These are custom made by my nephew (about 20 pounds each). we both run drifters and have anchored in stillwaters for steelhead and salmon for years. sometimes anchoring in water as deep as 40' what we like to do in say 15' of water is let the front anchor (spiked) out first and let out at least 40 to 50 feet of rope, drop the back anchor and pull back and set the anchors where the boat is in the middle of the ropes.
What this also does is allow you to get a rod under the anchor ropes when a fish goes under them (both anchor ropes at a 45% tilt) many times with an anchor rope straight down if a fish goes around or under the boat to the other side you have to take 9' of rod and try and stick it straight down to go around the rope to play the fish without getting the line broke from the rope. With your ropes at a 45% angle it is much easier on the line and "rods" also in the wind the anchors will slide a little while digging in so after 15 minutes or so you pull the slack up to tighten the boat again.
I use a regular drift-boat anchor in rear and the spiked one up front and always have the spare spike anchor on board. encase a heavy wind comes up I can change the back anchor to a spiked one if need be. also on long trips I have a cylinder - spiked anchor that weighs at least 60 pounds I take when I'm going on week long lake trips so no wind can ruin my day short of a tornado!
As far as weeds we found that if you drag the anchor it will load up with weeds and now will not "STICK" to the bottom, the weeds wrap around the anchor making it a lot larger and taking away sharp edges and making the spikes worthless. we found that not dragging the anchor and setting it right where you drop it (with rope at angle) works much better. The stronger the wind the more angle of the rope.