Q.Are you allowed to discharge ballast that had not undergone mid ocean exchange in port? (Our vessel is trading in the Fareast. Ports are very close to each other)

Ballast water is the talk of the town these days. Come 08th September 2017, the ballast water convention will enter into force.

And with that, there will be more and more inspections focussing on how we manage ballast water.

To avoid violation issues, it is important that we are sure of what is expected of us with regard to ballast water.

Ballast water convention requires that

1. A ship conducting Ballast Water exchange to meet the standard in regulation D-1 shall:

.1  whenever possible, conduct such Ballast Water exchange at least 200 nautical miles from the nearest land and in water at least 200 metres in depth, taking into account the Guidelines developed by the Organization;

.2  in cases where the ship is unable to conduct Ballast Water exchange in accordance with paragraph 1.1, such Ballast Water exchange shall be conducted taking into account the Guidelines described in paragraph 1.1 and as far from the nearest land as possible, and in all cases at least 50 nautical miles from the nearest land and in water at least 200 metres in depth. 

However as per Article 3 of the ballast water convention these rules of Ballast water convention does not apply to

ships which only operate in waters under the jurisdiction of one Party and on the high seas, unless such Party determines that the discharge of Ballast Water from such ships would impair or damage their environment, human health, property or resources, or those of adjacent of other States;

So in your case, I am not sure how close your ports are and if these ports are in one country. If these ports are close and are in the same country, ballast water exchange would not be required.

However if these ports are in different country, each country in this case has their own ballast water requirements for such cases.

For ship coming from Brazil and bound for Argentina have specific instructions for ballast water exchange.

In any case, your ship's agent would have instructions about any specific ballast water requirements for ships arriving from nearby ports.