Most of the times when something like that is done,,then
a) they had a problem before departure,, engine and/or other mechanical, like rudder etc
b) they are known for problems, means a history for it, like black outs before for example
on the Mississippi river I saw same with another ship and asked the pilot,,that bulker had
two break downs on the river the last 3 visits and is now required for the next 3 visits to have escorts. Pretty expensive matter btw
brgds
capt ted