Expert Review, Technical Specifications & Market Analysis
| Feature | Specifications |
|---|---|
| Overall Length | 41' 4" |
| Beam | 13' 6" |
| Draft | 30" |
| Displacement | 22,400 lbs |
| Engines | Standard: Quad Mercury 300 V8 Verado (1,200 HP min); Optional: Quad 400 V10, Triple 600 V12 (max 1,800 HP) |
| Fuel Capacity | 620 gallons (main) plus 38 gallons (diesel generator) |
| Water Capacity | 90 gallons |
| Cabins / Heads | Private master stateroom plus mid-berth for 3 (premium innerspring mattresses); 1 enclosed head with separate shower and rain showerhead (30-gal waste capacity) |
| Max Speed | 61.5 mph (WOT with Triple Mercury 600 V12) |
| Cruise Speed | Approx. 36.0 mph @ 4,000 RPM (with Triple Mercury 600 V12 Verado) |
Source: Spec & Photos courtesy of Boston Whaler. Specs verified by Tony Smith, USCG 100 Ton Master, on August 10, 2026.
Part of the Boston Whaler Conquest series — see how owners step up through the lineup.
The 405 Conquest is the most versatile boat in the 40-foot class, but versatility comes with trade-offs. The cabin is functional, not luxurious. The cockpit is spacious, but not as fishing-focused as a true center console. Boston Whaler built this boat for the owner who wants 80% of a fishing boat and 80% of a cruiser, not 100% of either. The build quality is excellent. The unsinkable foam-core construction is proven. The Mercury integration is seamless. If you're buying this boat, spec the triple 600 Verados and the Fathom e-Power system. The performance and efficiency gains justify the cost.
This boat is for the owner-operator who runs 40 to 60 days per year and values simplicity over status. It's not for the buyer who wants a flybridge, a full galley, or a dedicated crew. It's not for the tournament fisherman who needs a 50-gallon livewell and rocket launchers. It's for the business owner who wants to fish the Bahamas on Thursday and host clients on Saturday without hiring a captain or switching boats. If that's you, this is the right boat.
Resale is strong. Boston Whalers hold value better than most production boats in this class. Expect to retain 60% to 70% of your purchase price after five years with proper maintenance. Annual operating costs run $60,000 to $80,000 for 50 days of use. Fuel is the biggest variable. Budget $600 per 100-mile trip with the triple 600 setup. Insurance runs $12,000 to $15,000 per year in South Florida. Maintenance is straightforward. No inboard engines, no generators to service, no complex systems. This is a boat you can own and operate without a full-time crew.
Video courtesy of Boston Whaler.
Photos courtesy of Boston Whaler.
The 405 Conquest is Boston Whaler's flagship cabin cruiser: 41 feet 4 inches long, 13 feet 6 inches of beam, with a private master stateroom, a mid-berth sleeping three, and an enclosed head with a separate shower. It carries 620 gallons of fuel and 90 gallons of water, takes up to 20 people, and rates from 1,200 to 1,800 horsepower.
Deadrise at the transom is 19 degrees, dry weight is 22,400 pounds, and loaded weight is 30,360 pounds. This is the model for an owner who wants a real cruising interior without giving up outboard simplicity or the ability to fish. If the accommodation is not the point for you, the 420 Outrage puts a similar hull size into an open center console.
620 gallons of fuel, plus a separate 38-gallon diesel tank for the generator. Water is 90 gallons and the waste tank holds 30 — and 620 gallons alongside a documented 36.0 mph cruise covers serious ground.
The generator tank is the detail worth noticing. Running the genset on its own diesel supply keeps it off your main tanks, which means air conditioning at anchor does not eat into the fuel you need to get home. That is cruising-boat logic rather than fishing-boat logic. For contrast, the 420 Outrage carries 700 gallons of fuel but only 60 gallons of water.
The 405 Conquest has a private master stateroom plus a mid-berth for three, and an enclosed head with a separate shower. Water capacity is 90 gallons, the largest in the current range, and the waste tank holds 30 gallons. That combination is what makes multi-night trips practical rather than theoretical.
A separate shower stall rather than a wet head is the detail that changes a week aboard, and so is the water. The 420 Outrage carries 60 gallons and the 380 Realm 55. Day capacity is 20 people, the highest Boston Whaler rates in the current line, so the boat entertains as easily as it cruises. Loaded it weighs 30,360 pounds against 22,400 pounds dry.
With triple Mercury 600 V12s the 405 Conquest has been recorded at 61.5 mph, with a cruise of 36.0 mph at 4,000 RPM. Treat both as engine-package results rather than factory claims.
Those are serious numbers for a 41-foot cabin boat weighing 30,360 pounds loaded, and the V12s are the reason. Torque low in the rev range is what lifts a heavy hull onto plane and keeps a cruise speed honest with fuel, water and people aboard. The rating runs 1,200 to 1,800 horsepower, so triple 600s sit near the top of it. For most owners the 36.0 mph cruise is the number that matters, because it turns a long coastal run into an afternoon.
The 405 Conquest is the bigger, more capable cruising boat; the 380 Realm is the tighter, lighter one. The 405 is 41 feet 4 inches by 13 feet 6 inches with a private master stateroom, a mid-berth for three, a separate shower, 620 gallons of fuel and 90 gallons of water. The Realm is 38 feet by 11 feet 8 inches with one cabin, one head, 445 gallons and 55.
Draft is close, 29 inches against 30, but weight is not: 17,000 pounds dry against 22,400. Capacity goes from 16 people to 20. Both run outboards and both rate to a high ceiling, 1,700 horsepower on the Realm and 1,800 on the Conquest. If your cruising is a couple plus occasional company, the Realm is enough boat. If it is a family staying aboard for a week, the Conquest is the one.
Boston Whaler rates the 405 Conquest from 1,200 to 1,800 horsepower, the same band as the 420 Outrage and the highest in the current line. That means triple or quad outboards. Triple 600 V12s have been recorded at 61.5 mph with a 36.0 mph cruise at 4,000 RPM.
The boat needs it. Dry weight is 22,400 pounds and 30,360 pounds loaded with engines, fuel, water and gear, making this the heaviest model Boston Whaler currently builds. Beyond speed, the argument for the larger packages is redundancy: on a cruising boat carrying family rather than crew, getting home on the remaining engines is worth more than any top-end figure. Deadrise at the transom is 19 degrees.
