Thanks skipper 9 for your comments. I had 150' of anchore line on the anchor / boat, but had only used 100 feet as per the rule of thumb: 3 times the depth. Your advice does make sense, especially relative to anchoring off the stern. I really need to totally understand this. Three people, but all of which were pretty good size, over 700 lbs total. Boat with low walk out door and gap of 2" under door as designed, pretty calm day as you can see from the pictures. I am still not sure if it was one wave or just one that finsihed us off. After the boat is reviewed in detail for drain lines being connected, etc I will post the experts opinion's such that the viewers can learn as I will and hopefully this never happens to anyone else. We cut the anchor line with a pair of scissors. cost us 30 seconds for not having a knife on my belt. knot was too tight to untie quickly by then. This boat has perch fished like this many times before, but maybe not with this much weight (maybe 150lbs more?)