US Flag ships I sailed they were called sounding tubes.
http://www.wosupply.com/index.php/products/marinespecialtyvalves
Attached from the above site:
MAIN_SOUNDING_TUBE.jpg (144.2 KB)
SOUNDING_TUBE_EXP_VIEW.jpg (96.2 KB)
Typically they usually were mostly used on cargo and bulk ships with double bottom fuel oil storage tanks. They were also used in machinery and other enclosed spaces but with a spring powered self closing gate valve with a pipe thread on top to accept a plug if needed.
The top of the sounding pipes were on the open deck or perhaps in a resistor house on the main deck and plugged with a sounding tube bronze threaded plug. The plug had either a centered square recessed opening to match a wrench used to loosen them or a slit not unlike that for a straight blade screwdriver.
http://en.wikipedia.org/wiki/Ullage
Attached: UllageTape.jpg (116.4 KB)
When sounding double bottom tanks, that typically were six to eight feet high, reached by a long pipe from the deck to within a few inches above the bottom of the tank. Typically a steel striker plate was installed beneath the sounding pipe. This is a picture of an expensive 1/2 inch x 50 feet tape. Which for most of the cargo ships I sailed would be too short. The tape has to be long enough to reach from the deck to the bottom of the tank.
http://www.brighthubengineering.com...ry/35372-sounding-the-tanks-of-a-ship/#imgn_4
http://tinyurl.com/ullage
The bottom of the measuring tape has an attached brass bobber. When measuring light liquids typically the bobber would have a pointed end. When measuring thick substances like ships bunker C fuel oil the bobber had an open hollow cup shape on the bottom of the bobber.
Ullage refers to measuring the space ABOVE the liquid level in a tank then using charts provided by the ship builder to determine tank liquid contents.
So you remove the plug and typically wrap it in a small rag and put it in a back pocket of your boiler suit so you do not lose it. Inserting the bobber into the top of the sounding tape you flip over the tape cranking handle and let it fall free.
Listening closely you will hear a 'plop' when the cup hits the top of the liquid perhaps fifty or more feet below and the tape will go slack. Then by quickly pulling up while listening for the 'plop' and gently letting down you get a feel for when the bobber is sitting lightly atop the thick oil. Read the measurement on the sounding tape where the tape is level with the top of the sounding tube and also the deck.
Light liquids like water were measured by rubbing blue chalk on the bottom portion of the measuring tape where the liquid surface is to be expected. Then dropped to the bottom of the tank, then when pulled up the liquid level will be clear. The lighter blue of the dry chalk on top with the now dark blue wet chalk below.
Sounding tapes were used when taking bunkers and just prior to arrival in a port. Some ports wanted to know everything in the way of potable and ballast water, ships fuels and lubricating oils we carried upon arrival. Regardless this information was called for in our log books.
Greg Hayden