ABOARD THE SEA DRAGON, 1,000 miles east of Japan — After narrowly avoiding a typhoon, battling seasickness and being pelted by rain for days on end, crew members aboard the Sea Dragon were galvanized by the sight of a stranded boat.

The 150-pound piece of a skiff, torn in half and adorned with Japanese characters, was most likely a remnant of the tsunami that struck eastern Japan last year.

This scientific expedition was unusual in many ways, including the fact that it didn’t contain any scientists. Members of the volunteer crew hailed from six countries and lived on a yacht for a month in hopes of finding an array of debris they could photograph and blog about.

They are part of a citizens’ brigade that has been fanning out along the West Coast and in the Pacific, collecting and categorizing thousands of items that were swept out to sea after an 8.9-magnitude earthquake sent a tsunami crashing into coastal Japanese communities in March 2011. In some cases, they are tracking down and returning items to their owners.