Shoals 20 miles south east of San Clement Island

[moosacreek]

We just had a harrowing experience on an overnight sail from San Diego to San Clement Island. All of a sudden at 3 am the depth dropped to as low as 12 feet about 20 miles south-east of San Clemente island. It was not on the NOAA chart and it scared the hell out of me. Does anyone have experience with this? Why is this not on the charts?

[billknny]

Originally Posted by moosacreek

We just had a harrowing experience on an overnight sail from San Diego to San Clement Island. All of a sudden at 3 am the depth dropped to as low as 12 feet about 20 miles south-east of San Clemente island. It was not on the NOAA chart and it scared the hell out of me. Does anyone have experience with this? Why is this not on the charts?

Because what you saw was a shoal.... of FISH.

Let's apply a bit of Occam's razor analysis:

Which is more likely:

#1: An "uncharted" reef of 2 fathoms or less rising from the bottom in 500 fathoms of water un-noticed and uncommented on in some of the most frequently sailed waters in the world...

Or

#2: A problem with my instrument.

Or

#3: Something between the bottom of my boat and the bottom of the sea that reflects my sonar back before it hits the bottom??

If you vote for #1, I have a great alien abduction story for you. Completely true, promise.

[Zai]

You probably sailed over a big ball of bait fish, which showed up as the bottom on the sounder.

Just saw billknnys post. Thumbs up!

[gamayun]

Also known as "phantom depth" or deep scattering layer. Google it. It's pretty cool stuff

[cyan]

Originally Posted by billknny

#1: An "uncharted" reef of 2 fathoms or less rising from the bottom in 500 fathoms of water un-noticed and uncommented on in some of the most frequently sailed waters in the world...

In all fairness there IS a spot of about only 34 fathoms about 20 miles South East of San Clemente. Ask any local fisherman who brings in bluefin.
Plus you missed possibility #4: They were blown off course and it was more like South WEST of San Clemente...Cortes Bank! (yikes)

[Don C L]

South WEST is Cortes Bank, but otherwise, yeah school of something. I saw that once off Santa Rosa Island when, in a black calm sea in the wee hours an enormous cloud of green light lit up under my boat and swirled around very fast. It was pretty startling and it took me a minute to realize it was a school of fish stirring up the bioluminescence!

[cal40john]

A more exciting version would be a sub almost surfaced under you.

[Don C L]

That would be a better story, dang it!
I actually thought it was a whale for a while till it didn't come up to breathe.

[cyan]

There IS a NOAA buoy around that location. (don't hit it. that would be bad. can't say how I know that.)
Could it have sunken to 2 fathoms deep?
Has anyone checked on 46086 recently?

[moosacreek]

Thanks to all of you for your comments. We are just beginners and still have lots to learn. It's nice to know there is a forum for doing that with people that will take the time to respond.
Best,
Hank and Su Kraus

[jimglasair3]

Originally Posted by cal40john

A more exciting version would be a sub almost surfaced under you.

Big Grin! When qualifying as a periscope operator on my boat, I had to make a number of "approach and attack" runs on targets, with sailboats being the favorite in the caribbean... it was all about the eye candy usually on deck

It was a bit of a challenge to see how close we could get, and shiphandling at slow speed, especially with some of those keels...

I am quite certain some of those soundings would have had the attention of anybody watching