While much has changed in the field of transportation since the days when the fastest mode of transportation was the horse, one thing that has not changed is the importance of maintaining a stable distribution of weight on cargo ships. While whaling ships don't stagger between the weight of a carcass on each side -- both in the process of butchering and extracting oil -- as they did in the days of "Moby Dick," any ship bearing thousands of tons of cargo must maintain a careful margin when it comes to trim (the difference in height between the bow and the stern) and list (the boat's tilt toward port or starboard).
Stand amidships (at the midpoint between the bow and stern) and look at your inclinometer. Also known as a clinometer, this device will tell you the difference in angle between true horizontal and the plane of the deck. Setting the inclinometer on the deck and comparing its straightedge with the level will tell you the angle and direction of your list.
Note the ship's draftmarks at the fore and aft (near the bow and the stern). These will be a vertical series of numbers indicating the draft, or depth in the water, of that spot on the boat.
Subtract the draft at the fore of the boat from the draft at the aft of the boat to get the boat's trim. A boat "down by the stern" is drafting deeper aft, while a boat "down by the head" is drafting deeper fore.