Lyman et al have had to correct their paper on ocean cooling, as the effect that they observed has proved to derive in part from a bias from “Xpendable Bathy Thermograph (XBT) instruments”. They report
The rapid decrease in globally integrated upper (0—750 m) ocean heat content anomalies (OHCA) between 2003 and 2005 reported by Lyman et al.  appears to be an artifact resulting from the combination of two different instrument biases recently discovered in the in situ profile data…
The second instrument bias arises in data from eXpendable BathyThermograph (XBT) instruments. These inexpensive probes were not designed to provide climate quality scientific data….
The other bias, however, appears to be caused by eXpendable BathyThermograph (XBT) data that are systematically warm [Gouretski and Koltermann, 2007] compared to other instruments. Characterization and removal of this bias will be required before the historical record of ocean heat content can be reevaluated
Perhaps they can now turn their attention to characterizing biases and uses of Recyclable AbathyThermograph (RAT) instruments (formerly known as “buckets”), also a form of inexpensive probe not designed to provide climate quality scientific data, used in an earlier generation of shallow ocean measurements, illustrated below. (As observed by commenters, the earlier generation of inexpensive probes measured shallow (abathos) water and not deep water (bathos)).
Figure: Recyclable AbathyThermograph (RAT) instruments, formerly known as “buckets”.