The Zodiac Mark I ST 2009 vs Zodiac Open 5.5 PVC 115hp T-Top On Order 2021 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 115 hp, the Zodiac Open 5.5 PVC 115hp T-Top On Order 2021 has a 90-hp advantage over the Zodiac Mark I ST 2009's 25-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load.
Both boats are rated for 5 passengers — a good fit for a family of four or five plus guests. Comfort at capacity is another matter; the longer hull typically means more seat options and better weight distribution.
Bottom line: The Zodiac Open 5.5 PVC 115hp T-Top On Order 2021 at 18,0 ft is the right call if deck space, comfort, and entertaining are top of your list. The Zodiac Mark I ST 2009 at 11,5 ft wins on trailering ease, likely lower purchase price, and simpler docking — a solid choice for a buyer who wants more boat for less money.