15' of chain ? No wonder you need to use 10:1 scope. For normal coastal , harbour stuff we use 35 metres of chain. While I'm prepared to let it all out plus the line if necessary we sit more than happily to 3:1 . That's in conditions from 'mill pond' up to 'who was the idiot who chose this anchorage'. Beyond that we have needed 5:1 on a couple of occasions.
Previous boat had less chain and more line and we did drag on a few occasions. With Raven we have never dragged, even in conditions when others were being dragged all over the shop.
(PB set a Danforth. ptooey. Now CQR and more than happy.)
Unless it's to reduce weight I cannot understand why you would use only 15' of chain when it's the chain that does most of the work.
"Do you think God gets stoned? I think so... Look at the platypus." Robin Williams.