SW108 Southern Wind 108ft Cruising Yacht

The very experienced owner of Kiboko 4, a Southern Wind 108, expects their yacht to improve upon the style and performance of Kiboko 3, a Southern Wind 105, also with naval architecture furnished by Farr Yacht Design. Fast passage-making in comfort and safety with ease of handling and the potential to win superyacht racing events all in a stunning, exceptionally beautiful yacht is the expectation. Starting with the Southern Wind 108 platform, Farr Yacht Design refined the rig, sailplan and appendages for the chosen standard propulsion system with the goal of optimizing the performance envelope for typical Mediterranean conditions and the occasional racing under the ORCsy measurement and handicapping system. Two important design features of Kiboko 4 are generous sail area (607m² upwind, 1288m² downwind, 3.57 SA/WS upwind, 70.7 SA/DISP downwind) for the potential not only to effectively race in light winds but the maneuverability and acceleration to excel in those conditions and high stability (6.2m tapered planform lifting keel, total yacht VCG 0.2m below the DWL). The requirements for the hull are first for it to be an item of beauty and style but contained within it the optimized hydrodynamic parameters to achieve the best speeds. The beam-to-draft has been kept low (6.0) to keep the wetted surface (and thereby the sailplan area) down. The prismatic coefficient (Cp) of 0.555 is maintained from 0° through 15° of heel with a slight reduction to 0.54 at 25° with a precisely designed longitudinal volume distribution. Target stability levels are achieved with a ballast (keel fin and bulb) ratio of 33%. The wide transom is designed with aggressive lift outboard to finely tune the longitudinal trim with heel to maximize effective sailing length, avoid excessive bow down trim and promote good handling in a wide range of wind and sea conditions. The twin rudder arrangement allows Kiboko 4 to be pushed to high heel angles (27° optimum) with exceptional controllability and speed for upwind and reaching while racing. As those same high heel angles are not desirable while cruising the sailplan is flexible and easily depowered with a furling staysail at 55% of the all-purpose headsail sized and the usual multiple mainsail reefs. The full all-purpose jib with single main reef or full main with staysail sail combinations are both well-balanced first steps in sail area reduction and permit the crew a choice depending on the weather conditions. Lastly the owner is moving from a low aspect ratio, fixed keel (4.5m draft) on the previous boat to a high-aspect ratio, lifting keel with a draft range of 6.2 to 4.0m. Not only does the keel design improve performance and efficiency but the 0.5m draft difference will open up many more harbors and cruising destinations.