100

The New 100 That Followed the 90

The Ocean Alexander 100 is a 30.53-metre (100 ft 2 in) semi-displacement motoryacht designed, inside and out, by Evan K Marshall, with naval architecture by Ed Monk Jr, the same partnership behind most of the yard's larger yachts. BoatTEST's 2015 sea trial described her as a natural progression of the successful 90 Motoryacht, built to give owners the luxuries of a much bigger yacht while still fitting the length restrictions many resort marinas and canals impose.

The model then split into two configurations sold in parallel: an Open Bridge version with an uncovered flybridge entertaining deck, and an enclosed Skylounge version with a true second living room behind the helm. BOAT International's own brokerage reporting counted at least 19 hulls of the Skylounge alone delivered by 2019, while the brokerage tracking service Romeo United Yachts records two Open Bridge hulls specifically, Now We Know (built 2014, delivered 2015) and Iridescence (2019), making the 100 a genuine small production series rather than a one-off design exercise.

Two Upper Decks, One Hull

Both configurations share the same lower and main decks: a single-level main deck runs from the cockpit through a huge aft-deck U-shaped seating and bar area to a country-kitchen galley, then up two steps to a forward dinette, casual helm and day head. The formal dining area seats eight, the salon carries a wet bar and a second day head of its own, and Hunter Douglas electric shades cover the oversized, frameless side windows Ocean Alexander built around aluminum-beam window frames strong enough for open-water use.

Where the decks differ is above. The Open Bridge trades an interior staircase for direct aft-deck access to a fully exposed flybridge with three-across helm seating, a wet bar, table seating for eight and a four-person Jacuzzi, all reached by a fiberglass staircase. The Skylounge instead runs a winding interior staircase to an enclosed deck with its own three-across helm, a smaller dinette, wet bar and day head, giving up open-air deck space for a genuine second living room that stays usable in bad weather. Both versions carry the same 15-foot, 70-horsepower tender on a 2,500-pound hydraulic davit.

Throttle back below 1,250 rpm and the same hull that burns 206 gallons an hour at 23 knots will run over 5,700 nautical miles on a single tank.

What an Independent Sea Trial Found

The tested boat, powered by twin 1,925-horsepower Caterpillar C32 ACERT diesels, reached a top speed of 23 knots at 2,300 rpm burning 206 gallons an hour for a 401-nautical-mile range, and cruised at just under 20 knots at the Caterpillar-recommended 80 percent load, burning 170 gallons an hour for a 485-nautical-mile range. Drop into displacement mode, anywhere below 1,250 rpm, and the range runs into the thousands of nautical miles, up to roughly 5,700 nm at a 7.2-knot idle, the kind of passage-making range that matters more to a 100-footer's owner than outright top speed.

BoatTEST's testers praised the docking manners as much as the open-water ride, bringing the yacht into a slip barely longer than her own hull, with boats fore and aft, using only her 55-horsepower bow and 40-horsepower stern thrusters and 9-square-foot rudders. A pair of 5-foot-3-inch fin stabilizers controlled roll underway, backed by zero-speed stabilization at rest, and in turns the hull leaned only about 5 degrees before the stabilizers brought her level again, a correction the testers called hardly noticeable to anyone not looking for it.

Systems Built for Charter and Long Ocean Passages

The first-generation 100 Motoryacht, tested by BoatTEST in 2015, ran the Caterpillar C32 ACERT pairing exclusively, with no factory alternative offered. Later Skylounge generations moved to MTU power: BoatTEST's 2017 test hull ran twin 1,920-horsepower MTU 12V2000 diesels, and BOAT International's report on the new-build sale of the 2019 hull Hyak confirms the same MTU engines, paired that time with Vector zero-speed fin stabilizers, a different stabilizer brand from the unnamed fins on the earlier CAT-powered test hull. A buyer comparing used hulls should treat the engine generation, not just the model year, as the real dividing line.

Both generations share twin 55-kilowatt Kohler generators, bow and stern thrusters, chilled-water air conditioning, and a hull built from solid fiberglass infusion lamination with high-density structural foam coring and cross-knit carbon fiber reinforcement in high-load areas. Fuel capacity runs 4,000 US gallons (15,141 litres) and fresh water 650 US gallons (2,461 litres) on every hull BoatTEST and Romeo United Yachts have specified. Ocean Alexander's turn-key delivery program, which BoatTEST inspected on its test boat, throws in a full spare-parts kit for both engine brands, a wheel puller, a 10-person life raft and complete china and cookware, useful context for a buyer pricing a used hull against a bare one.

Five Staterooms, a Crew of Five

The full-beam master occupies the width of the boat, with a centerline king berth, his-and-hers heads sharing one shower, a walk-in closet for one side and a hanging locker for the other, and six vertical hull-side windows that BoatTEST singled out for the light and view they bring underway. The forward VIP has been moved back from the very bow, a small but real comfort improvement on most yachts this size, and it gives good walk-around access to a centerline queen berth, its own ensuite head and a cedar-lined hanging locker.

Two further guest staterooms amidships convert their twin berths to queens and mirror each other exactly. Crew quarters sit abaft the engine room, a layout BoatTEST called the best place for them on a boat this size: a captain's cabin with an ensuite queen berth, well suited to a captain-and-chef couple, plus two more cabins sleeping three additional crew who share a second head and their own separate galley and dining area, kept apart from the guest spaces entirely.

Buying a 100 Today

BOAT International's own brokerage reporting put the asking price of a new-build, 2019-delivery 100 Skylounge, the hull later named Hyak, at 12,000,000 US dollars, sold through Alexander Marine USA with an interior by Mary Flores Yacht Design. The model has since been discontinued in favor of Ocean Alexander's newer Revolution Series, so the only way to buy a 100 today is on the brokerage market, through dealers such as Denison Yacht Sales, Romeo United Yachts and MarineMax, rather than direct from the yard.

Current listings bracket a wide range. Denison Yacht Sales was asking 5,250,000 US dollars in 2026 for Now We Know, the 2015 Caterpillar-powered Open Bridge hull, down from an earlier 5,700,000, while Romeo United Yachts lists Iridescence, the 2019 MTU-powered Open Bridge hull, from 8,200,000. Neither Ocean Alexander nor Alexander Marine USA publishes a factory price list for a discontinued model, and no source found in this research quotes an independently verified running-cost figure for the 100 specifically, so a buyer should budget from comparable 100-foot motoryacht operating costs and confirm fuel burn, generator hours and exact engine generation directly with the selling broker before making an offer.

Pour qui: A buyer who wants full-beam, five-stateroom accommodation and genuine ocean-crossing range in a 100-foot hull, is comfortable buying a discontinued model through the brokerage market rather than new, and wants a real choice between an open-air flybridge and an enclosed skylounge.