that any additional needed slack may be provided by pulling the leading edge of the pool cover toward the sides further wheel assemblies 54 could be constructed so as to permit horizontal carrier member 50 to be brought flush with pool deck 12 after pool cover 14 is fully extended over swimming pool 10 thereby providing a tighter seal around swimming pool 10 for purposes of illustration the lateral dimensions of cover sheet 16 are greatly exaggerated in fig1 and 5 in actuality cover sheet 16 would typically be transversely enlarged by only a few inches adjacent its leading edge 24 for example in order to cover a 20 foot by 40 foot rectangular swimming pool cover sheet 16 might be about 45 feet long and about 25 feet wide then beginning about five feet away from leading edge 24 the two lateral edges 22 of cover sheet 16 might tend outwardly at an angle of about two degrees such that cover sheet 16 is transversely enlarged adjacent its leading edge 24 by only about four or five inches although such a cover sheet would be acceptable for most rectangular swimming pools it would not allow leading edge 24 to be raised sufficiently to properly cover most odd shaped pools to meet the desired objectives when covering odd shaped pools cover sheet 16 may need to be transversely enlarged adjacent its leading edge 24 by as much as 12 to 16 inches thus beginning about five feet away from leading edge 24 lateral edges 22 of cover sheet 16 would need to tend outwardly at an angle of about six or seven degrees of course it will be appreciated that.