There's plans to replace the larger 1000-ton Schwedeneck class of three ships at WTD71 as well within the next few years - for about 137 million, although that's not proceeded far enough to fall into the current stimulus package. There were previously considerations to outsource WTD71's fleet to external contractors instead, mostly when FDP was still a part of the government.
Overall Plans for the trials boat fleet renewal in this regard are, based on an March 2020 news article and April 2020 inquiry answer from the government:
- two new STS "Security, Transport and Tug" boats (20m length) for 13 million Euro (tender started in 2019)
- four new SVK "Sea Trials, Coast" boats (50m length) for 60 million Euro by 2023 (tender for two started in 2020, third option to be bought from Corona Aid, fourth not secured yet)
- six new SVS "Sea Trials, Sea" boats (65m length) for 420 million Euro (!) by 2025 (not tendered out yet)
- The 20m STS class would replace three existing Type 743 workboats (AM6, AM7, AM8) bought in 1971 that do general duties in e.g. towing target ships or placing materials or supporting ships and divers in trials at sea. Third vessel is considered superfluous and for the old workboats is only maintained due to downtime stemming from age.
- Four boats of the 65m SVS class would be assigned to the Navy in general, not WTD71. These would be a direct replacement of the four Type 905 Todendorf class security boats (29m length) used to secure the Putlos coastal training grounds on the sea side against civilian ships and maritime mammals. For the purpose SVS is probably quite a bit oversized, so there may be new duties involved here as well.
- Two boats of the 65m SVS class would replace two Type 748 Schwedeneck class vessels (57m length). These larger trials boats are in recent years regularly deployed to e.g. Norway to assist in German trials there, hence procuring a similar-sized, slightly larger class for such purposes.
- The four 50m SVK class vessels would replace a third vessel of the Type 748 Schwedeneck class, the two boats of the Type 745 Stollergrund class (39m length) and the trials boat Wilhelm Pullwer (32m length, built 1966) with a unitary, relatively cheap class of ships.
Of the replaced classes one Schwedeneck, one Todendorf and two Stollergrund were previously decommissioned and sold. These serve with the Lebanese Navy (the Todendorf as a patrol boat), the Israeli Navy (a Stollergrund as a trials boat) and demilitarized for two civilian research institutes in Germany and Israel (the Schwedeneck and a Stollergrund). In general these three classes, built around late 80s to mid 90s, are still considered worthwhile ships, although they're getting a bit old.
The only other ship that WTD71 runs in its "Maritime Support Center" outside of these replacement classes is the large trials ship Planet, a 3,850-ton SWATH vessel built in 2005. Any other boats - there's some workboats for survey work - will be cut.
The sizes chosen for SVK and SVS as well as the strong hints of basing it off available commercial designs and the inhouse experience with Planet suggest to me a possible relatively straightforward buy of SWATH vessels from Abeking & Rasmussen with possible competition from TKMS. A&R has sold three 61m SWATHs and a 50m SWATH as pilot baseships, TKMS has sold two 49m SWATHs to customs (run with the borderguard). Size- and tonnage-wise this would present a massive jump from previous fleets btw, we'd be talking 2,000-ton vessels here.
The two "fleets" of WTD71 and Putlos are usually not mentioned in line-ups of the German Navy, but have traditionally been earmarked in a wartime reserve role as patrol boats since the 70s. In regular service the ships are unarmed (outside Planet's torpedo launchers).