I had good luck using a campsite picnic table on the Orcas trip, but I had to go to trees during a Sucia Island adventure.
First, I tried to anchor in the camp area - after giving the tent folks prime real estate because they needed it. That put me at the edge of the cleared site. Near/beyond the cleared perimeter, the ground wasn't very compacted. The Boom held (twice) just long enough for me to relax - then laughter from the tent crowd as one stake pulled out. I was near brambles so didn't have a lot of "try over here a bit", room and I forgot LowTech's technique of favoring the stronger anchor.
So I move out to the picnic table above the beach - still close enough to be "with the group". But unlike the "sitting on dirt" tables on the Orcas trip, this table was on beach pebbles (A.K.A. marbles). It slid about 5 inches when I got in the hammock. I'm pretty sure, given the inertia of the table, that two stakes, anchoring the far end of the table, would have been plenty.
But I was done fussing around. I noticed a fine grove of trees (you start doing that when you become a hammock camper), down the trail from the tent site. Though I would no longer be "with the group", at "Hammock Time" everyone is going to sleep anyway. So I set up in those trees and was fine.
Ravenin - I'm going on about that because, sigh, that's what I do, AND so you'll see that just putting a boomstake or Orange Screws or other pegs in the ground, or tying to other objects, might not get the job done. I don't want you to be surprised if you get in your hammock, just start to relax, and all of a sudden ... your world changes a bit. Just get out of the hammock, laugh at your fate, and figure out what you need to do to make a more solid anchor.
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