You will not use a stern anchor very often. Last year during our 6 months ( only spend 2 week at a slip ) we did not use one, the year before maybe 2 times. most often they are used in the open road stead where you may get a swell different from the wind. We have a Tayana 37 that we have an Danforth style about 18 lb. could probably use a 13, It is use for just keeping the boat pointed into the waves. We have about 10 feet chain to 1 inch nylon strap that is on a reel. If I need to lay to 2 anchor ( never happen in Mexico so far) I would use one of the bow anchors. It is rare not to be anchoring in sand.