We are a small, highly specialized custom fin manufacturer. We like to offer competition and enthusiastic, recreational surfer the best products made of the best materials available on the market with the quality and structural requirements that are comparable to aerospace standards. Our products are real custom fins where nearly everything can be adopted to the customer needs.

Our products are not “created” by trial and error. We have more than 30 years experience in research and development of different products in different industries. This background allows us to define and follow a product development process with clear phases and gates.

Systematic testing in laboratory (parametric and endurance) are the first step to verify the results out of simulation (fluid dynamics) and calculations (lay-up, bending/torsion stiffness, point of breakage, etc.) done in advance. Correlation of these test results with test results from our test riders on the water is closing the loop.

Our laboratory test bench is state of the art, completely computerized, pneumatically actuated and is able to measure all mechanical parameter influencing the fin’s performance. Every fin that is delivered to our customer is tested before on that bench for different structural stiffness measurements and overload tests to guarantee the specified stiffness and durability of that fin.

The fins are made of aerospace-carbon (uni-directional and bi-diagonal) in CNC-milled molds under high pressure and temperature control. We have our own mold shop including a high speed CNC-mill.

Sonntag-Fins started design and development of windsurfing fins around ten years ago. The experience in designing and producing fins is going back into the 80s when the first models were produced in glass and carbon composite.

But new materials, new research results, new machinery (CNC) and most important the usage of computer to simulate, calculate and design were the reason to come back to market.

Each fin is adapted to the customer needs. Bending stiffness, torsion stiffness and its distribution over length and the rake can be adjusted to the requirements of our customers.

The models in production and development are covering the racing disciplines Speed and Slalom. But also good freeriders will find a fin fitting perfect to their requirements.