Trimaran sailplan. They contribute to drag when heavily immersed, and their level of immersion indicates when to reef. Two types of trimaran exist: the regular trimaran and the open trimaran, which features a trampoline between the hulls instead of plating. Trimarans have a number of advantages over comparable monohulls (conventional, single-hulled sailboats). Given two boats of the same length, the trimaran has a shallower draft, a wider beam, less wetted area, and is able to fly more sail area. In addition, because of the righting moment provided by the wide beam, trimarans do not need the weighted keel that is required
Pontoon bridge innovation, in 1708 a Swedish army used a leather pontoon bridge to cross a river before the Battle of Holowczyn French general Jean Lannes's troops built a pontoon bridge to cross the Po river prior to the Battle of Montebello (1800). Napoleon's Grande Armée made extensive use of pontoon bridges at the battles of Aspern-Essling and Wagram under the supervision of General Henri Gatien Bertrand. General Jean Baptiste Eblé's engineers erected four pontoon bridges in a single night across the Dnieper during the Battle of Smolensk (1812). Working in cold water, Eblé's Dutch engineers constructed a 100-meter-long pontoon bridge during