A barge is \(40 \mathrm{ft}\) wide by \(120 \mathrm{ft}\) long. The weight of the barge and its cargo is denoted by \(W\). When in salt-free riverwater, it floats \(0.25 \mathrm{ft}\) deeper than when in seawater \(\left(\gamma=64 \mathrm{lb} / \mathrm{ft}^{3}\right)\). Find the weight \(W\).