I am told that you can get away with an OVERSIZE Danforth or Bruce-type anchor. So, if you normally use an 8# Danforth, go up to 13# or 16#. The issue apparently is a combination of 2-4 MPH of current and gravelly bottom, which Danforths and Bruce anchors have a tough time with. Lots of guys also run a couple drift anchors, which put extra tension on the anchor.
You don't need a float to raise your anchor, but you do need something to mark your rode and make it more retrievable if/when you have to "get off the hook" in a hurry to work a fish. Most guys use a float to raise their anchor because they use big herkin' 26-40# "Columbia River" anchors. Nobody wants to haul something that heavy by hand.
Interestingly, the use of very heavy anchors has led to the belief that chain is unnecessary, and even a detractor when using a float puller. The typical Columbia River float puller uses a 1-way rope gripper that runs down the rope, but stops when it gets to chain. So, if you have 10' of chain, your anchor will still be 10' down after the float has done its work. The traditional SS hoop doesn't work in this case, because the anchor is so heavy that it just runs back down once the water pressure on the float is gone. Yo would have to use 20-30# of chain to get the SS hoop to work correctly. Also, nobody likes the deafening cacophony of chain on aluminum.
I ended up making my own "Columbia River" anchor. It's real pretty. The tines are bent in a graceful arc instead of that crude angle, and I painted it fire-engine red just for fun. It weighs 32#, not counting the 10' of 3/8"chain. I love chain. Big chain. No fancy float-puller for this guy either, just haul it in by hand.
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Regards.
Finegrain
Woodinville