Float-Sink Transition
Definition
The shift from negative to positive buoyancy in an immersed body as putrefaction gas accumulates in the body cavities. Typically occurs 5 to 14 days post-mortem in temperate water; 2 to 5 days in tropical water; 3 to 6 weeks or longer in cold water below 10°C.
- Cause
- Putrefaction gas accumulation in body cavities
- Temperate water
- 5 to 14 days
- Tropical water
- 2 to 5 days
- Cold water below 10C
- 3 to 6 weeks or longer
Common questions
Why does the float-sink transition timing vary so widely by water temperature?+
Putrefaction is a bacterial process that proceeds faster in warmer water, generating gas that offsets the body's negative buoyancy sooner. Cold water slows bacterial activity substantially, so gas accumulation and the resulting shift to positive buoyancy takes far longer.
Can the float-sink transition alone establish a reliable post-mortem interval for a recovered body?+
It gives a wide contextual window rather than a precise interval, because water temperature, depth, clothing, body mass, and scavenging all affect timing. Investigators use it alongside other post-mortem interval indicators rather than as a standalone estimate.
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