Jim, that one was a case of an Evolutionary vestige, Carver-style. Go to the Carver web site and look at all the interesting .PDFs of the 1950s/60s/70s and 80s. Its a great corporate history lesson, but also will give you the clues as to the models. The "2x" series was a sedan, such as the 3120 Voyager, 3326 Voyager, 2826 Voyager - same hull as the corresponding 3180 Monterey, 3396 Mariner, 2986 Mariner, but above the gunwales, a very different boat. So when the '80s came along, the 2826 Voyager and 2896 Mariner shared the same hull. Then along came the "x7" series, the all fiberglass hulls. Carver offered two layouts in the 28 foot range, as before, although the deck, hull and cabin sides were the same, the interiors were different, so to keep consistent with history the 2827 remained the Voyager and the 2897 remained the Mariner...
A car-based analogy would be the Buick Riviera, Oldsmobile Toronado and Cadillac Eldorado. All 3 were quite distinct from each other in the 1960s and early 70s, but by 1979 they were essentially the same car with different trim...