About this detail of the Tiger
Every Tiger 1 had at least two drain valves in the hull floor. They were used to remove liquids (usually rainwater) from inside the vehicle.
This photo of vehicle #250031 (at APG museum) shows an open drain under the front right hull  . The same drain is visible in a photo of hull #250002 [1, see page 89] , the second vehicle in the series.
These diagrams show the position of the front drain, between the first two torsion bars. The stiffeners on the hull floor had small holes allowing spilt liquids to reach this corner. The drain had a handwheel for manual operation.
This photo shows hull #250122 in Bovington museum, during restoration.
Each drain consisted of a 60mm diameter hole sealed by a moving disc. The disc was supported from a bracket welded to the floor  .
The disc had a rubber rim so that it was waterproof when tightened up.
Here are the dimensions  of the handwheel and the bracket.
At first there was no cover on the front drain, so it was accessible to the radio operator. But it could be damaged by his feet. A protective cover was added [1, see 18.104.22.168] starting with vehicle #251075 in April '44. The photo above  shows the cover. It is hinged and opens to the right.
The Tiger Lubrication Chart shows three drains on the hull floor, numbered (6). It states that they should be inspected every 500 km.(The latest version of this article)