The Woodie (or "Woody") is a part of the 1960's southern California surf culture. However, one would normally not expect to have to slow your boat to let one pass! This one, however, follows San Diego Yacht Club races as a spectator/photographer. I've visited their web site and still can't figure it out!
Woodie. San Diego, California. January 1, 2016. Greg Gillson.
I encountered this "boat" on the afternoon of the 2016 SDYC New Years Day Race. However, I and about 55 other bird watchers were participating in the 2016 San Diego Field Ornithologists New Years Day pelagic birding trip. We were aboard a more typical ocean-going vessel.