Yes I guess it has similarities but here a Port captain is never a lieutenant-.PCP
Our larger ports are not under the jurisdiction of Jr Officers at all. Comparing the area amount of waterways between coastal Portugal and the entire United States not a realistic comparison. Portugal has less coastline than Florida or Maine . Therefore their will be less ranked officers in charge of some of the minor tribuataries and ports.
Here is a quick refernece to the CG. One of their major missions is SAR and always has been