The switch to the improved Boeing B-50 Superfortress meant that the USAF found itself with a surplus of barely used B-29s. In a complex inter-service deal, 60 of these aircraft were passed to the US Navy, for conversion to very long range patrol aircraft. Initially flown in “standard” B-29 configuration, they were returned to Boeing for conversion to the maritime role. Turrets were removed, an AN/APS-20 search radar was installed, along with other improvements, including a sonobuoy dispenser and MAD boom.
Entering service as the P2B-2S, the type served with a number USN units, covering the East and West coasts of the USA.
As more modern types entered USN service as replacements, a number of the P2B-2s were passed onto allied nations, serving with some of these secondary users into the early 1970s.
As an aside to the Boeing conversions, a similar program was undertaken in the UK, with help from Bristol Aviation. Surplus Washington B1s were converted to Washington MR1s. Like the US conversions, turrets were removed, and a search radar installed No MAD boom was fitted, as the Washington MR1 was seen as an interim type that would shortly be replaced by new built Shackleton MR2s. In RAF service the Washington MR1 saw service until 1961, which unsurprisingly turned out to be longer than initially planned.