable and has since then given Rafnar and the ÖK Hull technology international endorsement and appeal. A common saying among ÖK Hull fans is, “if the ÖK Hull works for the ICG and ICESAR, it'll work for us”.

The Unique ÖK Hull

What it is and how it works

The ÖK Hull is a revolutionary hull-and-keel technology that will ultimately disrupt marine industries globally. Confirmed by independent research to be capable of up to 20x less slamming than competing hulls, the ÖK Hull ensures otherwise unattainable seakeeping in the most extreme marine environments. A product of the harshest conditions of the North Atlantic, the ÖK Hull has been confirmed by professionals worldwide to provide mariners with endurance and comfort in crafts that are practically impossible to make unsafe. This is achieved without compromising cruising or top speeds, while providing owners with the benefit of lower vessel life cycle cost not only from mechanical and on-board equipment fatigue, but also from medical, disability and insurance related costs. The ÖK Hull offers a uniquely smooth experience.

When accelerating, the ÖK Hull raises itself horizontally and maintains planing. The pivot point remains in the hull's center instead of in the stern, which is not forced downwards during acceleration. The keel shape keeps the vessel steady in the water, allowing for unrivaled speed and grip in turns. The ÖK Hull always remains steady and fixed in the water and almost never slams on waves. Due to the ÖK Hull's shape, no wake is created behind the vessel.  The ÖK Hull's top speed is only limited to engine output produced. 

Benefits of the ÖK Hull

Up to 20x reduction in slamming verus deep-v planing hulls

Exceptionally smooth and comfortable due to limited slam on waves.

Significantly reduced slamming results in less mechanical and equipment fatigue, extending the lifetime of expensive electronic equipment on board. 

Greater on-board safety from significantly reduced slamming means reduced risk of injury, lower crew & passenger fatigue and related costs

Precision performance without compromising cruising or top speed.

Immediate handling response with no sliding

No wake created behind vessel, resulting in less water disturbance

Exceptional stability and balance when idle and at speed

High payload capacity without compromising cruising or top speed

Built for work, the ÖK Hull procides expetional control over one's perimeter and zone of responsibility.

Built for leisure, the ÖK Hull is the means to an enduring lifestyle of comfort and exploration.

Science of the ÖK Hull

Trial conducted by the University of Iceland

The ÖK Hull significantly increases on-board safety for crew and passengers. Independent research conducted by the University of Iceland compared the ÖK Hull to other hull forms in vessels of equal size and weight. The study demonstrated that Whole Body Vibration (WBV), which can negatively impact the crew’s health, are significantly reduced in Rafnar’s boats. The research involved studying the hulls‘ behavior in various conditions, including different directional angles when hitting waves, different wave heights, cruising speeds and wind conditions. The study focused on WBV standards defined in ISO 2631-1:1997. Simply put, a health guidence caution zone is defined as being above 0.57 g, where impacts above this value are considered to be hazardous. When measuring instances of hazardous conditions at the bow of each craft, the ÖK Hull only showed only six instances compared to 112 in the comparison craft. Likewise, instances measured in the cockpit of the ÖK Hull were only six compared to 33 instances of the comparison craft.

While the study is still underway, with more comparison vessels being studied to improve accuracy, the results so far clearly indicate that the ÖK Hull demonstrates substantially superior stability and comfort to comparison crafts. The results show that the ÖK Hull is capable of significantly reducing the risk of prolonged exposure to whole body vibrations, greatly improving on-board safety for crew and passengers and extending the life time of expensive equipment and the vessel itself.

The study, conducted by the Engineering Research Institute of the University of Iceland,is available here.

The inventor

Össur Kristinsson

Össur Kristinsson founded Rafnar in 2005 in order to work on and develop his unique hull design ideas and thinking. In the past, he has been a founder and shareholder of several companies with challenging and disruptive ideas. 

A Prosthetist and Orthotist by education, Össur Kristinsson founded Össur hf. in 1971. Össur hf. (OSSR.DK) is now a world leader in prosthetics and orhotics, with an annual turnover of approximately USD 500m annually. 

Össur Kristinsson was the main shareholder in Hafmynd ehf., now Teledyne-Gavia ehf., a company designing, manufacturing and selling Autonomous Underwater Vehicles (AUVs).