Conditions for seafarers vary to extremes based on many factors including the value of their cargo, the type and age of the ship, the business practices of the shipping company, the personality of the Captain and officers, and the ethnic mix aboard ship. We've seen ships with seafarers from nations which were actively at war with one another.
Cargo value determines revenue potential and the profitability of the ship for the owners, and that in turn influences how much money the company has available and may be willing to invest in the capital equipment of the ship.

Bulk cargo ships carry scrap metal, grain, and salt, but the potential revenue is relatively low and often the cargo itself damages the ship. Because of this, ships carrying salt or scrap metal are often at the end of their service life and receive minimal upkeep. And because of the low revenues, sometimes the shipping companies run short of cash and defer payment of wages to the crew. If one of these ships sinks at sea, it and its cargo may be worth more for insurance value than on the open market. Just as the owners cover potential losses of ship and cargo with insurance, likewise they protect themselves against the cost of paying death-benefits to the families of any seafarers who may perish.
Oil and fuel tankers carry a more valuable cargo, and because of the potential environmental damage, these ships receive special regulatory attention among the developed nations. Conditions on these ships tend to be better, but this year will see the end of single-hulled tankers in US Waters, so on those older ships, we now see deferred maintenance issues as they near the end of their service lives.
Car carriers are specialized ships carrying a very valuable cargo which must arrive unscratched and unharmed. These ships are very, very profitable, and one line which comes to Boston offers the crew teak-wood lined dining facilities, a small gym, and a sauna. But because of the expense and high demand for the cargo, these ships only spend a few hours in port, and the crew may only have 20-45 minutes available for shore-leave. That's barely enough time to call home, and without a visiting chaplain, finding phone cards and a phone might be impossible. Because of greater isolation, the crews on these ships experience greater lonliness and psychological-emotional distress.
Cruise ships are the most heavily regulated due to the potential for extreme loss of life and the nature of being floating resorts, but much cleaning and maintenance needs to take place while making short port-calls, so the crews often have very little time to contact home and to conduct necessary personal business. That is why our Boston Seafarers Center becomes vital to the crews of these ships and to the success of the port.
All crew who staff a nautical-operations job (Captain, Officers, Able Bodied and Ordinary Seamen) have under international law a mandated rest period unless in a crisis at sea. That mandated rest period does not apply to the cooks and stewards, who on industrial ships must cook and clean for 30-35 seafarers three meals each day, seven days a week. Neither does it apply to the hotel staff on cruise ships. They legally may be worked 16 or more hours each day, seven days a week.