Sweden will refit the two A17-class submarines Sodermanland and Ostergotland with Stirling-Mk3 air-independent engines. Four Swedish boats (the three A19s of the Gotland-class and the A14 submarine Nacken) have an earlier Stirling-Mk2 engine which allows them to cruise submerged for two weeks without surfacing or snorkeling. The refits for the two A17s will take three years; the boats will be ready for testing by 2004, by which time Nacken will be retired. This will leave the Swedes with five ultra-modern diesel boats with air-independent engines. The two A17s will actually be cut in half and lengthened by 10m to make room for the Stirling engines. The Mk3 engines will have increased efficiency, power, and noise reduction, and will be able to operate at greater depths. --Stephen V Cole