At work I found the arms of the Nigerian Ports Authority in an ad in the Journal West Africa. Unfortunatly I doesn’t know much about this arms obviously its has maritime conections and the Stars on the Dolphins was the Badge of Nigeria during colonial times, it also was incorporated into the badge of the Cruiser HMS Nigeria.
I may be speculating but I believe that the three interconnected "C" charges are traditional West African iron ingots that also served as trade money and decorations. The form of these particular ingots are of a necklace called a Manilla Collar made in a style used by British traders. See this article for more information: http://www.coincoin.com/I062.htm
<div class=“bbcode_center” >
http://www.henrycollection.org/pics/082-jbh.JPG
</div>
It seems like a good guess David. As traders use Ports it would be a nice symbol to use.