Perhaps another explanation would be to check on battery operating temperature???

I believe that is full of sea men.

i am wondering if it is a joke or a practice?:haha:

Hi!

The original website says the thermometer is weighted, and it has an attachment point for a retrieval line, so I would guess that it is intended to be dropped over the side of a ship to measure the temperature of the water.

For a U-boat, I think the application would be to measure water temperature in order to better estimate the density of the water, which the U-boat must take into account when trying to maintain a specified depth in the water.

BTW, there is a North Atlantic thermocline that is associated with the Gulf Stream (see http://cdiac.ornl.gov/oceans/glodap/...haline.web.pdf) that exists within the U-boat operational envelope, but it does not appear that U-boats took any conscious advantage of it.

Pablo

Weems and Plath hand-held thermometer - the head's wrapped in leather which I suspect could be wetted and used in a similar fashion to a wet-bulb sling psychrometer to determine humidity/relative humidity. Judging from the lanyard, NOT submersible (see, "salinity thermometers" for submersibles)!

Have to say, just a small bit off-topic but there are some amazing artefacts/memorabilia/items, collectables (call them what you will) on that site from O.P.

:woot:I suspect this man may be on the right track

We have a winner here :)

Ocean temeprature was probed regulary to determine its density.

There is some evidence, from the stories told by uboot sailors, that they knew that in certain regions going deep would render the active sonars inneffective. This observation might have stemmed from personal experience. Ie a sub would dive very deep to avoid depth charing and notice that the escorts started dropping bombs in the wrong place or pinging in circles like they lost their contact.

The website this image appears on describes the large object as a weight.

A problem I see with caine007's theory is that the crew lowering the device would have no way of seeing the gauge change when it hit a thermocline or a thermal layer, so they wouldn't know at what depth they encountered it. The reading is not relayed back to the surface in real-time. The only useful information it could bring back is a minimum or maximum temerparture, which could be achieved by using sliding pins in the tube - as in gardenening thermometers.

To determine the temperature cross section of the first 200' or son, the thermometer would be lowered and raised several times to increasing depths, say at 3 meter intervals, and the min/max temperatures noted.

Seems a bit long-winded, especially if the u-boat is fitted with a a thermometer or a bathythermograph...why not just dive and monitor the temperature changes?

Of course it cannot be used as a bathythermograph. But to determine salt water density for adjusting trim tanks it would fit the job

How can you measure salt-water density with a thermometer? I don't see how temperature comes into it.

I think it is because the less dense the body of water, the colder it becomes.....

Most of the heat energy of sunlight is absorbed in the first few centimeters at the ocean's surface, which heats up during the day, and cools at night (as heat energy is lost to space by radiation). Waves mix the water near the surface layer and distribute heat to deeper water, such that the temperature may be relatively uniform for up to 100 m (300 ft), depending on wave strength and the existence of surface turbulence caused by currents. Below this mixed layer, however, the temperature remains relatively stable over day/night cycles. The temperature of the deep ocean drops gradually with depth. As saline water does not freeze until it reaches −2.3 °C (colder as depth and pressure increase) the temperature well below the surface is usually not far from zero degrees. [1]
The thermocline varies in depth. It is semi-permanent in the tropics, variable in temperate regions (often deepest during the summer), and shallow to nonexistent in the polar regions, where the water column is cold from the surface to the bottom. A layer of sea ice will act as an insulation blanket.
In the open ocean, the thermocline is characterized by a negative sound speed gradient, making the thermocline important in submarine warfare, because it can reflect active sonar and other acoustic signals. Technically, this effect stems from a discontinuity in the acoustic impedance of water created by the sudden change in density.
When scuba diving, a thermocline where water drops in temperature by a few degrees Celsius quite suddenly can sometimes be observed between two bodies of water, for example where colder upwelling water runs into a surface layer of warmer water. It gives the water an appearance of wrinkled glass that is often used to obscure bathroom windows, and is caused by the altered refractive index of the cold or warm water column; these same schlieren can be observed when hot air rises off the tarmac at airports or desert roads and is the cause of mirages

Temperature and the amount of salt present are two seperate variables. You cannot determine one from the other. However, both varibale scan be used to calculate the density of the water.

If you know the temperature of a water sample, and know the salinity density of the same water sample, then you can use those two variables to calculate the density of the water sample, which can then be used in a further buoyancy calculation. This final calculation could then enable the crew to predict the trim tanks settings.