Technology and Operations
This forum is for discussing technological & operational matters pertaining to U-boats.
Re: Thermal Layers
Posted by:
ROBERT M.
()
Date: July 16, 2004 09:26PM
Kurt. et al:
Bathythermograph (BT)
A device develpoed by Althestan Spilhaus in 1938 to measure
temperature/depth profiles in the ocean, the BT was basically a reworking of a most unworkable device called an "oceanograph"
built in 1934 by Carl-Gustav Rossby for the same purpose. It consisted of an open, rectangular frame in which a compressible bellows with a pen arm and stylus was mounted at one end. The stylus rested on a smoked glass slide and moved across it to scratch a record of ocean temperatures. The stylus also moved vertically with changes in depth and thus created a temperature/
depth profile.
The BT was further improved by Maurice Ewing and Allyn Vine in 1940. They recognized that knowledge of the sub-surface ocean temperatures would be equally valuable to submarines in avoiding Sonar detection. If a subsurface temperature gradient existed. a submarine could hide in the "shadow zone" and be immune from Sonar. Their version responded more quickly to temperature changes and was streamlined so it could be lowered and raised more quickly from a moving ship than could the previous more unwieldly version. In 1940 WHOI (Woods Hole Oceanographic Institute) started doing military research for the government, a
large part of which was concerned with Sonar and the use of BTs with it. Knowledge of the vertical temperature structure of the ocean was extremely helpful to Sonar operaters since sound speed in sea water is a strong function of temperature, and various
types of vertical temperature profiles woud lead to sound traveling
differently in the ocean. BT data was also useful for adjusting the
buoyancy or trim of submarines since it could help provide an
estimate of how much ballast would be needed to move a submarine from periscope depth to greater depths. A strong thermocline would require much more ballast for the submarine to descend.
The military research also led to further improvements in the BT including better aerodynamics for more stable operation at higher speeds as well as moving the glass slide and stylus from within the BT to inside the submarine. By early 1943 many submarines were
outfitted with and used BTs. In an extremely helpful quid pro quo, the glass slides were given to WHOI and Scripps Institute after
missions in both oceans, allowing charts of the vertical temper-ature structure of the ocean to be constructed. Over 60,000 slides
from the North Atlantic alone were thus made available to ocean-
ographers.
The area of detecting temperature/depth is from -2.2 to 32.2 degrees Celsius. The BT may be fitted on a surface ship or submarine. During the measurements, the ship's (or the submarine's) speed can be up to 22 knots, normally up to 12 knots.
Go to:
www.beyonddiscovery.org/content/view.pdf.asp?a=219 to read "Sounding Out the Ocean's Secrets"
[www.fleetsubmarine.com] "The Sub
marine Bathythermograph"
Also, go to "google" and type in "SSXBT" to see how far along BTs
have come. You can also type in "Sippican, Inc." the company
that manufactures this advanced equipment.
Regards,
ROBERT M.
Bathythermograph (BT)
A device develpoed by Althestan Spilhaus in 1938 to measure
temperature/depth profiles in the ocean, the BT was basically a reworking of a most unworkable device called an "oceanograph"
built in 1934 by Carl-Gustav Rossby for the same purpose. It consisted of an open, rectangular frame in which a compressible bellows with a pen arm and stylus was mounted at one end. The stylus rested on a smoked glass slide and moved across it to scratch a record of ocean temperatures. The stylus also moved vertically with changes in depth and thus created a temperature/
depth profile.
The BT was further improved by Maurice Ewing and Allyn Vine in 1940. They recognized that knowledge of the sub-surface ocean temperatures would be equally valuable to submarines in avoiding Sonar detection. If a subsurface temperature gradient existed. a submarine could hide in the "shadow zone" and be immune from Sonar. Their version responded more quickly to temperature changes and was streamlined so it could be lowered and raised more quickly from a moving ship than could the previous more unwieldly version. In 1940 WHOI (Woods Hole Oceanographic Institute) started doing military research for the government, a
large part of which was concerned with Sonar and the use of BTs with it. Knowledge of the vertical temperature structure of the ocean was extremely helpful to Sonar operaters since sound speed in sea water is a strong function of temperature, and various
types of vertical temperature profiles woud lead to sound traveling
differently in the ocean. BT data was also useful for adjusting the
buoyancy or trim of submarines since it could help provide an
estimate of how much ballast would be needed to move a submarine from periscope depth to greater depths. A strong thermocline would require much more ballast for the submarine to descend.
The military research also led to further improvements in the BT including better aerodynamics for more stable operation at higher speeds as well as moving the glass slide and stylus from within the BT to inside the submarine. By early 1943 many submarines were
outfitted with and used BTs. In an extremely helpful quid pro quo, the glass slides were given to WHOI and Scripps Institute after
missions in both oceans, allowing charts of the vertical temper-ature structure of the ocean to be constructed. Over 60,000 slides
from the North Atlantic alone were thus made available to ocean-
ographers.
The area of detecting temperature/depth is from -2.2 to 32.2 degrees Celsius. The BT may be fitted on a surface ship or submarine. During the measurements, the ship's (or the submarine's) speed can be up to 22 knots, normally up to 12 knots.
Go to:
www.beyonddiscovery.org/content/view.pdf.asp?a=219 to read "Sounding Out the Ocean's Secrets"
[www.fleetsubmarine.com] "The Sub
marine Bathythermograph"
Also, go to "google" and type in "SSXBT" to see how far along BTs
have come. You can also type in "Sippican, Inc." the company
that manufactures this advanced equipment.
Regards,
ROBERT M.
