It has probably been said on this board before, but from just glancing through the replies here : the chain is not supposed to be used to add extra weight. The whole idea of the anchor chain, and then the use of anchor rode, is so that you 1) have a manageable way to prevent rode chafe in areas you may anchor where there are rocks or coral or unforeseen items which may chafe and cut your anchor rode, thus loosing your anchor and 2) allowing your anchor a more horizontal line so that it is more easily able to set into whatever bottom you have anchored.
Sorry, but anyway. (And yes, I''ve anchored to watch fireworks and parades and such in very, very crowded areas. I''ve also anchored to have lunch.) Maybe wouldn''t have responded if I had not currently been in retail, and trying for 3 days to tell people that the cute little mushroom anchors they want to use tied onto a 50 foot polypropolene line will not provide immediate anchorage in the current of the 50 foot deep river here. (Can''t be more than 50 feet, why do I need more than 50 feet of rope?)