AKA"keltie". You don''t want it sitting on the
anchor-- the whole purpose of the sentinnel is to increase the catenary in your
anchor line,(which increases the holding power of your
anchor)therefore, I would try to put it somewhere close to halve the distance between your bow and the bottom-possibly even more, you will have to play with this. I am also assuming that you are using a combination chain/rope
rode for your
anchor line. I am not sure however if you will be able to prevent keel wrap All the time by using a sentinnel. 20lbs of lead should be more than adequate, assuming you are using a properly sized
rode. Hope this helps.