A Very Slender Vessel is a high speed, wave piercing craft. A standard high speed boat produces an extremely uncomfortable ride over long, high-speed transits in high seas.
A Very Slender Vessel is capable of speeds of more than 60 knots (110 km/h). They are cylindrical, with a small cross-section that can punch straight through waves, rather than going over or through the top of them.
When traditional deep V-hulled boats travel at high speed in rough conditions, they jump from wave to wave and land with high vertical acceleration or g-force. As the speed of the vessel increases or the sea gets rougher, the g-force on landing increases. Peak readings regularly exceed 20 g which is sufficient to cause injury to the personnel and damage to the vessel and its equipment.
It was revealed on 28 May 2015 that N.Korea has under development a VSV attack boat, reported to be deployed on the western side of the Korean peninsular. These were first detected on trials by satellite surveillance late in 2014.