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Start With Crew Size, Not Boat Size
Every marine grill listing leads with square inches, and almost nobody explains what the number means in food.
The working figure is 30-40 square inches of grate per person for a normal meal — a burger and something alongside it. Push to 50 square inches per person if you cook thick steaks or whole fillets that cannot be stacked.
Run the arithmetic against the common sizes:
100-120 sq in — two people comfortably, three in batches.
160-165 sq in — the most common marine size. Four people in one load, six in two.
200+ sq in — six or more, or a crew that eats in shifts without the cook waiting.
Boat length is a proxy for crew size, not a spec in itself. A 32-foot sailboat crewed by a couple needs a smaller grill than a 24-foot center console that carries six anglers.
Pro Tip: Count the maximum number of people you have fed aboard in the last two seasons, not the number of berths. Berths overestimate almost every boat.
Why BTU Numbers Mislead on the Water
Ashore, BTUs are a rough proxy for how hard a grill can sear. On a boat that relationship breaks down, because wind steals heat faster than the burner adds it.
A 9,000 BTU marine grill at anchor in a sheltered cove behaves like a 9,000 BTU grill. The same grill at 12 knots of apparent wind behaves like something far weaker — the flame is still burning, but convective loss carries most of it past the food.
This is why infrared marine grills win in open water at nominally similar output. The burner heats a radiant plate, the plate cooks the food, and wind removes heat from a hot steel plate far more slowly than it removes heat from a bare flame. A 12,000 BTU infrared grill and a 12,000 BTU open-burner grill are not comparable appliances outdoors on the water.
What to take from that: if you grill at anchor in protected water, judge on BTUs and grate size. If you grill in open water or off a moving boat, prioritise the burner design over the BTU figure entirely.
Pro Tip: Ask where you actually cook. Sheltered anchorage grilling and open-roadstead grilling are different problems and they buy different grills.
Sizing by Boat Type
Small day boats and RIBs (under 20 ft): a compact 100-120 sq in gas grill on a rod holder mount. Anything larger is a stowage problem and a weight problem on a light hull.
Center consoles and runabouts (20-28 ft): 160 sq in is the sweet spot. Rod holder mounting is usually the strongest option because the holders are already through-bolted into reinforced structure. See the [mounting hardware guide](/guide/boat-grill-mounting-hardware-guide) for the measurements to take first.
Cruising sailboats (28-40 ft): 160 sq in with a levelling stern-rail mount. Prioritise a sealed lid if you want to roast at anchor rather than just grill.
Larger power boats and liveaboards (35 ft+): 160-200+ sq in with infrared or a heavy lid, and a permanent deck mount rather than something you lift on and off.
Pontoons and dock setups: capacity is cheap because weight and stowage are not constrained the way they are on a sailboat. Size up. The [pontoon and dock grilling guide](/guide/pontoon-dock-grilling-guide) covers the mounting differences.
Weight, Stowage and the Numbers Nobody Lists
Grate size sells the grill. Three other numbers decide whether you enjoy owning it.
Stowed dimensions — the grill has to fit a locker with fenders, lines and a boat hook already in it. A grill with fold-away legs and a flatter body stows far better than a domed kettle of the same capacity.
Mounted weight — grill plus a full 1 lb canister plus food is typically 30-45 lbs hanging off a rail. Check the mount is rated for that total, not just the grill's dry weight, and check the stanchion or fence member behind it is properly backed.
Lift weight — if you take the grill off the mount at the end of every trip, a 22 lb grill and a 28 lb grill feel very different at the top of a companionway ladder.
Canister burn time — a 1 lb propane canister gives roughly 1.5-2 hours at full output on a single-burner marine grill. Two canisters aboard is the sensible minimum for a weekend.
Matching Grills to the Sizes Above
Two people, sheltered water, small boat: the [Kuuma Stow N Go 160](/review/kuuma-stow-n-go-160-marine-gas-grill) on fresh water, or the [Magma Cabo](/review/magma-marine-cabo-gas-grill) if the boat lives on salt.
Four people, mixed conditions: the Cabo remains the default, and the [Cabo vs Kuuma comparison](/compare/magma-cabo-vs-kuuma-stow-n-go-160) explains where the price difference goes.
Four or more, open water and wind: the [Magma Catalina 2](/review/magma-catalina-2-infrared-marine-grill) and its infrared plate. The [Cabo vs Catalina 2 comparison](/compare/magma-cabo-vs-catalina-2) is the decision in detail.
Lid-down cooking and whole fish: the ChefsMate's kettle body — see [ChefsMate vs Cabo](/compare/magma-chefsmate-vs-cabo).
Liveaboards who roast and bake aboard: the Dickinson, covered in [Sea-B-Que vs Catalina 2](/compare/dickinson-sea-b-que-vs-magma-catalina-2).
The full field is ranked in the [best boat grills roundup](/best-of/best-boat-grills).
Common Sizing Mistakes
Buying for the biggest party you have ever hosted. You will cook for two or four almost every time. Size for the normal meal and accept batching on the rare big night — an oversized grill costs you locker space fifty weekends a year.
Ignoring the mount in the budget. Marine grills ship without mounts. Add $60-$160 before you compare prices between brands, and buy the mount from the grill's manufacturer.
Buying 304 stainless for salt water. The alloy matters more than the size. A perfectly sized grill that is pitting after one season is the wrong grill — the [marine grill maintenance guide](/guide/marine-grill-maintenance-guide) covers why 316 is specified.
Assuming higher BTUs fix wind. They do not. Burner design fixes wind.
Pro Tip: If you are between two sizes and the boat is small, take the smaller grill and the better mount. Stowage frustration outlasts capacity envy.
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