[Valiente]

That's just a cone drogue, not a series cone drogue.

The difference is that one is a fairly large conical scoop with a springy hoop holding it open and some sort of gap at the end to let the collected water out.

A series drogue, by contrast, is many much smaller cones with a thick line running through them that can extend a couple of hundred feet behind the boat. The idea here is that the load or drag is distributed not at the end, but along the entire length of the line, and it is the cumulative effect that slows the boat. If the first type, due to wave action or just "whipping", leaves the water, your boat will speed up until the drogue "bites" again...lending to a big shock to your cleats/bollards. The series drogue, by contrast, is so freaking long that even if one part is clear of the water, another will be submerged and "biting", as its length is longer than the distance between wave tops.

I'm sure a bird following a boat with a JSD deployed would be tempted to land on the "clothesline" in the trough some hundred feet behind the boat...except for the occasional wave action!

I also concur with Genieskip that I would have both sea anchor and JSD. With a steel full keeler, I can heave-to Pardey style easier than some, and there's a time when I would want to creep at a knot to leeward for a few hours rather than run.