FIG. 8-4 & 8-5 Mastheads used on aluminum masts. The masthead fitting in Fig. 8-4 is intended for jibhead or cat rigs as there is no provision for attaching stays. The mainsheet halyard can be run either internally or externally. Fig. 8-5 shows a fitting for use with masthead rigs. Both main and jib halyards can be run internally.