a sailing and rowing vessel of the XI XIX centuries. They were built in settlements located along the White Sea coasts, the lower Dvina and in Siberia. They were durable, had got double planking and round lines making them look like a nutshell. Some koches reached 25-meter length. They served for distant voyages and nearshore navigation in the Arctic Ocean, for cargo transportation and trapping. Scientists have still not come to the common conclusion regarding constructive features of this vessel type.