BOW

With the BOW sail the GUNSAILS R&D team introduces a completely new concept in sail design.
Within 2 years of continuous development, Pieter Bijl and Renato Morlotti have managed to realize this innovative idea in a sail. The BOW offers new dimensions in handling and wind range and shows a unique efficiency. With its adaptive capabilities, the BOW delivers constant power and effortless drive across a huge wind range.
The sail is not only perfect for foiling, but also provides a new feeling of windsurfing on a freerace or slalom board. This innovative concept also includes the specially developed BOW FLEX mast, which is rotating within the sail.

The BOW concept is based on a new sail outline with an extreme bending curve in the top. This extreme curve is only achievable with the BOW FLEX mast.
Due to the low luff tension and the innovative design, the sail does not have any loose leech. In the following the functionality of the BOW concept is explained in further detail.

Thanks to a special friction bearing, which allows the mast to rotate within the boom, the mast can rotate inside the sail, thus allowing the upper area of the sail to twist and bend away.
In contrast to the Loose Leech concept, where only a small part of the leech twists, the BOW has a much larger area to adapt to the strength of the wind.
When the wind strength and thus the wind load in the sail increases (high loading), the upper part of the sail turns leeward and the profile adapts dynamically.
The holding forces on the boom remain the same. Only the profile adapts to the higher loading.
When the wind force and thus the load in the sail decreases (low loading), the sail turns back to its original position. Now, the lower wind energy is compensated by the more efficient profile.
The drive as well as the holding forces remain the same. This ability facilitates handling enormously and also improves performance while going upwind.
The described adjustment of the BOW is more dynamic and effective than the Loose Leech mechanism. Due to the well defined and firm edge at the leech, there is no fluttering and the associated small stalls in the profile.
CONCLUSION
Similar to a Loose Leech sail, the BOW regulates itself in gusts and wind holes, but the available area is larger and more efficient. Thus, it covers a much larger wind range in total.
For the windsurfer, this ability leads to an effortless and comfortable windsurfing experience, combined with the performance and drive of a camber sail.
Due to its continuous drive and feather-light handling, the BOW sail is predestined for foiling.

The ground of any sail design is based on a tension triangle that is created between the clew, top and mast. This is also the area which can be actively controlled by the windsurfer at the boom. The special outline of the BOW sail allows it to have a bigger area within the tension triangle. The now bigger area of the sail that can be directly controlled by the windsurfer, does lead to a significant increase in efficiency and control. A BOW sail can therefore be chosen in a smaller size compared to a Loose Leech sail.

Current sail concepts have the ability to adapt to a certain degree to the prevailing wind force. The area that allows the load to be redirected from the sail is called the release area. Marked in blue here. The adaptation of the BOW sail, caused by the rotating
and very flexible mast, enlarges the release area considerably and lets it extend far into the sail profile. In the marked area, the profile changes depending on the wind force. It is precisely this relatively larger area that makes the unique adaptability of the sail possible. However, most of the release area remains within the Tension Triangle. That means, although the profile adjusts continuously, it retains its efficiency and can be easily controlled by the windsurfer.