I would recommend going the Jacques Cousteau route.
Remember his famous oceanographic research vessel
Calypso?
The one he sailed around the world dozens of times in, and which featured in all those National Geographic Specials?
OK, maybe that dates me a little, but the point is this... Calypso started life as Mine Sweeper HMS J-826, launched March 21 1942, and built by Ballard Marine Railway Co, Seattle, WA.
# Displacement 270 t.
# Length 136'
# Beam 24' 6"
# Draft 8'
# Speed 15 kts.
# Complement 32
# Armament: One 3"/50 dual purpose gun mount, two 20mm mounts and two depth charge projectors
# Propulsion: Two 800bhp General Motors 8-268A diesel engines, Snow and Knobstedt single reduction gear, two shafts.
She was a wooden-hulled minesweeper built for the Royal Navy. She was commissioned into the Royal Navy in February 1943 as HMS J-826, and assigned to active service in the Mediterranean Sea, reclassified as BYMS-2026 in 1944, laid up at Malta and finally struck from the Naval Register in 1947.
After World War II she became a ferry between Malta and the island of Gozo, and was renamed after the nymph Calypso, whose island of Ogygia was mythically associated with Gozo.
The Irish millionaire and former MP, Thomas Loel Guinness bought Calypso in 1950 and leased her to Cousteau for a symbolic one franc a year. Cousteau restructured and transformed her into an expedition vessel and support base for diving, filming and oceanographic research.
http://www.youtube.com/watch?v=FEETL5KcJ10
So... a converted 200dt-400dt military ship would do the trick... provided by a rich patron... perhaps an alumnus of The Imperial Academy of Science & Medicine (JTAS #22), or some other wealthy/noble enthusiast, thus providing for lots of "directed adventures" (the patron has acquired documents hinting at an Ancient site that is currently unknown, and wishes you to investigate, etc).
This would allow you to create - for example - a militarized Fat Trader (with uprated engines & weaponry), which the PC can get customized for scientific purposes.
Or a modified Dosonov 400dt Survey Scout, with down-rated engines (J2 only), and 30dt of fuel tanks converted to equipment/lab bays (leaving 80dt for the J2 and 18dt for extended PP running in long-duration operations).
I would personally create a TL 12/13 version of a Dosonov for the base design of the ship... nothing says "military surplus" like lower tech levels!
