by Saturday (November thirteenth) the marine technicians demonstrated a device for us, that scientists use to collect data called eXpendable Bathy Thermograph (XBT). XBTs are designed to fall at a known rate, and therefore used to measure the water temperature based on depth and create a temperature profile. Its often used to verify that the depths reported by the boat’s multibeam sensors are as accurate as possible. This is because sound from the multibeam can travel at faster or slower speeds depending on the temperature and density of the water, occasionally giving an inaccurate reading.
An XBT is shaped like a missile. The head is made of lead to allow the probe to drop at a measured constant rate. Within the probe’s plastic housing lies a coil of copper wire that sends the temperature signal back to the ship’s computers. The probe is launched from a small gun like launcher, where the other end of the wire is then attached to the gun. Once launched, the copper wire begins to uncoil as the probe drops and uses an electronic circuit to take temperature readings. Once that limit has been reached, the wire is cut by hand and the probe is gone forever :(. The data is transmitted in real time and monitored by a marine technician in the ship’s computer lab. There are a variety of probes for different depths. They can range from $100-$1000 a prob and are manufactured by Locke-head Martian.
We found this really interesting because of how they work and how often they are used. Once, one of the marine technisians was telling us that they were on a trip where they had to launch one of the XBTs every 15 minutes! That’s just insane and the amount of money that would’ve had to cost, since you can’t re-use them.
We’d like to say a big THANK YOU to the R/V Thomas G Thompson marine technicians Liz and Jen for sharing this amazing technology with us!
Leilani R. Combs (Seattle central college)
Zak Carter-Schwedler (North Seattle Colleges)
