A floating offshore structure, comprising: a buoyant hull (60, 260, 360) including a first column (64, 364), a second column (64, 364), and a pontoon (62, 262, 362) coupled to the first column (64, 364) and the second column (64, 364), wherein each column (64, 364) is vertically oriented and the pontoon (62, 262, 362) extends horizontally from the first column (64, 364) to the second column (64, 364); wherein each column (64, 364) has a central axis, an upper end, and a lower end; wherein the pontoon (62, 262, 362) includes a first tubular member (75, 275) and a second tubular member (75, 275) positioned laterally adjacent to the first tubular member (75, 275), wherein each tubular member (75, 275) has a central axis (76, 276), a first end (75A, 275A) coupled to the lower end of the first column (64, 364), and a second end (75B, 275B) coupled to the lower end of the second column (64, 364); wherein the central axis (76, 276) of the first tubular member (75, 275) and the central axis (76, 276) of the second tubular member (75, 275) are disposed in a common horizontal plane; wherein the pontoon (62, 262, 362) includes a heave plate fixably coupled to the first tubular member (75, 275) and the second tubular member (75, 275), wherein the heave plate extends horizontally between the first tubular member (75, 275) and the second tubular member (75, 275), wherein the heave plate extends axially relative to the central axes (76, 276) of the tubular members (75, 275) from the first ends (75A, 275A) of the tubular members (75, 275) to the second ends (75B, 275B) of the tubular members (75, 275), wherein the heave plate is configured to be disposed subsea to dampen vertical motion of the floating offshore structure. a buoyant hull (60, 260, 360) including a first column (64, 364), a second column (64, 364), and a pontoon (62, 262, 362) coupled to the first column (64, 364) and the second column (64, 364), wherein each column (64, 364) is vertically oriented and the pontoon (62, 262, 362) extends horizontally from the first column (64, 364) to the second column (64, 364); wherein each column (64, 364) has a central axis, an upper end, and a lower end; wherein the pontoon (62, 262, 362) includes a first tubular member (75, 275) and a second tubular member (75, 275) positioned laterally adjacent to the first tubular member (75, 275), wherein each tubular member (75, 275) has a central axis (76, 276), a first end (75A, 275A) coupled to the lower end of the first column (64, 364), and a second end (75B, 275B) coupled to the lower end of the second column (64, 364); wherein the central axis (76, 276) of the first tubular member (75, 275) and the central axis (76, 276) of the second tubular member (75, 275) are disposed in a common horizontal plane; wherein the pontoon (62, 262, 362) includes a heave plate fixably coupled to the first tubular member (75, 275) and the second tubular member (75, 275), wherein the heave plate extends horizontally between the first tubular member (75, 275) and the second tubular member (75, 275), wherein the heave plate extends axially relative to the central axes (76, 276) of the tubular members (75, 275) from the first ends (75A, 275A) of the tubular members (75, 275) to the second ends (75B, 275B) of the tubular members (75, 275), wherein the heave plate is configured to be disposed subsea to dampen vertical motion of the floating offshore structure.