Grady White Marlin 300, the 30-Foot Walkaround Explained

Grady White Marlin 300, the longest-running name in the lineup

The Grady White Marlin 300 is a 30-foot 6-inch walkaround cabin boat with a 10-foot 7-inch beam, twin Yamaha outboards and room to sleep four. It is also the oldest continuous thread in Grady-White's range. Grady-White's own history credits the Marlin 28 of 1989 with introducing the SeaV2 hull, and the company describes the Marlin 300 as the first model built on that hull, continuously refined for more than three decades.

The buyer is an offshore angler who wants a closed foredeck and a dry cabin rather than an open center console. BoatTEST called it a welcome alternative to any center console because the protected bridge and closed bow make long runs drier and safer, while the cockpit still has more square footage behind the helm than most center consoles of its size.

From Marlin 28 to Marlin 300, a lineage in catalogs

Grady-White's archived brochures trace the evolution. The 1990 catalog shows the Marlin 28. By 1995 the 30-foot walkaround cabin was called the Marlin 30, and the 2000 catalog lists it as the Marlin 300. Power & Motoryacht's 2004 test describes the model as being in the lineup since 1989, treating the line as one continuous boat.

The big modern step came with the 2004 redesign, which Grady-White based on owner surveys and boat show forums and on lessons from the Express 330. The anchor began deploying through the center of the integral pulpit instead of off a roller at its tip, hardware moved to 316 stainless, the helm gained a flush-mount electronics kit, the companionway door became a slide-away design, and the cabin got a teak and holly sole, a teak table and more galley counter space. Aft, a fold-down transom seat replaced the fixed seat and a transom fish box borrowed from the 330 was added.

Since then, changes have been incremental: four-stroke engines growing from twin 225s to twin 350s, a side boarding door, Helm Master EX digital steering standard, Captain Grady app support and a composite stringer system listed as water-impervious.

What the SeaV2 hull does on this boat

Power & Motoryacht explained the SeaV2 principle using the Marlin: a running surface where no two places share the same deadrise, about 20 degrees at the transom and 30 degrees amidships at the time, with a sharp entry, strakes and chines that knock spray down and wedge-shaped sections that add buoyancy as the bow rises over a wave. The current specification lists 19.5 degrees at the transom.

Sport Fishing's tester ran the redesigned boat out of North Carolina's Beaufort Inlet into 4 to 6-foot seas at about 25 mph without drama and noted that the cabin's weight sits farther forward than on the center console sharing the hull, so the Marlin runs flatter. The same writer was clear-eyed: the 300 is a stable, roomy boat that handles head seas well, not a narrow offshore racer that flies through them.

A cabin for four with a proper head

Three fiberglass steps lead down to a teak and holly sole. To port is the galley with a stainless sink, Corian counter, refrigerator, microwave and an electric glass-top stove. To starboard is an enclosed head with sink, shower and a VacuFlush toilet with a 10-gallon holding tank. Forward, a V-berth with a cherry table converts into a double, and a second double berth sits amidships under the bridge deck, with netted storage and overhead rod racks.

Systems are generous for a 30-footer: a 6-gallon water heater, 32 gallons of fresh water, dockside power with galvanic isolator, four batteries with a charger and a hot and cold cockpit shower. The options list adds an 8,000 BTU cabin air conditioner, a 5 kW diesel generator with its own 12-gallon tank, a bow thruster and a 19-inch TV. Power & Motoryacht noted one drawback of the generator in 2004, exhaust residue on the port quarter, and the need to carry diesel separately.

A cockpit set up for canyon trolling

The Marlin is built to fish far offshore, and the cockpit equipment reflects that.

• 290-quart insulated, lighted transom fish box with overboard drain
• 32-gallon port livewell with light, full-column inlet and an 1,100 gph pump
• Starboard rigging station with freshwater sink, insulated bait box and lockable drawers
• Fighting chair reinforcement in the cockpit sole
• Four gunwale rod holders, six hardtop rod holders, four side-mounted holders and rod racks under each gunwale
• Hardtop with radio box, spreader lights, outrigger plates and full curtains; 18-foot crank outriggers optional
• Fold-down transom bench with levered seacocks below, a feature BoatTEST praised
• Port cockpit side door with boarding ladder plus a transom door

Twin F300 versus twin F350, measured

Grady-White tested the Marlin with twin F300s in 2010 at 11,697 pounds loaded: 49.5 mph at 5,800 rpm and a 29.7 mph optimum cruise on 21.5 gph, or 1.38 mpg. The 2024 test with twin 4.3-liter F350s at 11,411 pounds recorded 54.9 mph at 6,000 rpm and an optimum cruise of 29.6 mph at 3,500 rpm on just 17.6 gph, or 1.68 mpg.

The newer engines are both faster and noticeably more efficient at cruise. With 282 gallons in two 141-gallon tanks and a 10 percent reserve, the F350s give roughly 425 statute miles at that cruise. BoatTEST's own run with twin F300s reported about 390 statute miles at 27.6 mph. Either way, the Marlin has the legs for canyon runs with plenty in reserve.

An era guide for used Marlin 300 shoppers

Pre-2004 Marlins and Marlin 30s are inexpensive older boats that need careful surveys and, often, a repower. Boats from the 2004 redesign onward have the modern cabin, pulpit and transom; Power & Motoryacht noted that their stringers were marine plywood encapsulated in woven fabric and closed-cell foam, with end-grain balsa coring above the waterline, so moisture readings matter. Later boats list composite stringers and transom and run on more efficient Yamaha four-strokes.

Expect annual costs of $18,000 to $35,000 for a boat kept in a slip, including twin-engine and generator service, bottom paint, insurance, dockage and fuel. Owners on Grady-White's review page include buyers on their third Grady and families who moved up from a Gulfstream 232 after two seasons, which says plenty about loyalty to this model.