Sentinel

sentinel - A weight suspended from the anchor line (rode) to help stop the anchor from dragging in rough weather.
serving - Protecting or covering part of a line to stop wear.

sentinel
A weight hung from the anchor chain in order to keep the anchor lying as flat as possible to prevent dragging.
separation zone ...

Sentinel - Extra weight attached to the rode that is lowered halfway down to pull the anchor line further down
Set - Direction that the current is flowing towards or a boat is drifting ...

Anchor sentinel: A separate weight on a separate line which is loosely attached to the anchor rode so that it can slide down it easily. It is made fast at a distance slightly longer than the draft of the boat.

perdue: per-du or per-due (per-d¡¹, -dy¡¹) noun Obsolete. A soldier sent on an especially dangerous mission. [From French sentinelle perdue, forward sentry : sentinelle, sentinel + perdu, past participle of perdre, to lose (from Latin perdere).] ...

An anchor sentinel (weighted dolly, kellet) is a weight slid partway down the anchor rode in order to increase the anchor's catenary, or sag, which improves the anchor's holding power.

the Pathfinder, Patrol, Sentinel and Skirmisher, of about 2900 tons displacement, and 25 knots speed; 370 ft. long, with engines of 57,000 I.H.P., and carrying ten 12-pdr. and eight 3-pdr. Q.F. guns as well as two torpedo tubes.