Designer’s Comments – June 2012
High precision master plugs and long-lasting moulds from Knierim save time and reduce costs in series production of composite yachts
Knierim Yachtbau, located in Northern Germany directly at the Kiel Canal, has a long tradition in boat building and is internationally known for manufacturing high-tech custom made yachts, from pure racers to long-range cruisers and power boats. But it is barely known that Knierim’s know-how is also used by series production boat builders.
Did you know how a new model of a series production boat is developed? Let’s take a closer look at the brand new B/ONE, a 23’ sportsboat by German manufacturer Bavaria Yachtbau. The design of this small race boat, which is supposed to become a one design class, comes from famous Farr Design. Once the concept is final the boat is expected to be launched as soon as possible. To get this done first of all master plugs and moulds for hull and deck have to be built according to the 3D data supplied by the designer.
Knierim offers both, building high precision master plugs and building high quality moulds. The cooperation of Knierim Yachtbau with its experienced boat builders and Knierim Tooling with its well trained technicians guarantees the best possible skills for these jobs. Knierim Tooling is responsible for operating the 5-axis CNC milling machines which, for example, give glued together Styrofoam blocks the shape of a deck or a hull.
Once the Styrofoam is machined to undersize a layer of laminate is applied followed by a layer of epoxy paste. The paste is first rough and then fine machined to give the plug the final shape, precise to a tenth of a millimeter. The surface gets a primer, is sanded and as a final step mirror polished. Now the master plug is finished and ready for use for producing the mould.
Thanks to years and years of experience, highly educated workers and latest technology master plugs can be produced in a very short period. The master plug for the 23-footer needed just 3 weeks from start to finish.
Manufacturing of the mould starts right after the plug is finished. Here again Knierim’s experience in high-tech boat building saves time. Separating layer and gelcoat is spread fast and accurately before a layer of laminate made of glass fibre and resin is applied. Once the steel substructure is attached the mould is separated from the plug. Now, after just 2 and a half more weeks the mould for the hull of B/ONE is finished and the series production can begin. Master plug and mould for the deck are produced simultaneously. It requires a little more effort as it has more edges and corners than the hull and the non-skid surface is inlaid.
Since years Knierim is manufacturing master plugs for all kind of industries and thanks to its experience also complex geometries can be handled. Highly precise and perfectly smooth surfaces combined with the use of premium materials guarantee a superior quality for master plugs and moulds helping to reduce production time and minimize costs.
Designer’s Comments – February 2012
Bavaria B/One – Design #750
The B/One is an exciting, new 7m (23ft) trailer-able, one-design sport boat currently under construction by Bavaria Yachtbau in Giebelstadt, Germany. Bavaria asked Farr Yacht Design for an economical one-design that would impress advanced sailors with excellent performance, yet be easy to handle and operate for the weekend sailor and his/her family. Farr Yacht Design, the designers of the B/One, have met these requirements with a technologically advanced hull shape developed from the Volvo Open 70 and Farr 400, an easy to use sailplan, and interior features you would expect to find on a boat 3 feet longer. The B/One has the power to weight ratio to perform well both upwind and downwind. The 34m2 (377ft2) of upwind sail area is set on an aluminum mast. The 48m2 (517ft2) asymmetrical spinnaker flies on a 1.3m (4.3ft) retractable bow sprit providing plenty of downwind horsepower. The keel and rudder are retractable making docking or anchoring in shallow water possible. The retractable keel also makes slip launching a breeze and allows for very low trailering heights, so that the boat can be towed by a relatively small vehicle. The B/One promises to be an absolute delight to sail and operate with unique features from bow to stern.
Hull and Deck
The hull shape clearly shows the influence, and is a direct descendant, of the Farr 400 and Volvo Open 70 in its full bow shape, broad and powerful stern sections and chined aft topsides. These features combine to provide exceptional speed, optimal balance and solid, dependable handling in all conditions. The maximum beam limit for trailering (2.5m) is seamlessly integrated into the hull and deck detailing to conceal fittings, provide a smooth, rounded deck edge and maximize crew weight stability.
Inspired by the sleek look of larger, modern high-performance one designs such as the Farr 400, the deck is flush with only a slightly raised cabin top to create the necessary headroom down below and contain the required sailing functions on deck. The cockpit is wide and open providing plenty of room for crew maneuvers during racing or seating for friends and family on a weekend harbor cruise. Sail handling is performed without winches or excessive hardware, but still providing all the necessary sail controls demanded by advanced one-design sailors, including adjustable jib tracks and a powerful boomvang. The large, round foredeck hatch provides ample light and ventilation to the interior, and serves as the opening for launching and retrieving the spinnaker via string takedown system. The waterproof companionway cover hinges completely forward providing a large opening to the interior. The cover can also be partially opened to cover the horizontal surface of the companionway while still providing ventilation to the interior via the open vertical surface.
Rig and sailplan
The single spreader, tapered aluminum rig has swept spreaders and does not require a backstay. Calibrated shroud turnbuckles allow for easy and quick tuning changes. The mast is deck stepped for quick and easy rigging. Mast bend is controlled with a powerful 16:1 boomvang. The jib is set on a furler for ease of handling. The square-headed mainsail features a generous roach profile for maximum sailplan efficiency. The bowsprit retracts into an external recess in the foredeck, thereby eliminating the possibility of water ingress into the boat, so common on other boats of this size.
For cruising oriented customers the interior features accommodation for 4. There is a generous V-berth forward and 2 pipe berths with seated headroom on either side of the keel trunk. Space forward of the mast allows for a chemical toilet, while volume below the companionway accommodates a removable cooler. To keep racing weight low, all of the aforementioned interior items, including the joinery for the V berth, are easily removable. The acrylic companionway and keel opening cover both provide ample light to the interior.
The keel/bulb arrangement on the B/One is a T-keel style configuration, as featured on most of today’s high tech racing yachts. The keel’s down draft is 1.65m (5.41ft) and may be raised for docking, anchoring, or trailering to an up draft of only 0.4m (1.31ft). In its raised position the keel passes through a separate opening in the deck, forward of the main companionway, making it possible to completely lock the companionway cover closed thereby securing the boat with the keel raised. The retractable rudder is supported inside a transom mounted cassette and may be raised for docking or anchoring in shallow waters.
The hull shell is hand laminated using E-glass chopped strand mat and multi-axial fabrics over Coremat with additional uni-directional reinforcements used in high stress areas. The deck shell is hand laminated using E-glass chopped strand mat and multi-axial fabrics over a PVC foam core with additional uni-directional and multi-axial reinforcements used in high stress areas. The hull shell support is provided by a simple one-piece structural liner composed of transverse floors and a centerline longitudinal. The keel trunk is integrated into the structural liner allowing for easy movement through the interior.
The B/One is designed and built to maintain a strict one-design standard with a single sail supplier and minimal modifications permitted. All B/One boats will be built by Bavaria Yachtbau, using the highest quality control standards. Farr Yacht Design has drafted the Class Rules to ensure all boats are built and maintained to these strict standards and a level playing field on the race course.