Sep 28 2010
Why not let the mast of a sailboat be part of the sail area, which then becomes larger and increases the speed potential of the boat? Tue Pii Korremann, owner of the company Watercraft Innovation, would like to look into this possibility.
So the mast was to be designed as a wing profile with the sail attached to the trailing edge. In this way the mast and sail work together constantly. At the same time the profile should perform regardless of how the wind hits the sailboat. A symmetric profile was chosen as opposed to a wind turbine blade or aircraft wing, which are asymmetrical with the purpose of obtaining increased lift.
For this innovative mast, Thu Pii Korremann chose fibreglass composite material, a more optimal solution to sailboat masts than aluminum, which most sailboat masts are made of today. For more advanced types of his new boat, Tue Pii Korremann plans to produce masts made of carbon fibre composite material which is a more costly, lighter and stronger material.
One thing is designing an innovative mast, but will it stand the strain when the sailor challenges the boat to the utmost in strong wind, far out at sea? To find out Tue Pii Korremann needed the help of someone to calculate the strength of his mast design.
"I had some ideas regarding the size of the catamaran, technical details and simple handling of the boat. The most important thing for me was to create an entirely new concept of a catamaran, easy to handle both at sea and on land. It would have to be so light that you could easily place its separate parts on top of a car. Therefore, it should also be possible to disassemble and reassemble it easily and quickly. In short, a catamaran with a simple structure and safe to sail in, "says Tue Pii Korremann. In fact, he even designed a mast himself and had it made. "But it broke because it was not strong enough when loaded to the extreme, so my "best guess" was not good enough, I needed more accurate calculation of strength, than I was able to make," says Tue Pii Korremann.
As he knew that Risø both deals with wind turbines and materials research, he contacted Louise Vogel Georgi, business developer at Risø. "Louise was very interested in helping me progress with my project. She told me about the knowledge coupon offered by the Danish Agency for Science, Technology and Innovation to small and medium businesses that not usually work together with knowledge institutions," says Tue Pii Korremann.
Watercraft Innovation develops and markets multi-hull boats, i.e. sailboats with 2 or 3 hulls placed at intervals of a couple of metres and kept together by transverse girders. The first type of catamaran has already been developed and is about to be marketed. It is so easy to handle that a person can put it on top of a car, drive to the beach, put it together in 10-15 minutes and go for a sail at full speed. It is just as easy as go surfing. The hulls are 4 metres long, the mast is 6 metres high, and everything can be separated into parts, each part not weighing more than 20 kilos. This allows a single person to put the catamaran on top of a car as easy as anything. Tue Pii Korremann, owner of Watercraft Innovation, is "the test pilot" himself. In the long term, Watercraft Innovation is going to produce other types of multi-hull boats, too.
The knowledge coupon ("Ny videnkupon") aims to support these companies in buying knowledge or research in connection with research and innovation cooperation among small and medium businesses and knowledge institutions.
Helped by Lars Pilgaard Mikkelsen and Hans Lilholt from the Materials Research Division at Risø DTU, Tue Pii Korremann applied for a knowledge coupon. The application was approved and Tue Pii Korremann received DKK 50,000 which would be spent on paying for the consultancy provided by Risø. Tue Pii Korremann was to add a corresponding amount to the knowledge coupon as his own contribution, which could be in the form of his working hours.
The mast is made of fibreglass composite material put in several layers on top of each other. The fibres of each layer can be arranged parallel or in a somewhat inclined angle compared to the previous layer. The number of layers and the combination of fibre directions are crucial to the strength of the mast.
"With a knowledge coupon worth DKK 50,000 we had to consider how to complete the project and still have enough money. Within this limit, we were only able to check the solutions which Watercraft Innovation had reached. There was not enough money for alternative solutions," says Lars Pilgaard Mikkelsen. Because these kinds of projects must be carried out at commercial prices in order not to create distortion of competition in relation to for example private consulting engineering firms.
Lars Pilgaard Mikkelsen started assessing the strength of the materials to be used for the mast and subsequently calculated the loads on the mast by means of a sophisticated computer model.
Calculations have been made of the mast strength in three typical situations as the sailboat moves across the water at full speed. In the first situation, the sailor is hanging slightly out of one side of the boat to provide balance against the wind pressure on the sail. In the second situation, the sailor is hanging even further out of the boat side on a trapeze, i.e. connected to a line attached near the mast top. This allows the boat to sail even faster. The third situation corresponds to the load you have when things go wrong. The boat might tip and the mast will hit the water at full force.