First of all, I would like to thank WhyMe for allowing me (some time ago already) to post it in this thread.
History of Polish minesweepers wouldn't be complete without small minesweeping boats.
Theoretically first units of this class in the Polish Navy were four ex-German small landing craft of the Pionierlandungsboot type that were adapted for that purpose in 1946. In reality, hovewer, they never actually served as such. First of them was lost in transit from shipyard to its base on 30th of november 1946, while rest of them served only in auxiliary duties.
First real minesweeping boats of the polish navy were Soviet-designed wooden riverine minesweepers of the '151' type (TR-40). They were license-produced in Poland between 1954 and 1956 - 7 for our Navy and 47 for for USSR (initial plans called for 22 ships for Poland and 49 for USSR). Also, some sources mention that 8 hulls were sold to Romania where they were finished as VD-241 to VD-248. Despite being officially "riverine" units, in Polish Navy they actually served on the Baltic Sea - initially in the Gulf of Gdańsk (based in Hel) and from november 1956 in the Pomeranian Gulf (based in Świnoujście). Their transit between the bases was made through inland waterways (Wisła, Noteć, Warta and Odra rivers) and was basically the only part of their service actually on the rivers. Their service lasted until 1970, when they were struck and later scrapped, except for two boats (TR-42 and TR-47) that served for about a year as auxiliary units (renamed K-12 and K-13 respectively).
In the 1956 Northern Shipyard in Gdańsk undertook a mass production of the Soviet-designed boats of Project '361' (K-8). In total 201 such boats were made, 60 of the '361S' variant (initially designed as communications and medical-evacuation boat) and 141 of the '361T' variant (minesweeping boats). Poland used 51 such boats. 21 in the Coast Guard (10 '361S' and 11 '361T'), 4 in the civilian maritime administration (based on '361T') and 26 in the Polish Navy, including one as diving support boat and 25 ('361T') as minesweepers. They entered service in 1958 while last four were struck in 1986. In 1978 one boat was sold to Cuba and in 1984 four to Nicaragua.
Last ships classed as minesweeping boats (or, to be more precise: "minesweeping cutters") in the Polish Navy so far are two vessels of the B410-IVS design (NATO: Leniwka), built in 1983 in Ustka Shipyard. They were based on civilian fishing trawler B410 (73 ships in several variants built for civilian operators in Poland and abroad) and their primary duty was refresher training of the sailors from the fishing fleet that in time of war would be mobilized as auxiliary minesweepers. Both these craft were struck in 2005.