Editing Walrus-class submarine (section)

==Upgrade program==
[[File:De Zr.Ms. Zeeleeuw in 2014 voor onderhoud op de wal.JPG|thumb|{{HNLMS|Zeeleeuw|1987|6}} being upgraded in 2014]]
In 2007, the [[Cabinet of the Netherlands|Dutch cabinet]] approved an upgrade of the four operational submarines and recruitment of additional crew to improve overall operational availability.<ref name="auto">{{cite web|url=https://magazines.defensie.nl/allehens/2016/01/04_update-walrusklasse |title=Terug in de eredivisie |date=10 February 2016 |last=Twigt |first=André |access-date=23 November 2017}}</ref> The upgrades were focused on near-shore operations and integration with new weapons, and include:
* The migration from the [[Mark 48 torpedo|MK 48 mod-4 torpedo]] to the mod-7 version<ref>{{Cite web |url= https://magazines.defensie.nl/materieelgezien/2016/06/mg201607life-extension-ozb |title= Opknapbeurt voegt dimensie toe |author= André Twigt |date=30 September 2016|website= Materieelgezien |publisher= Defensie.nl |language=Dutch}}</ref>
* Replacing one [[periscope]] with a non-hull-penetrating optronic mast from [[L-3 Communications|L-3 KEO]] which enables the submarine to capture HD footage, both day and night<ref>{{Cite web |url= https://magazines.defensie.nl/materieelgezien/2015/04/04zeeleeuw |title= Beter zicht voor de Zeeleeuw |author= Pieter van Geldere |date=5 June 2015|website= Materieelgezien |publisher= Defensie.nl |language=Dutch}}</ref>
* Addition of a mine and obstacle avoidance sonar by ELAC Nautik
* Refurbishing of the pressure hull<ref name="KA2012KVO">{{cite magazine |last=Kesseler  |first=Andre |date=December 2012 |title=Klaar voor het bruine water |url=https://www.klaarvooronderwater.nl/kvo/Kvo-122.pdf |magazine=Klaar Voor Onderwater |location=Den Helder |publisher=Onderzeedienst Reünistenvereniging |issue=122|volume=35 |pages=11-16 |language=Dutch}}</ref>
* Introduction of a new combat management system<ref name="KA2012KVO" />
* Modifications to support special operations forces

In 2013, the contract for the ''Walrus''-class (IP-W) Conservation Program was signed.<ref>{{cite web|url=https://maritiemnieuws.nl/47167/imtech-marine-ontvangt-meerjarige-opdracht-voor-modernisering-van-onderzeeboten/ |title=Imtech Marine ontvangt meerjarige opdracht voor modernisering van onderzeeboten |date=23 May 2013 |language=nl|access-date=22 June 2018}}</ref> The program covered the preservation of the pressure skin, the replacement of the sonar, navigation periscope and GIPSY combat system, improved communication systems and adaptations to a number of platform systems.<ref>{{cite web|url=https://www.kijkmagazine.nl/nieuws/upgrade-nederlandse-onderzeeboten-van-start/ |title=Upgrade Nederlandse onderzeeboten van start |date=13 May 2013 |last=Kesseler|first=André|language=nl|access-date=22 June 2018}}</ref> The Dutch industry and knowledge institutes were heavily involved in the program via the [[Dutch Underwater Knowledge Centre]].<ref>van Kesteren (2020), p. 13.</ref><ref>Horneman (2018), p. 82.</ref><ref>{{cite web |url= https://www.vno-ncw.nl/forum/verborgen-wapen-onderzeeboten-vol-nederlandse-techniek   |title= Verborgen wapen: onderzeeboten vol Nederlandse techniek |author= <!--Not stated-->|date= 15 May 2017|website= VNO-NCW |language=Dutch}}</ref> It was predicted that the upgrade program would lead to a estimated 400.000 man-hours of work for each boat.<ref>{{cite magazine |last=Booy  |first=Arie |date=September 2012 |title=Maatwerk in een bakbeest |url=https://www.klaarvooronderwater.nl/kvo/Kvo-121.pdf |magazine=Klaar Voor Onderwater |location=Den Helder |publisher=Onderzeedienst Reünistenvereniging |issue=121|volume=35 |pages=9-10 |language=Dutch}}</ref> All four boats were to be modernized by 2019. With the conservation program, the boats can be kept operational until mid-2025.<ref>{{cite magazine |last=Steketee  |first=Menno |date=December 2011 |title=Nederlandse onderzeeboten krijgen een nieuwe toekomst |url=https://www.klaarvooronderwater.nl/kvo/Kvo-118.pdf |magazine=Klaar Voor Onderwater |location=Den Helder |publisher=Onderzeedienst Reünistenvereniging |issue=118|volume=34 |pages=5-8 |language=Dutch}}</ref> The cost of upgrading the four submarines was estimated to be 94&nbsp;million euros.<ref>{{cite web|url=https://marineschepen.nl/schepen/walrus.html#ip-w |title=Instandhoudingsprogramma Walrusklasse (IP-W) |date=10 November 2016 |last=Karremann |first=Jaime |access-date=24 November 2017}}</ref> The first boat to be upgraded was {{HNLMS|Zeeleeuw|1987|2}}, followed by {{HNLMS|Dolfijn|1990|2}}, {{HNLMS|Bruinvis|1992|2}} and {{HNLMS|Walrus|1985|2}}.<ref name="auto"/><ref>{{cite web |url=https://www.iv-groep.nl/nl-NL/Nieuws/Archief-2015/The-first-modified-Walrus-class-submarine-has-been |title=Eerste gemodificeerde Walrusklasse onderzeeboot te water, een mooi project van Nevesbu! |date=December 2015 |access-date=24 November 2017 |archive-url=https://web.archive.org/web/20171201031737/https://www.iv-groep.nl/nl-NL/Nieuws/Archief-2015/The-first-modified-Walrus-class-submarine-has-been |archive-date=2017-12-01 |url-status=dead }}</ref><ref>{{cite web|url=https://magazines.defensie.nl/allehens/2017/11/02_de-ultieme-test-mercuur-en-zeeleeuw |title=Mercuur en Zeeleeuw maken nieuwe start |date=2 November 2017 |last=Perreijn |first=Djenna |access-date=25 November 2017}}</ref> The upgrade of ''Zeeleeuw'' took longer than expected.  Initially the upgrade was expected to have been completed by 2015, but it took until 2016 before the submarine was ready for service again. Currently,{{when|date=March 2024}} ''Bruinvis'' is being upgraded at the [[Den Helder]] naval base.<ref name=HNLMS_Walrus_decommissioned_1/> The Royal Netherlands Navy has also begun to prepare for the replacement of the ''Walrus''-class submarines.<ref name="trouwwalrus">{{cite web|url=https://www.trouw.nl/home/wie-mag-de-grootste-militaire-aankoop-sinds-de-jsf-gaan-bouwen-~ade97bfa/|title=Wie mag de grootste militaire aankoop sinds de JSF gaan bouwen?|author=Marno de Boer |work=www.trouw.nl |date=5 June 2018 | access-date=5 June 2018}}</ref>