Abstract: An arrangement and method for restraining surge and sway of the barge during floatover of a topside onto a substructure. Roller bumpers provided on the substructure guide the barge during slot entry and exit without the use of secondary mooring lines and restrain sway at the floatover position. Dedicated vertical bearing surfaces are provided on the substructure at the entry to the slot. Resilient bumpers are provided on the barge. The resilient bumpers engage the dedicated vertical bearing surfaces on the substructure and position the barge in the floatover position in the longitudinal direction. A tug boat tows the barge into the slot until the resilient bumpers engage the dedicated vertical bearing surfaces. The tug continues to pull throughout the floatover operation to hold the barge in the floatover position.