Your tank vessel is loaded down to her marks, and you find that she has too much trim by the stern. Which of the following actions would reduce the excessive trim?

Adding ballast forward is a common practice to correct excessive trim by the stern. When a vessel has more weight towards the rear than the front, it can cause the stern to sit lower in the water, leading to poor performance and handling. By adding ballast forward, you redistribute the weight, elevating the stern and bringing the vessel closer to an even keel.

Loading more cargo forward is less effective in this scenario because the tank vessel is already loaded down to her marks. Adding additional cargo may not be feasible and could potentially exceed the vessel's safe loading limits.

Shifting bunkers forward, while also an acceptable method to address trim issues, focuses on moving existing fuel rather than adding weight. It can be beneficial, especially when there's flexibility in the bunker tanks' arrangement, but it may not sufficiently address the degree of trim if the issue is significant.

Discharging cargo from the after tanks would indeed correct trim, but it requires reducing the overall weight of the vessel. This is a more drastic measure and not always the most efficient solution when adjustments can be made through other means that keep the vessel fully loaded, like adding ballast or shifting bunkers.

Thus, adding ballast forward effectively reduces excessive trim by redistributing weight and helps maintain the vessel's operational efficiency.