A presumably derelict and abandoned boat moored at the San Leandro Marina displays the red white and black of the UFW, the United Farmworkers of America. From the UFW website:
Symbolism In The Flag:
The black eagle signifies the dark situation of the farm worker. The Aztec eagle is a historic symbol for the people of Mexico. The UFW incorporated the Aztec eagle into its design in order to show the connection the union had to migrant workers of Mexican-American descent, though not all UFW workers were/are Mexican-American.
The white circle signifies hope and aspirations.
The red background stands for the hard work and sacrifice that the union members would have to give.