The concept is based on static and dynamic ballast, and the fact that (sea) water is 850 times heavier than air. Beside the shape and width of the hull, as well as 1000 kg of useful cargo positioned mostly below the water line, primary stability is maintained by two 350 L side tanks/keels. They also minimize the boat making leeway. When the boat heels by 14°-15°, the windward keel fully emerges from the water while the leeward “RIB- float” begins to submerge. If required water can be pumped at 2 × 100 L/min from the leeward submerged keel to the windward tank which takes stern part  of a rigid core of “RIB-float”. All four oblong tanks have transverse bulkheads and are constructional elements of the hull. By using pumps and water ballast the total stability is almost doubled. It is the same as having a windward canted keel with a 160cm long fin and a 1300 kg bulb. When heeling at 35° the stability is highest; comparable to having a 150 cm long windward canted keel with a 2200 kg bulb. One should bear in mind that water displacement is less than 3000 kg and draft is only 40 cm. During incident gibe when water gets caught inside the 'wrong' tanks, the soft part off leeward RIB -float still provides 700 L of buoyancy on a 1m limb. Considering that heeling over 120° leads to negative stability, a 25-50 L airbag triggers on top of the mast to prevent the boat from capsizing. In this way it remains at approximately 100° horizontal position with possibility of self-righting. Shifting water partially or fully from lower tanks to upper ones can be used to change the amplitude of rolling and possibly minimize interference with side waves.