A Google search on "Reuben James" "Woody Guthrie" give this: http://www.geocities.com/Nashville/3448/reuben.html (sorry about lack of clicky - I can never seem to make them work) as the first result. There's a photo of the Almanac Singers in 1942 (including Woody and Pete Seeger) and it plays the tune, Wildwood Flower, to which the words were set. (although it's a rather more upbeat version than might have been used for the song)

It says, (amongst other things):

When the U.S.S. Reuben James was torpedoed by the Nazis off the coast of Iceland in late October [1941], killing 86 and wounding 44, Woody was inspired to write a ballad about the incident. He decided the best way to humanize the tragedy would be to name all 86 victims, and he set out to do just that (to the tune of the Carter Family's "Wildwood Flower"):

There's Harold Hammer Beasley, a first rate man at sea
From Hinton, West Virginia, he had his first degree.
There's Jim Franklin Benson, a good machinist's mate
Come up from North Carolina, to sail the Reuben James.

Dennis Howard Daniel, Glen Jones and Howard Vore
Hartwell Byrd and Raymond Cook, Ed Musselwhite and more
Remember Leonard Keever, Gene Evans and Donald Kapp
Who gave their all to fight about this famous fighting ship.

Woody brought his completed work to a songwriting meeting in early November and everyone agreed he'd come up with a sensational idea for a song, but all those names were a bit... boring. You didn't have to go through all that to personalize it, Seeger argued. A rousing agitprop chorus could get the same message across. If you combined a chorus with ballad verses describing the event in detail, it might make a better song. Woody agreed to give it a try and reworked the verses, while Seeger and Lampell developed the chorus that would make the song one of the Almanacs' best-known....

Joe Klein, Woody Guthrie: A Life, London, 1981, p. 209.

I used to sing this song, years ago when I played the guitar. Maybe I'll start again!

Steve