Gunsails Bow Concept

One look at the Gunsails BOW sail tells you it’s different, very different! It has a specially developed mast to go with its radical head design and in contrast to established modern designs, doesn’t have a loose leech. To get the lowdown on the BOW and find out more about its design, we caught up with designer Pieter Bijl.

- Finn Mullen, Pieter Bijl

WS: What is the BOW concept?

PB: The BOW concept is based on a new sail outline with an extreme bend curve at 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. 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 for 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. 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 light handling, the BOW sail is predestined for foiling.