Whenever the position of county manager is vacant, the board of commissioners shall designate a qualified person to exercise the powers and perform the duties of manager until the vacancy is filled. The board may designate the chairman or some other member as interim manager; for the interim the chairman or member shall become a full-time county official, and the board may increase his salary pursuant to N.C. Gen. Stat. § 153A-28 (1973, c. 822, s. 1.)