First of all, Kudos to you for giving GMAT 4 times and improving your score!
I am not aware of any specialization in shipping and logistics and I wonder why you are looking at such a narrow field for specialization. An MBA degree as such is a broad based general management degree, with option to specialize in one or many fields. With your interests you should consider specializing in supply chain management and learn about all aspects of SCM- logistics being one. This will make you good to join any industry, including shipping.
Many b-schools are known for their SCM specialization - Smeal Business School, Arizona Carey, Tepper, Purdue Krannert, Ross, Michigan State University (Broad) to name some. Rotterdam Business school has a Masters in Logistics Management. You should take a decision on what you want to do? An MBA course with general management perspective and specialization(s) or an MS with immersion in the subject of your interest?
Do get back to us for discussing your profile further.