I am wondering how much longer the RMS Titanic could have remained afloat if the crew had allowed the ship's anchor and anchor chain to fall to the bottom of the ocean immediately after the ship had hit the iceberg. (I am not even sure if a ship's anchor chain can be unfastened from a ship, but let's just say for the sake of this question that it can be unfastened.)
The combined weight of Titanic's anchor and anchor chain was approximately 116 tons according to this Wikipedia article:
"...In 1911, the company manufactured the anchors and chain for the ocean liner RMS Titanic. The largest of the anchors weighed 15.5 tons and on completion was drawn through the streets of Netherton on a wagon drawn by 20 shire horses. The chain and fittings for the anchors weighed around 100 tons..." https://en.wikipedia.org/wiki/N._Hingley_%26_Sons_Ltd
Since the Titanic went down bow first, and the anchor and chain was located in the bow section, immediately getting rid of 116 tons in the bow section would have increased the time it had remained afloat before it sank.