#7: Real World -- large pieces !




Time for real world test !

So far, we had used small samples about half-inch-cubed to look at sinking behavior. To investigate practical conditions, we checked the sinking in the pressure tank with a large piece, about 4 x 4 x 4 inches redwood piece.  Previously, small samples had sunk in a minute or two at 200 PSI.  The large sample was allowed to sit at 200 PSI for 15 minutes and then pressure increased to 400 PSI.  After about 6 minutes at 400 PSI, or 1100 ft depth, the large piece sank. We concluded that for large pieces, 800-900 ft depth would be sufficient to reach P(min).

Finally, we went to sea on a boat.  We took a redwood log (picture above) about 2 ft diameter and 2 ft tall and sank it in the ocean at 1000 ft for 30 minutes. We did not have the equipment to detect live sinking in the ocean, but when the log was brought back up to the surface, it sank, confirming we had reached P(min).  After 5 minutes, it floated, indicating that P(max) was not reached. 

When working in the ocean, it is much easier to lower the wood to deeper depths than to wait a long time for it to sink. So, we have determined that quickly lowering to the most depth possible is the quickest and cheapest way to sink wood.


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