[xoxoxoBruce]

I looked at another anchoring video which had some interesting comments.

What if anchor stuck in seabed .

If the anchor stuck in the sea bed and the ship is not able to draw it out, usually the chain is cut and a buoy marker is left attached to the other half of the chain which will go with the anchor so that it can be retrieved later.

I was a 3rd Mate back in the 80's and we all got told it is the weight of the WHOLE CHAIN that holds the ship from dragging , the anchor simply holds the chain in place.

That's correct

2 questions though... How much cable to be paid out for it to hold and how one will know that its actually holding but not drifting?

The anchor chain length will depend on the depth of anchoring point. The thumb rule is "Scope of 6" i.e. if the depth is 25 m, the anchor cable to be paid out 150m. The Ship should move in a fixed diameter and that should not change....however, in case of wind, there can be a small drag.

How do you de-anchor to release ship to run ? Or how do you release the ship from the seabed taking off the anchor?

The windlass or anchor winch is used to wind up the chain and lift the anchor. If the anchor is stuck, the ship is moved aft and ahead to release the anchor (which is unlikely as ships are anchored in dedicated anchor stations where such problems do not occur).

Aha, so that's why they need near 1,000 ft of chain.