Forbes has a short post suggesting we may see a spike or at least a continuation of the high level of self propelled semi-submersible activity in 2020. The article is by H I Sutton, who’s blog, Covert Shores, is on my recommended blog list.
Sutton has come to suspect that use of these vessels has become a status symbol among drug smugglers. There is also a suggestion that we might expect more of them bound for Europe.
I would note that movement from Brazil to Africa, crossing where the Atlantic is at its narrowest, might make sense as well.