~ Food For Thought ~
I am basing the following on the "assumption" it was intended to support some kind of pole ~ flagpole ~ road crew caution pole ~ awning pole ~ etc. Which it may or may not be. But if it was intended to be used along those lines, consider the following ...
1. If only bored into the ground to the top of the auger threads ~ but still below the bottom hole, it would leave the majority of it sticking out of the ground. Which suggest it would not be very supportive at that depth. Too little "anchor" at the bottom, and too much "play" at the top.
2. However, if that dude was sunk to the "hilt," I suspect it would support just about any type of pole you wanted to put into it ~ including a ten foot flag pole that could waver in the wind all it wanted to and not topple over.
3. But ... Why the long chain that suggest it had a pin attached to it for the "bottom" hole? It leads me to think that whatever was inserted into it may have had an "adjustable height."
4. And what if you used four of them instead of one, and then only anchored them to the top of the augers? And then inserted the shorter legs of a work bench or table? Would four of them used in this manner then give us the support we need. I think it might.
5. Of course, there is still the distinct possibility it was intended for wood - as in a ship deck. But the only way I can see for that to work would be if the wood had a "tap hole" drilled first. Then it would go in easy enough and be secure. But without a tap hole, it would split the wood wide open!
As I said, just food for thought. I am wide open to suggestion. I have been searching the internet, but without the proper wording it's like a merry-go-round. "Aussie auger/anchor" just keeps bringing up the same light-weight variations. Mojjax's auger/anchor looks strong enough to hold up a circus tent! Hey, that gives me an idea. I'll check on that and be back later.
SBB