KUTIN BATTENS in SAILMAKING Inverness, 02. Feb. 2014 / Ljubljana, 12. Nov. 2014 Development of sails is unseparately connected with introduction of new materials for sailing boats, rigs and particularly for the sails. We are fighting against the weight. If we look at two identical boats in identical circumstances - the lighter will be faster. The sail material needs to be strong enough to resist unrecovered stretch. For maximum efficiency the sail need to be adjusted for any wind direction and wide range of wind strengths. The sail shape is adjusted with controlled deformation of the rig and material of the sail. When the deformations on the rig and the sails are uncontrolled the efficiency is worse. Stronger (less stretchy) materials are easier to control. Strength of the sail (and rig) is in direct relation with the weight for the given material. With improved construction of the sail (and rig) we can make it lighter or more controllable or both. The rigid sail is lighter but the shape control is more limited. Because of limited shape control it is suitable only for limited sailing environments. Soft sail shape is controlled basically only by pull - action (tension). Semi-rigid or rigid sail is controlled by push (compression) and pull (tension). Push & pull control of the sail, associated with proper rig design, give more efficiency and less weight of complete rig at the same shape control range. With increased boat and wind speeds the demanded control of the rig translates increased stress into whole boat. The peak stresses on the boat sums up and give a limit to the power of the rig for particular weight. The only way to increase the same boat s speed is in more efficient use of the materials concerned. With the soft sail pulled (tensioned) to the limit the shape control is possible only through the bending of the rig. The only push (compression) on the soft sail is administered with the compression of the sail battens. Sail batten compression control is not efficient because of the large distance between the attachment points. When the batten is attached all the way, the push (compression) action is possible on any point along the batten. When batten is attached all the way the stress on the attachment points is distributed all the way. The Kutin batten shape and position on the sail is not limited to the shortest distance between the edge attachment points. With the proper design the soft sail get push and pull (tension & compression) control, stable shape with lower stress peaks translated to the rig and the whole boat. Because the stress of the sail is contained, there is overall less weight and better shape control at the same time in all kind of the sailing activities. Miha Kutin univ.dipl.ing.
VELCRO BATTENS & BOARDS Inverness, Scotland, 17.04.2013 Velcro batten is new product. It consist basically of thin carbon composite or similar strength material, covered on one side or on both sides with hook / loop type tape, with possibility of wrapping whole batten (or edges only) in some protective cover and stitching Velcro afterwards through the thickness of the batten. The purpose of the batten is to prevent thin membranes from collapsing when loaded with compression force. The purpose of Velcro is to spread the forces from the holding points at the batten ends to the whole length of the batten. The advantage is stronger and lighter membrane construction with multiple advanced development possibilities particularly with technically demanding products like sails and saddles. Velcro battens were foregone first successful testing as a sail battens and saddle frames. The advantage, when included in construction of tents, sun shades, biminis, spray hoods, rucksacks, collapsible kayaks / dinghies and many other products are still forthcoming. Sail battens Sails need battens to: - Gain area with bigger roach. - Stiffen membrane at low wind speeds against the movements of the boat and at turbulent air flow with higher airflow speeds. Additional functions for Velcro battens only: - Reinforcement - prevention against stretching of sail material in the direction along the batten and eliminating a need for balancing tensions in sail material along the batten with the halyard forces. - To give and gain at sudden changes in the air flow speed. - Changing cross shape of the sail with acting on batten only. - Sail construction with the inner tension lines where battens are holding attachment points inside the sail. - Batten as a luff batten in free flying sail also instead of torsion luff rope. - Batten as a pre stretching and reinforcing luff batten at other sails. -Leach batten for increased efficiency, inner strength and stability of the sail.
Consequences in comparison with standard battens: - Overall less tension on sail membrane at the same drive force with all the advantages of light and stable sail. - Sail trim without comparison. - No need for batten end fittings and heavy reinforcements at the batten end area. - The necessary stiffness of the battens much lesser with the consequence of easy sliding around the rigging and possibility of furling. - Port and starboard battens with sail membrane in the sandwich in between where big roach demands more stiffness - Less stress on the rig due to inner strength and stability of the sails with the better sail shape control. - Construction of light off wind sails with battens. - Construction of furling sails with horizontal battens. - Off wind furling sails with improved shape and furling ability with not pre tensioned halyard. - Much less tear and wear. - Improved boom furling ability. - Sail repairs are simplified. - New life to used sails.
Pic 1 Picture 1: Mini 650 with standard sail wardrobe (thanks to unknown author of the photo). Velcro batten can be attached in an envelope along the luff of the asymmetric spinnaker instead of the luff rope. The sail shape will be more under control and furling or even reefing is possible. Jib with full length VB will gain couple of m2 on the top, where it is important, without hindered tacking. Mainsail with VB can be lighter with more trim and shape control. Mast sliders, especially at the headboard will be much less loaded with smooth reefing and less luff tape chafing at the sails without sliders.
Pic 2 Picture 2: First VB prototype mainsail, tested on 650 Nm trip over North Sea. It is the beginning of the innovation. Pic 3 Picture 3: The same sail running at about 30 knot wind.
Saddle frames: Saddle frames have the same structure as the sail battens. They are made of carbon prepreg composite, wrapped in leather or other suitable material, with Velcro stitched on and through, before it is hardened in the oven. Materials excellent strength / weight ratio and simple adjustment of desired shape, elasticity and flexibility, give the designer wide opportunity for innovative work. Pic 4 Picture 4: One of only few saddles made with carbon flat frame. Tania H. Olsen won gold on World Championship 2009, gold again on VC 2011, and bronze on VC 2011 at another discipline. Bronze 2013
Technology: Prepreg composites are used in wide assortment of parts for air plane industry, bicycles, boats, F1 cars, tennis rackets, skies and many other products. There are also sails and rigging made from the same material. All this products need pressure and heat to consolidate and reach designed strength. The temperatures are low and easy controllable, but the squeezing is more technically demanding. That is the reason that the majority of products, where economy is on rule, don t get adequate treatment. VB technology is simple and affordable and with more people involved there will be also more knowledge and fresh ideas. Miha Kutin univ.dipl.ing