Michael,

PEHU would be the one that you can get the most information on. I have U 57's KTB describing the sinking and can e-mai a scan if you'd like.

NORWEGIAN was mined and the U-boat that laid the mine, UC 43, was torpedoed and sunk with all hands by a Vritish submarine while homebound. Most of the surviving documentation would be British.

As for CRESCENT CITY, I can't find a WWI loss by that name. There was a CRESCENT CITY (2105 grt, built 1870) that was wrecked on or near Galley Head in 1871. Could taht be the ship you're thinking of?

Best wishes,
Michael