About Reefing Rotor Sails

The History

Carbon-based fuel was cheap and widely available in the 20th century and Flettner’s rotor sail idea did not achieve any lasting commercial success.

Carbon-based fuel is now greatly more expensive and blamed for excessive greenhouse gas (GHG) emissions. The world’s 50,000 plus shipping fleet moves 90% of the world’s commerce, but produces more GHG’s than all airlines combined. Suddenly, the world needs Flettner’s invention to significantly reduce GHG emissions.

About Rotor Sails

Rotor Sails in the Modern Era

Unfortunately, the 21st Century version of Flettner’s invention exhibits the same old problem – ROTOR SAILS DON’T REEF!

Some designs allow the rotor sails to tilt over to pass under bridges or overhead wires, but this modification is no help during a storm at sea.

Norsepower Oy Ltd, a Finnish company is the world leader in providing modern rotor sails. Norsepower’s rotor sails don’t reef and cannot function in winds above 70-knots. To compensate for periods of excessive winds, or even the 150-knot winds of a Category 5 hurricane, Norsepower provides an extremely robust product. However, if they could reef these rotor sails, they could reduce the weight of their design by 75%.

Another entry in the rotor sail market, Magnuss, Inc., provides a product called the Vertically Variable Ocean Sailing System (VOSS) which has the ability to lower their rotor sail design into a massive, below deck silo on the ship when necessary. A feature that is particularly handy when tying up to a pier with dockside cranes. However, the VOSS cannot be retro-fit to any existing ships.

The VOSS can only be installed on new construction vessels.

Modern Rotor Sails 2

Magnuss VOSS identified the market demand for a rotor sail that can be lowered (reefed), but their design cannot be employed by over 50,000 major customers who want it. Between Norsepower Oy, Ltd and Magnuss, Inc. a very large market niche has developed.

Enter Reefing Rotor Sails

Reefing Rotor Sails has a patent pending design for a new and improved rotor sail structure which raises and lowers the rotor sail on demand. Our design can be retro-fit on any of over 50,000 merchant vessels and can actually be moved from ship to ship relatively easily. We intend to become the world’s sole provider of reefing rotor sails which can be retro-fit to any of the world’s 50,000 existing merchant vessels.


About Our Founder

Our founder, John Donovan, is a serial entrepreneur who spent his youth on the waters of Long Island Sound, several years as a US Navy Surface Warfare Officer and Main Engines Officer on the USS Iowa (BB-61), is a retired Special Agent of the FBI, as well as a former Open Source Intelligence Analyst. John has a passion for developing the most elegant solution to complex problems. That passion, tempered by a life-time of solving complex and difficult problems, birthed the Reefing Rotor Sail design.