{{Short description|Yugoslav Navy's Una-class submarine}} {{good article}} {{Infobox ship |section1={{Infobox ship/image |image= Mini Submarine, Park of Military History, Pivka, Slovenia (8457057307).jpg |image_caption= Restored ''Zeta'' (P-913) exhibited at the Pivka Military History Park in Slovenia. }}
|section2={{Infobox ship/class overview |builders=[[Brodogradilište specijalnih objekata]] (BSO), [[Split, Croatia|Split]], [[Socialist Republic of Croatia|SR Croatia]], [[SFR Yugoslavia]] |operators= |class_before= |class_after= |subclasses= |built_range=1985–1989 |in_commission_range= |total_ships_building= |total_ships_planned= |total_ships_completed=6 |total_ships_canceled= |total_ships_active= |total_ships_laid_up= |total_ships_lost= |total_ships_retired= |total_ships_preserved= }}
|section3={{Infobox ship/characteristics |hide_header= |header_caption= |type= |displacement=*{{convert|76.1|t|LT}} (surfaced) *{{convert|87.6|t|LT}} (submerged) |length={{convert|18.82|m|ftin|abbr=on}} |beam= {{convert|2.7|m|ftin|abbr=on}} |draught={{convert|2.4|m|ftin|abbr=on}} |draft= |depth={{convert|120|m|abbr=on}} |propulsion=2 × {{convert|18|kW|abbr=on}} electric motor |speed=*{{convert|7|kn|lk=in|0|abbr=on}} (surfaced) *{{convert|8|kn|0}} (submerged) |range= {{convert|250|-|270|nmi|lk=in|0|abbr=on}} at {{convert|3|kn|0}} |endurance= 96–160 hours (depending on number of personnel onboard) |complement=4 + 6 naval commandos |sensors= |EW= |armament=*4 × [[R-1-class swimmer delivery vehicle|R-1]] swimmer delivery vehicles *4 × AIM-70 [[Naval mine#Bottom mines|bottom mines]] |notes= }} }}
The '''''Una''-class submarine''' (also known as '''Type 911''') was a class of six [[midget submarines]] built for the [[Yugoslav Navy]] at the [[Brodogradilište specijalnih objekata]] (English: Special objects shipyard) during the 1980s. They were designed with the purpose of laying small [[Naval mine|minefields]] and transporting naval [[special forces]], with or without their [[submersible]]s, in shallow waters that were inaccessible for larger submarines. Due to their mission profile that called for a small design as well as the need to stay undetected, they lacked torpedo armament and a generator for battery recharging.
During the [[Croatian War of Independence]] and the dissolution of [[Breakup of Yugoslavia|SFR Yugoslavia]], five of the six boats were relocated to [[Boka Kotorska]] where they served with the [[SR Yugoslavia|SR Yugoslav]] Navy. One, ''Soča'' (P-914), was captured in [[drydock]] by [[Croatian Armed Forces|Croatian forces]]. It was later modified and entered service with the [[Croatian Navy]] as {{ship|Croatian submarine|Velebit|P-01|3}}. All of the boats have since been decommissioned.
== Development == During the 1970s the Brodarski Institute (BI) from [[Zagreb]] started working on a new class of submarines for the [[Yugoslav Navy]] (JRM). The project, designated B-91 and led by [[Lieutenant Colonel]] Davorin Kajić, was tasked with developing a class of midget submarines capable of operating in the shallow waters of the northern [[Adriatic Sea|Adriatic]]. Using their small dimensions, the submarines were to be able to maneuver in depths as shallow as {{convert|10|m}}; such abilities were needed to conduct offensive [[minelaying]] near the enemy coastline, [[reconnaissance]], and transporting naval special forces in hostile waters.{{sfn|Podmorničar}}{{sfn|Sušačka revija}}
All six boats were completed from 1985 to 1989 at the Brodogradilište Specijalnih Objekata (BSO) in [[Split, Croatia|Split]], [[Socialist Republic of Croatia|SR Croatia]] and named after rivers in SFR Yugoslavia: ''Tisa'' (P-911), ''Una'' (P-912), ''Zeta'' (P-913), ''Soča'' (P-914), ''Kupa'' (P-915) and ''Vardar'' (P-916).{{sfn|BSO}} Further planned improvements included the addition of a [[Stirling engine]], either by refitting the existing boats or building a new, seventh one, but the imminent breakup of Yugoslavia happened before anything was realized.{{sfn|Podmorničar}}
== Description == [[File:Notranjost podmornice Zeta.jpg|thumb|right|200px|Interior of ''Zeta'' (P-913) after renovation]] The ''Una'' class featured a single-hulled design, measuring {{convert|18.82|m|ftin|abbr=on}} in length with an average draught of {{convert|2.4|m|ft|abbr=on}}. The boats displaced {{convert|76.1|t|LT}} when surfaced and {{convert|87.6|t|LT}} when submerged. Because deploying naval commandos was one of their main tasks, they were equipped with an underwater exit/re-entry chamber.{{sfn|Saunders|2004|p=651}}{{sfn|Brodarski institut - klasa Una}}
Propulsion consisted of two {{convert|18|kW|adj=on}} electric motors, mounted on a single shaft and powered by two battery groups with 128 cells each. The class lacked the ability to recharge during surface drive making them dependent on external power sources such as harbours and [[depot ship]]s. Maximum achievable speed was {{convert|8|kn|lk=in|0}} underwater and {{convert|7|kn|0}} surfaced. Traveling at a speed of {{convert|3|kn|0}} they had a range of {{convert|250|-|270|nmi|lk=in}}.{{sfn|Podmorničar}}{{sfn|Brodarski institut - klasa Una}} Maximum diving depth was {{convert|120|m|abbr=on}}.{{sfn|Brodarski institut - klasa Una}} The sensor suite included an active/passive [[Atlas Elektronik|Krupp Atlas]] [[sonar]].{{sfn|Gardiner|1995|p=645}}{{sfn|Saunders|2004|p=651}}
In accordance with their expected mission, the boats could transport up to six naval commandos armed with 6–12 M-66 or M-71 [[limpet mine]]s. Also at their disposal were four large AIM-70/71 [[Naval mine#Bottom mines|bottom mines]] mounted on the outside of the submarines. Four R-1 swimmer delivery vehicles could be carried in place of the AIM-70/71 mines. With a full crew of six members the boats had an underwater endurance of 160 hours which was reduced to 96 hours if the complement numbered ten personnel (four crew members and six naval commandos).{{sfn|Brodarski institut - klasa Una}}{{sfn|Podmorničar}}
== Boats == {|class=wikitable width=70% |- valign=top ! | Name ! | [[Pennant number]]{{sfn|Gardiner|1995|p=647}} ! | Namesake ! | Builder{{sfn|BSO}} ! | Completed{{sfn|BSO}} ! | Decommissioned{{sfn|Šoštarić|7 August 2008}} ! | Fate |- valign=middle |bgcolor="PaleGreen" |''Tisa'' | | P-911 | |[[Tisza|Tisa]] | align=center rowspan=6|Brodogradilište specijalnih objekata,<br>Split, SR Croatia, SFR Yugoslavia | |1985 | |1997/2001 | |extant; to be donated to the Museum of Science and Technology in Belgrade, Serbia.{{sfn|Srbija dobija podmornicu od CG}} The submarine was delivered to Belgrade in June 2018.<ref>{{Cite web|url=https://www.blic.rs/vesti/drustvo/podmornica-u-beogradu-konvoj-stigao-drumom-iz-boke-a-evo-cemu-sluzi-neobican-poklon/l3j06ke|title = PODMORNICA U BEOGRADU Konvoj stigao DRUMOM iz Boke, a evo čemu služi NEOBIČAN POKLON}}</ref> |- valign=middle |bgcolor="PaleGreen" | ''Una'' | | P-912 | | [[Una (Sava)|Una]] | |1986 | |1997/2001 | |extant; Porto Montenegro Museum, Montenegro.{{sfn|Luković|19 June 2013}} |- valign=middle |bgcolor="PaleGreen" | ''Zeta'' | | P-913 | | [[Zeta (river)|Zeta]] | |1987 | |2005 | |extant; [[Pivka Park of Military History]], Slovenia.{{sfn|Romac|12 April 2011}} |- valign=middle |bgcolor="PaleGreen" | ''Soča'' | | P-914 | | [[Soča]] | |1987 | |2001/2005 | |extant; to be donated to a museum{{sfn|Krnić|25 March 2013}} |- valign=middle |bgcolor="LightCoral" | ''Kupa'' | | P-915 | | [[Kupa]] | |1989 | |2003 | |scrapped in 2008{{sfn|Švel|6 October 2012}} |- valign=middle |bgcolor="Khaki" | ''Vardar'' | | P-916 | | [[Vardar]] | |1989 | |2005 | |fate unknown |}
== History ==
=== Service and decommissioning === [[File:Panovelebit.jpg|thumb|right|''Velebit'' (ex ''Soča'') photographed in the Lora Naval Base in August 2011. Due to modifications carried out by the Croatians after the war, ''Velebit'' is longer than other ''Una''-class boats{{sfn|Brodarski institut - Velebit P 01}}]] All six boats were in service with the 88th submarine flotilla of the JRM with [[Lora Naval Base]] being their homeport. At the start of the [[Croatian War of Independence]] all boats except ''Soča'' were relocated to [[Montenegro]] without participating in combat operations. Croatian forces captured ''Soča'' in drydock at the BSO where it was undergoing an overhaul. ''Soča'' underwent a modification program that improved its autonomy by installing a diesel generator. It was recommissioned, now with the [[Croatian Navy]], in 1996 as {{ship|Croatian submarine|Velebit|P-01|3}} and remained in service until the early 2000s when it was declared redundant. The remaining boats entered service with the new SR Yugoslav Navy. The first ones to be decommissioned sometime between 1997 and 2001 were ''Tisa'' and ''Una''. In 2003 a decision was made that the ongoing major overhaul of ''Kupa'' would stop; the boat was decommissioned and broken up in 2008. It appears that the last ''Una''-class boats in service with the SR Yugoslav Navy were ''Zeta'' and ''Vardar'', both of them being decommissioned in 2005.{{sfn|Šoštarić|7 August 2008}}{{sfn|Saunders|2004|p=650}}{{sfn|Švel|6 October 2012}}
=== Aftermath === Ownership of the decommissioned boats passed on to Montenegro after the country [[Montenegrin independence referendum, 2006|declared independence]] in 2006, ending the state of [[Serbia and Montenegro]] and its joint armed forces. In 2009 the [[Ministry of Defence (Montenegro)|Ministry of Defence]] announced that it is willing to donate three ''Una''-class submarines to former SFR Yugoslav republics of [[Slovenia]], [[Croatia]] and [[Serbia]].{{sfn|tportal.hr|23 February 2009}} Although the "Submariner" society from [[Pula]] was interested in accepting the donation and exhibiting it in a museum, the Croatian MoD responded with a statement that accepting the donation is against national interests; since most of the fleet of the former Yugoslav Navy was relocated to Montenegro at the beginning of the Croatian War of Independence, Croatia claims the military equipment of the former joint armed forces was stolen, and should be a subject of succession. The MoD further explains that the state interest is in compensation for that equipment, not returning "obsolete, damaged and corroded equipment which nowadays Serbia and Montenegro are unsuccessfully trying to sell".{{sfn|Ministarstvo obrane}} [[File:Naval Heritage Collection 06.jpg|thumb|right|''Una'' (P-912)]] Slovenia on the other hand reacted positively to the offer; in 2011 ''Zeta'' was loaded on a truck and transported to Bar, then across Adriatic to Bari, Italy and along Italian coast to Slovenia. Although longer and thus more expensive, sea routes and roads that included crossing the Croatian border were avoided in fear of Croatian authorities confiscating the submarine.{{sfn|Romac|12 April 2011}} P-913 was restored with the help of the "Slovenian Submariners Society" and the [[Military of Slovenia|Slovenian Army]], being officially placed on display at the [[Pivka Park of Military History]] on 17 September 2011.{{sfn|Krnić|17 September 2011}}
In 2013, ''Una'' and a {{sclass|Heroj|submarine|0}} attack submarine, ''Heroj'' (P-821), were restored and opened to the public in the museum section of the [[Porto Montenegro]] marina. The project was initiated by the "Submariner" Society from [[Tivat]] and was, after approval by the Montenegro MoD, financed by Porto Montenegro.{{sfn|Radio Tivat|3 July 2013}}{{sfn|Luković|19 June 2013}} The donation of one of the submarines to Serbia was initiated by the "Submariner" society from [[Belgrade]] in 2009. However it wasn't until five years later in June 2014 that the Government of Montenegro officially accepted the proposal and agreed to cede ''Tisa'' (P-911) to Serbia. The submarine will be exhibited at the Museum of Science and Technology in Belgrade.{{sfn|Srbija dobija podmornicu od CG}}
== Notes == {{Reflist}}
== References == ===Books=== {{refbegin|2}} *{{cite book|last=Saunders|first=Stephen|year=2004|title=Jane's Fighting Ships 2004–2005|publisher=Jane's Information Group Limited|isbn=0-7106-2623-1 |ol=7790644M}} *{{cite book|last=Gardiner |first=Robert |year=1995|title= Conway's All the World's Fighting Ships 1947–1995|url=https://books.google.com/books?id=3hlwQAAACAAJ|location= [[Annapolis, Maryland]]|publisher=[[United States Naval Institute|Naval Institute Press]]|isbn=978-0-85177-605-7 }} {{refend}}
===News reports=== {{refbegin|2}} *{{cite news|ref={{harvid|Šoštarić|7 August 2008}}|newspaper=[[Nacional (weekly)|Nacional]]|url=http://www.nacional.hr/clanak/47102/bitka-za-jedrenjak-jadran|title=Bitka za jedrenjak 'Jadran'|trans-title=Battle for the sailboat 'Jadran'|first=Eduard|last=Šoštarić|date=7 August 2008|access-date=31 January 2014|url-status=dead|archive-url=https://web.archive.org/web/20120716110150/http://www.nacional.hr/clanak/47102/bitka-za-jedrenjak-jadran|archive-date=16 July 2012}} *{{cite news|ref={{harvid|tportal.hr|23 February 2009}}|newspaper=tportal.hr|url=http://www.tportal.hr/vijesti/svijet/10699/Crna-Gora-Hrvatskoj-poklanja-podmornicu.html|title=Crna Gora Hrvatskoj poklanja podmornicu|trans-title=Montenegro giving Croatia a submarine|first=An.|last=S.|date=23 February 2009|access-date=31 January 2014}} *{{cite news|ref={{harvid|Švel|6 October 2012}}|newspaper=obris.org|url=http://obris.org/hrvatska/sudbina-podmornice-p-01/|title=Sudbina podmornice P-01|trans-title=Faith of the submarine P-01|first=Boris|last=Švel|date=6 October 2012|access-date=31 January 2014}} *{{cite news|ref={{harvid|Romac|12 April 2011}}|newspaper=[[Novi list]]|url=http://www.novilist.hr/Vijesti/Svijet/U-strahu-od-Hrvata-Slovenci-podmornicu-za-muzej-dovoze-kopnom|title=U strahu od Hrvata, Slovenci podmornicu za muzej dovoze kopnom!|trans-title=In fear of the Croatians, the Slovenians are transporting their museum submarine by land|first=Denis|last=Romac|date=12 April 2011|access-date=31 January 2014|archive-date=7 February 2015|archive-url=https://web.archive.org/web/20150207204501/http://www.novilist.hr/Vijesti/Svijet/U-strahu-od-Hrvata-Slovenci-podmornicu-za-muzej-dovoze-kopnom|url-status=dead}} *{{cite news|ref={{harvid|Krnić|17 September 2011}}|newspaper=[[Slobodna Dalmacija]]|url=http://www.slobodnadalmacija.hr/Svijet/tabid/67/articleType/ArticleView/articleId/149257/Default.aspx|title=Slovenci predstavili restauriranu podmornicu Zeta, jedino Hrvate nisu pozvali|trans-title=Slovenians presented the restored submarine Zeta, Croatians the only ones not to be invited|first=Denis|last=Krnić|date=17 September 2011|access-date=31 January 2014}} *{{cite news|ref={{harvid|Radio Tivat|3 July 2013}}|newspaper=Radio Tivat|url=http://www.radiotivat.com/index.php/drustvo/49-drustvo/11048-sveanost-u-porto-montenegru-podmornica-qherojq-otvorena-za-posjete.html|title=Svečanost u Porto Montenegru - podmornica "Heroj" otvorena za posjete|trans-title=Celebration in Porto Montenegro - submarine "Heroj" open to visitors|date=3 July 2013|access-date=31 January 2014|archive-date=7 February 2015|archive-url=https://web.archive.org/web/20150207161723/http://radiotivat.com/index.php/drustvo/49-drustvo/11048-sveanost-u-porto-montenegru-podmornica-qherojq-otvorena-za-posjete.html|url-status=dead}} *{{cite news|ref={{harvid|Luković|19 June 2013}}|newspaper=[[Vijesti]]|url=http://www.vijesti.me/vijesti/turisticka-atrakcija-obilazak-podmornice-heroj-tivtu-clanak-134262|title=Turistička atrakcija: Obilazak podmornice "Heroj" u Tivtu|trans-title=Tourist attraction: tour of the submarine "Heroj" in Tivat|first=Siniša|last=Luković|date=19 June 2013|access-date=31 January 2014|archive-date=19 February 2014|archive-url=https://web.archive.org/web/20140219152022/http://www.vijesti.me/vijesti/turisticka-atrakcija-obilazak-podmornice-heroj-tivtu-clanak-134262|url-status=dead}} *{{cite news|ref={{harvid|Krnić|25 March 2013}}|newspaper=Slobodna Dalmacija|url=http://slobodnadalmacija.hr/Dalmacija/Split/tabid/72/articleType/ArticleView/articleId/205826/Stjepan-Lozo-Neemo-odustati-od-Velebita.aspx|title=Stjepan Lozo: Nećemo odustati od 'Velebita'|trans-title=Stjepan Lozo: We won't give up on 'Velebit'|first=Denis|last=Krnić|date=25 March 2013}} *{{cite news|ref={{harvid|Srbija dobija podmornicu od CG}}|newspaper=[[B92]]|url=http://www.b92.net/info/vesti/index.php?yyyy=2014&mm=06&dd=26&nav_category=12&nav_id=868247|title=Srbija dobija podmornicu od CG|trans-title=Serbia getting a submarine from Montenegro|date=26 June 2014|access-date=27 June 2014}} {{refend}}
===Other sources=== {{refbegin|2}} *{{cite web|ref={{harvid|Podmorničar}}|publisher="Podmorničar" Society|url=http://www.podmornicar.hr/default.asp?inc=DivPod|title=Osnivanje i gradnja diverzantskih podmornica klase P 911|trans-title=Developing and building P 911 class midget submarines|access-date=31 January 2014|url-status=dead|archive-url=https://web.archive.org/web/20131213013708/http://www.podmornicar.hr/default.asp?inc=DivPod|archive-date=13 December 2013}} *{{cite web|ref={{harvid|Ministarstvo obrane}}|publisher="Podmorničar" Society|url=http://www.podmornicar.hr/pdf/UstupanjeP_Morh.pdf|title=Ustupanje podmornice od strane Ministarstva obrane Crne Gore Udruzi "Podmorničar" iz Pule|trans-title=Cession of a submarine by the Ministry of Defence of Montenegro to the "Podmorničar" Society from Pula|access-date=31 January 2014|archive-date=24 September 2015|archive-url=https://web.archive.org/web/20150924074818/http://www.podmornicar.hr/pdf/UstupanjeP_Morh.pdf|url-status=dead}} *{{cite web|ref={{harvid|Brodarski institut - klasa Una}}|publisher=Brodarski institut|url=http://www.hrbi.hr/images/files/Brodovi/Diverzantske_podmornice_klase_Una-novo.pdf|title=Diverzantske podmornice klase Una|trans-title=Una-class midget submarines|access-date=1 February 2014}} *{{cite web|ref={{harvid|Sušačka revija}}|last=Freivogel|first=Zvonimir|publisher=Sušačka revija|url=http://www.klub-susacana.hr/revija/clanak.asp?Num=70-71&C=12|title=Podmorničarska tradicija na hrvatskom Jadranu|trans-title=Submarine tradition on the Croatian Adriatic|access-date=1 February 2014}} *{{cite web|ref={{harvid|Brodarski institut - Velebit P 01}}|date=9 December 2013|publisher=Brodarski institut|url=http://www.hrbi.hr/images/files/Brodovi/Diverzantska_podmornica_Velebit_P-novo.pdf|title=Diverzantska podmornica Velebit P-01|trans-title=Special operation submarine Velebit P-01}} *{{cite web|ref={{harvid|BSO}}|publisher=Brodogradilište specijalnih objekata|url=http://www.brodosplit.hr/Portals/17/BSO_reference%2008.pdf|title=Review of delivered vessels since 1980.|access-date=13 March 2014|url-status=dead|archive-url=https://web.archive.org/web/20140313171716/http://www.brodosplit.hr/Portals/17/BSO_reference%2008.pdf|archive-date=13 March 2014}} {{refend}}
{{Yugoslav Ships}}
[[Category:Midget submarines]] [[Category:Ships of the Yugoslav Navy]] [[Category:Croatian Navy]] [[Category:Military of Serbia and Montenegro]] [[Category:Ships built in Split]]