Kobaya is a term for a type of smaller military style vessel that is fast and maneuverable. Highly ornate versions of these and larger military vessels called Sekibune were used by Daimyo and their clans for ceremonial and other official purposes. I don’t know about the smaller ones, but the larger ones were called Gozabune.
Ship modelers building American or European subjects are accustomed to finding detailed drawingsfor the more popular of these vessels. There are even large numbers of plans made specifically for ship modelers. But, unlike with western subjects, there is a dearth of plans of Japanese watercraft. I’ve found plenty of sketches and there are basic line drawings that might be used, but these commonly don’t have the information needed to build a proper model.
One reason for this is that Japanese boatbuilders don’t have a tradition of recording their work, and they generally only make temporary drawings on wood, sometimes destroying them when done.