After finding the 3 sunken drydocks, I came back the next week (May 31, 2014) to try taking some video of them. Visibility was much worse this time (about 10'). I followed my compass towards the drydocks, but I seemed to be lost. I found several groups of large cement mooring blocks and chain about 30 feet deep (I assume from anchoring the drydocks). I saw a wall rise up next to one of them, but it was too shallow to be the drydocks I dove last time. It turns out this was a fourth sunken drydock. The top of it was only 20' deep (low tide). The bottom around the far side of it was about 45' deep. This one had more life on it than the deeper ones. The sides were covered with plumose anemones. There was a pile of junk on the top that had more plumose anemones, schools of perch and brown rockfish living on it. A chain and ropes led up to the surface at one corner. I followed it up and there was a big metal buoy just under the surface. Some small floats marked it on the surface. It seemed like they might be submerged at high tide, but at low tide at least, they provide an easy way to find this wreck from  shore.
view from the shore
The pictures below are frame-grabs from the video:
mooring blocks
mooring blocks
plumose anemones on the bottom
mooring blocks and chain
mooring blocks and chain
anemones and stuck jellyfish on the side of the dock
crab trap next to the drydock
another crab trap
anemones on a rope on the drydock
under the hull
corner of the drydock
feather duster worms
blocks next to the drydock
blocks next to the drydock
next to the drydock
under the hull
plumose anemones on the drydock
next to the drydock
perch on top of the drydock
debris on top of the drydock
jellyfish stuck on debris
exposed beams on the end of the drydock
ladder leading down a hatch
pile of debris on the drydock
debris on the drydock
on top of the drydock
on top of the drydock
metal buoy near the surface
small jellyfish
structure on the drydock
jellyfish on the side of the drydock
debris on the drydock
perch on the drydock
blocks on the bottom
plumose anemones on the swim back
red rock crab in th eeelgrass