I think when the winds are really heavy
they have less effect. But when the winds are light and especially with an opposing tide the sentinel can really help with "keel wrap".I think that sentinels also help when you need to anchor is a very tight anchorage and are forced to use a reduced scope. After you are sure the anchor is set, it allows you to drop the sentinel to almost the bottom and reduce scope a bit because that big motorboat decided to anchor right next to you !Obviously having all chain is doing the same thing, which is creating a greater cantenary effect. Though not all of us have the luxury of carrying all chain rode.I think the PS article basically implies such. Hereis a webiste that talks about the reasons that a sentinel might help.http://www.johnsboatstuff.com/Articles/anchor.htm.If you have a spreadsheet program (excel) you can also do your own calculations. http://www1.iwvisp.com/download/pub/spreadsheet/anchor.xls.Obviously math calculations are not the same as real world experiences, but its interesting to plug in different numbers, plus changing where you locate the sentinel. When you place the sentinel all the way to the bottom near the anchor it makes a huge difference in the calculated amount of horizontal pull to lift the anchor shank upwards. If you really think about this it really makes no difference in whether an anchor will drag. If its going to drag at a certain tension pull its going to drag anyway (usually a function of the surface area of an anchor not the weight). What a sentinal will do it keep the "SHANK" of an anchor down and that hopefully will keep the anchor from popping up out of the bottom and having to reset again. Typically this only matters when you are on a short scope or the anchorage has some big swellsNot sure if a sentinel is going to do any miracles, but if you in a rocky, boisterous anchorage, or if you are in a tight anchorages with limited scope they seem to help.