The Bertram 31 Flybridge Cruiser 1974 vs Bertram Convertible 1985 comparison sits squarely in the category of decisions where specs alone won't tell the whole story — intended use, storage, and long-term ownership costs all factor in.
The power gap is worth calling out. Rated to 465 hp, the Bertram Convertible 1985 has a 325-hp advantage over the Bertram 31 Flybridge Cruiser 1974's 140-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Bertram 31 Flybridge Cruiser 1974 carries 225 gallons versus 3 gallons in the Bertram Convertible 1985. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.
For family outings this is probably the sharpest distinction between the two. The Bertram Convertible 1985 is rated for 12 passengers, while the Bertram 31 Flybridge Cruiser 1974 caps at 9. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Bertram Convertible 1985 could be the deciding factor.
Bottom line: Choose the Bertram Convertible 1985 if your priority is putting more people on the water — it handles 12 passengers and at 42,0 ft it has the deck room to back that rating up comfortably. The Bertram 31 Flybridge Cruiser 1974 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 9 that costs less to run day-to-day.