A system and method are for transferring fluid cargo between a cargo vessel and a cargo connection point at open sea where the cargo vessel is required to keep an end portion of the cargo vessel up towards the resultant element force direction, wherein at least one self-propelled buoy, that is designed to be in fluid connection with the cargo connection point, is connectable to a side portion of the cargo vessel, there being a cargo line that is connectable between the self-propelled buoy and the cargo vessel, and where the self-propelled buoy is designed to keep the self-propelled buoy within predetermined radial distance boundaries from the cargo connection point also when it is attached to the cargo vessel.