It is, in fact, a boat anchor. The owner of the frame (a local messenger) has a number of nautical-themed tattoos, so the builder extended the theme to the frame.
Galen Pewtherer San Francisco, CA USA
On 6/14/07, Andrew Musselman <firstname.lastname@example.org> wrote:
> "C'mon Galen -- that thing looks like a boat anchor!"
> Yup, that's what I thought. I figured it's an homage to San Francisco's
> nautical/shipping history, along the lines of this product:
> Andrew Musselman
> Seattle, WA