FSX – Martin SP5B Marlin Flying Boat flight2000it 11 years ago FSX – Martin SP5B Marlin Flying Boatt. This was a twin engined piston powered flying boat entering service in 1951 and servin into late 1960s with the United States Navy for naval patrol. By Kazunori Ito. Converted to FSX by Michael Pook. 7.5 MB – FS2002/FS2004 Martin SP-5B MarlinFSX – Douglas A2D Skyshark UpdateFSX – British Heavy Fighter Westland Whirlwind Updated