# Angel Effectiveness

An "angel" or "sentinel" or "kellet" is a weight that is deployed down the anchor cable to increase the holding power of the anchor, by lowering the catenary of the cable. In effect, it is "virtual scope."

In this page I attempt to model the effectiveness of an angel, by calculating the "effective depth" of the water. By this I mean that by putting the angel down, I change the depth from being 50 feet in reality, say 30 feet effectively.

Here's the equation:

$d_{effective}=h-d sin(atan\frac{h}{l}+atan\frac{w}{t})$

where:

w = weight of angel

t = anchoring force

h = real depth of water

d = length of pennant to angel

l = length of rode