On-water test results. Real numbers. Every boat.
Performance figures from Fibrafort's published sea trial and independently published reviews for each key competitor. Every figure cited has a named source. Where no independent test exists, we say so.
All published test results — head to head.
Every figure below comes from a published, named source. All Granfort data is from Fibrafort's published sea trial. Where no independent test exists for a competitor, we say so explicitly.
| Performance metric | Granfort 370 GTX | Sea Ray 320 OB | Sea Ray 370 OB | Beneteau GT36 OB | Schaefer 380 | Monterey 385SS |
|---|---|---|---|---|---|---|
| Hull weight (no engines) | 13,613 lb (6,175 kg) | ~14,566 lb | 21,008 lb | 15,901–16,036 lb | 19,675 lb | 16,000 lb |
| Engines tested | 2×400 HP Mercury Verado V10 | 2×350 HP Mercury V10 | 3×300 HP Mercury Verado | 2×350 HP outboard | No test published | 3×300 HP Yamaha F300 |
| Total HP tested | 800 HP | 700 HP | 900 HP | 700 HP | — | 900 HP |
| Top speed (WOT) | 51.1 mph · 7 persons | ~47–49 mph est. | 50.8 mph (BoatTEST) | 41.3 mph (PB Canada) | No test data | 57 mph (Boating Mag) |
| HP per lb of hull | 1 HP : 17.0 lb | 1 HP : 20.8 lb | 1 HP : 23.3 lb | 1 HP : 22.9 lb | — | 1 HP : 17.8 lb |
| 0 to plane | 8.94 seconds | Not published | 5.7 sec (BoatTEST) | Not published | No test data | ~4.5 sec (Boating Mag) |
| 0 to 30 mph | 10.18 seconds | Not published | Not published | Not published | No test data | Not published |
| Best range cruise speed | 33.8 mph @ 4,500 RPM | Not published (OB) | 38.2 mph @ 4,500 RPM | 34 mph @ 5,000 RPM | No test data | 36 mph @ 4,500 RPM |
| Fuel burn at cruise | 35.9 GPH @ 33.8 mph | Not published (OB) | 42.8 GPH @ 38.2 mph | 39 GPH @ 34 mph | No test data | Not published |
| Best autonomy (full tank) | 209 miles @ 4,500 RPM | Not published (OB) | 201 miles (BoatTEST) | 103 nm (Boote-Mag) | No test data | Not published |
| Fuel capacity | 840 L (221.8 gal) | ~158 gal | 200 gal (BoatTEST) | 200 gal | 273 gal | 250 gal |
| Test source | Fibrafort published sea trial · GPS confirmed | AU Coupe OB test 2021 · BoatTEST sterndrive 2019 | BoatTEST.com 2021 | PB Canada · Boote-Mag · Barche a Motore | No independent test (May 2026) | Boating Magazine · boats.com · Lakeland Boating |
Full consumption table — every RPM point. Both load conditions.
From Fibrafort's published sea trial. Fuel consumption via engine instruments. Autonomy calculated at 100% tank capacity (840 L / 221.8 gal). Speed by GPS.
| RPM | MPH | L/h | GPH | Range (mi) | Mode |
|---|---|---|---|---|---|
| 2,000 | 9.1 | 38.1 | 10.1 | 201 | Economy |
| 2,500 | 10.4 | 47.7 | 12.6 | 183 | Slow cruise |
| 3,000 | 12.2 | 68.2 | 18.0 | 150 | Harbour |
| 3,500 | 15.6 | 91.2 | 24.1 | 143 | Pre-plane |
| 4,000 | 19.6 | 120.3 | 31.8 | 137 | Transitioning |
| 4,500 | 33.8 | 135.7 | 35.9 | 209 ⭐ | Best range |
| 5,500 | 43.8 | 220.4 | 58.2 | 167 | Sport cruise |
| 6,410 | 51.1 | 280.0 | 74.0 | 153 | Top speed |
What the data tells you: The Granfort 370 GTX's best range point is 4,500 RPM — 33.8 mph fully on plane at 35.9 GPH, giving 209 miles of range on the 221.8 gal tank. This is the cruise speed where the hull is most efficient per mile covered. At economy speeds (2,000 RPM / 9.1 mph), burn drops to 10.1 GPH but range actually falls to 201 miles due to longer time on the water. For maximum distance, push to 4,500 RPM and stay there.
Source: Fibrafort published sea trial · Mercury Verado V10 400HP · PASSO 19 REVOLUTION propellers · GPS confirmed. Autonomy based on 100% tank (840 L / 221.8 gal). GPH converted from L/h (÷ 3.785).
Every horsepower works harder in a lighter boat.
Hull weights determine how efficiently each HP is used — fuel burn per mile, acceleration onto plane, and how the boat feels at every throttle position. The Granfort 370 GTX hull weighs 13,613 lb — the lightest in this comparison despite being the only boat with a genuine 37-foot cruiser specification.
All weights shown are hull-only or dry weights. Granfort: 13,613 lb (Fibrafort published sea trial). Sea Ray 370: BoatTEST.com. Beneteau: Power Boating Canada / Boote-Magazin. Monterey: published specifications. Schaefer: published data. Sea Ray 320: manufacturer published.
What each test actually recorded — with full source context.
Why Granfort reaches 51 mph on 800 HP while heavier competitors need 900 HP.
Power-to-weight ratio determines how efficiently each horsepower is deployed — and ultimately how efficiently the boat covers distance per dollar of fuel spent.
The Granfort 370 GTX hull weighs 13,613 lb . Against its 800 HP, that is 17.0 lb per HP — the best ratio in this comparison outside the Monterey (which achieves 17.8 lb/HP but is a bowrider, not a cruiser). The Sea Ray 370 OB needs 900 HP on a 21,008 lb hull — 23.3 lb per HP — to reach 50.8 mph, burning 42.8 GPH at cruise. Granfort reaches 51.1 mph on 800 HP burning 35.9 GPH at its best cruise speed.
Granfort 370 GTX
800 HP · 13,613 lb hull. 51.1 mph GPS-confirmed. Best cruise: 33.8 mph at 35.9 GPH giving 209 miles range.
Sea Ray Sundancer 370 OB
900 HP (3×300) · 21,008 lb. BoatTEST confirmed 50.8 mph — similar top speed but requires 100 HP more on a hull 7,395 lb heavier. Cruise burn: 42.8 GPH vs Granfort's 35.9 GPH at comparable cruise.
Beneteau Gran Turismo 36 OB
700 HP (2×350) · 15,901–16,036 lb. Three independent tests recorded 40.3–41.4 mph — 10 mph slower than Granfort with 100 HP less on a ~2,400 lb heavier hull. Now discontinued.
Monterey 385SS (900 HP std)
900 HP (3×300) · 16,000 lb. Boating Magazine recorded 57 mph — faster than Granfort, with 100 HP more. However: classified as a bowrider/super sport, not a sport cruiser. Different primary mission.
Sea Ray Sundancer 320 OB
700 HP (2×350) · ~14,566 lb. Australian Coupe OB test recorded 33-knot cruise. No full WOT test published for the standard open OB version — estimated 47–49 mph.
Schaefer 380
No published performance test available. At 19,675 lb, any twin or triple outboard configuration faces a significant weight-per-HP challenge. BoatTEST listing suggests a future review is planned.
The boat that draws a crowd everywhere it appears.
What tests measure — and what they don't.
Published sea trial data gives you three things reliably: top speed at WOT, time to plane, and fuel burn at specific RPMs. What the test numbers don't capture:
Fuel tank size and range context. The Granfort's 840 L (221.8 gal) tank is one of the largest in this comparison — 200 gal Sea Ray 370, 250 gal Monterey. Combined with the best-range cruise point of 209 miles (7 persons), this gives genuine coastal range without stops.
Long-term fuel economy. At 35.9 GPH cruise vs the Sea Ray 370's 42.8 GPH, the Granfort burns approximately 6.9 fewer gallons per hour at comparable cruise speeds. Over 100 hours of annual use at $5/gal, that is $3,450 in fuel savings per season — before the hull weight advantage compounds further.
The 13.2 GPH figure — clarified. Earlier versions of this page cited 13.2 GPH cruise fuel burn. The factory test confirms this is the figure per engine at low RPM settings. Combined fuel burn at productive cruise speeds (4,500 RPM / 33.8 mph) is 35.9 GPH — a more useful real-world figure. At very low RPM (2,000 / 9.1 mph) combined burn is 10.1 GPH, but this is harbour-speed, not open-water cruising.
What the data tells the buyer. Clearly.
The Granfort 370 GTX's published performance data confirms: 51.1 mph GPS-confirmed, planing in 8.94 seconds, and a best-range cruise of 33.8 mph giving 209 miles on its 221.8 gal tank. The hull weight of 13,613 lb makes it the lightest boat in this comparison despite its 37-foot length.
The Sea Ray 370 OB is the closest performance rival at 50.8 mph (BoatTEST 2021) — but requires 900 HP on a 21,008 lb hull, burning 42.8 GPH at cruise. The Monterey 385SS goes faster (57 mph) on 900 HP but is a bowrider, not a cruiser. The Beneteau GT36 OB — now discontinued — topped out at 41.3 mph across three independent tests. The Schaefer 380 has no published test data to compare.
Granfort 370 GTX: Fibrafort published sea trial · Mercury Verado V10 400HP FOURSTROKE × 2 · PASSO 19 REVOLUTION propellers · GPS speed measurement. Hull weight 13,613 lb. Fuel capacity 221.8 gal (840 L). Deadrise 20°. LOA 36.2 ft (11.03 m). Beam 11.5 ft (3.52 m). Top speed: 51.1 mph @ 6,410 RPM. Planing time: 8.94 seconds. 0–30 mph: 10.18 seconds. Best range: 33.8 mph at 35.9 GPH giving 209 miles on full tank.
Sea Ray Sundancer 320 OB: BoatTEST.com 2019 (sterndrive version). boatsales.com.au 2021 (Coupe OB — twin 350 HP Verado: 33-knot cruise, 133 L/h, 141 nm range on 598 L). Manufacturer published weight ~14,566 lb. Note: no published WOT test for the standard open outboard version — top speed estimated at 47–49 mph.
Sea Ray Sundancer 370 OB: BoatTEST.com full sea trial 2021 — empty weight 21,008 lb, test weight 22,947 lb (70% fuel, 3 crew), triple 300 HP Mercury Verado (900 HP), 50.8 mph WOT @ 5,900 RPM, 5.7s to plane, 38.2 mph best cruise @ 4,500 RPM at 42.8 GPH, 0.9 MPG, 201-mile range.
Beneteau Gran Turismo 36 OB: Power Boating Canada (2×300 HP Mercury — 41.3 mph WOT @ 5,700 RPM, 48 GPH WOT, 34 mph @ 39 GPH cruise, 100 gal, 3 pax). Boote-Magazin Germany (2×350 HP Suzuki — 36 kn top @ 5,650 RPM, 103 nm range). Barche a Motore Italy (2×350 HP Suzuki — 35 kn top, 199 L/h WOT, 120 L/h @ 24.5 kn). Boating Magazine (spec — 15,901 lb, 17° deadrise, 200 gal, 700 HP max). Production status: discontinued.
Schaefer 380: No published independent performance test as of May 2026. All figures from Schaefer published specifications only. BoatTEST.com has the 380 listed for future review. Displacement 19,675 lb, 273 gal fuel capacity, 18° deadrise.
Monterey 385SS / 385SE: Boating Magazine (385SE — triple Yamaha F300 300 HP / 900 HP total — 57 mph WOT, ~4.5s to plane, 37'0" LOA, 16,000 lb, 250 gal, 21° deadrise). boats.com review 2024 (50+ mph, deep-V chop handling). Lakeland Boating (385SE — triple Mercury Verado 300 HP — 36 mph @ 4,500 RPM cruise). Category: bowrider/super sport — not a sport cruiser.
