Gary Fox
N/A
Excellent! Welcome to the forum 
+1 I have had many dinghies come equipped with a folding grapnel. Even if you can lock it well enough to stay open, I never yet saw one that could not be pulled back in as Thinwater describes. Trouble is they fold up so neatly with no piinty bits to damage the boat. the locking ring does keep them shut too!A few years ago I did a test of dinghy anchors. Mantus, Claw, Guardian, Danforth, mushroom, and a fold grapnel type such as the OP posted. The grapnel held so poorly on most bottoms that when testing in shallow water it was much easier to drag the anchor to me than to walk over to it. I gave it back.
Used CQRs on Glenans 5.70s, 8kg, AFAIR, with 10m chain and 30m rope. Held well in the various seabeds around Baltimore Harbour/Roaringwater Bay, but not generally relied on for overnight.I worked at a Sailing School, dinghy sailing, and we cruised with small CQR anchors. Surprisingly they worked well with chain and warp as the dinghy always pulled up head to wind when we anchored in deep bays. I have no idea if it would hold in a blow/tideway but I would assume that it would not. As for the grapnel, I have used that a few times in the rubber duck to stay in one place when fishing; again it digs in and halts the fast drift of the rubber dinghy, snatching the head to wind.