One boat model – three engine options. With special thanks to the Tristram Marine Team - who supplied us with three Tristram 821 Offshore models, each powered by a different propulsion option - we were able to get out on Auckland Harbour and report on a showdown between the MerCruiser 270hp 3.0L V6 Diesel Sterndrive, the Twin Mercury 250hp V8 Verado outboards, and the Single Yamaha 450hp V8 XTO outboard. Each setup offers distinct advantages, particularly in fuel efficiency, maintenance, and performance. After a day on Auckland Harbour, we discovered how these three compared against each other.
MERCRUISER 270HP 3.0L V6 STERNDRIVE DIESEL
Single 3.0L V6 diesel engine Sterndrive configuration.
The MerCruiser 3.0L V6 Sterndrive Diesel engine is designed
to balance power, efficiency, and reliability. This compact yet powerful V6 diesel engine delivers 270 horsepower and offers smooth cruising performance while maintaining fuel efficiency.
One of the standout features of this engine is its modern common-rail direct fuel injection system, which optimises fuel delivery for improved efficiency, lower emissions, and reduced operating costs. Combined with a turbocharged and aftercooled design, the engine ensures strong torque output across a broad RPM range, making it well-suited for leisure and commercial vessels.
The MerCruiser 3.0L V6 has improved engineering for quieter and refined operation on previous models, featuring advanced sound- dampening technologies that minimise noise and vibration. Its closed-loop cooling system enhances durability by preventing exposure to corrosive seawater, extending engine life and reducing maintenance requirements.
Power: 270 hp
Configuration: Single sterndrive diesel
Fuel Efficiency: Diesel engines typically excel in fuel efficiency, especially at mid-range RPMs, which is ideal for long-distance cruising.
Weight: Generally heavier than the outboard options, but the weight is centrally located, sometimes assisting stability.
Maintenance: Diesel engines are generally longer-lasting but require more intensive servicing.
Performance: Excellent low-end torque, making it ideal for heavy loads and rougher waters. However, it does lack the top-end speed of single and dual outboard configurations.
Ideal For: Offering torque for heavy loads, prioritising fuel economy when travelling to distance fishing grounds and then trolling for many hours. Most of the Tristram Diesel sterndrives sold to date have been for fishing, where trolling fuel burn is an important consideration. From these figures, we can see an excellent range at low speeds; at a trolling speed of about 8.6 knots, the sterndrive can cover 499 nautical miles using less than one litre of diesel per nautical mile.
The MerCruiser sterndrive option also offers a clean transom and can be better suited for some hull designs.
TWIN MERCURY 250HP V8 VERADO OUTBOARDS
Two 4.6L V8 petrol engines Outboard configuration
he Mercury 250hp V8 Verado outboard engine is designed to balance power, efficiency, and smooth operation. Built around
a 4.6L V8 powerhead, it provides strong acceleration and exceptional mid-range performance while maintaining the quiet, refined operation that the Verado range is known for.
One of the 250hp Verado’s standout features is its Advanced MidSection (AMS), which significantly reduces vibration and noise, ensuring a smoother and more comfortable ride. This makes it an excellent choice for boaters, as it provides a quiet and refined experience without sacrificing power.
The twin outboard 821 Offshore option can be spec’d with electric joystick steering. This feature will allow for ease of manoeuvring into jetties. The joystick also features a spot lock option that will hold the vessel on the spot for deep drop fishing, adding to convenience and safety.
Designed for both performance and reliability, the 250hp Verado features dual overhead camshafts (DOHC) for increased efficiency and durability. It also boasts a lightweight design, ensuring an optimal power-to-weight ratio for improved fuel efficiency and top-end speed.
Whether used for offshore adventures, cruising, or fishing, the Mercury 250hp V8 Verado is a versatile, well-rounded outboard that offers a seamless blend of power, comfort, and innovation.
Power: 500 hp (combined)
Configuration: Twin outboards
Fuel Efficiency: Outboards are less fuel-efficient than diesel sterndrives, but advancements in Mercury Verado engines offer improved fuel economy.
Weight: This setup adds more weight to the stern, but it provides redundancy if one engine fails.
Maintenance: Outboards are easier to maintain than sterndrives, with more straightforward access and fewer components below deck.
Performance: The twin Verado setup offers high top-end speed and excellent handling, especially for sport-oriented boating and fast acceleration out of the hole.
Ideal For: Performance-oriented boaters prioritising speed, easier maintenance and redundancy should you run into trouble.
SINGLE YAMAHA 450HP V8 XTO OUTBOARD
One 5.6L V8 petrol engine Outboard configuration
Yamaha has introduced the XTO Offshore 450, an evolution of its flagship XTO 425, delivering enhanced performance and modern convenience. Retaining the robust 5.6L big block displacement and many features of its predecessor, the XTO 450 builds on an already impressive platform.
The Phase Angle Control Charging System is a key upgrade, providing three-phase, simultaneous charging that generates more net amps at low RPM. This is ideal for powering high-demand devices like gyro stabilisers and air conditioning systems.
Yamaha’s TotalTiltTM system adds to the engine’s usability, allowing faster and easier tilting with a simple double-press of the tilt button. Meanwhile, the cowling now features raised chrome graphics and refined panels, giving the engine a sleek, premium aesthetic.
Yamaha has introduced new propellers for different vessel types, including the XTO EC® Prop for heavy boats and a 27-inch pitch prop for lighter vessels seeking higher speeds.
The Yamaha 450hp engine can be optioned with the all-new Yamaha Helm Master. This new option features a single engine joystick, allowing for maintaining a position for fishing or even integrating into a bow thruster for ease of docking. The next Tristram 821 Offshore single engine currently in build has the Yamaha Helm Master/Bow thruster integration fitted.
The XTO Offshore 450 is the premium choice in Yamaha’s outboard line-up.
Power: 450 hp
Configuration: Single outboard
Fuel Efficiency: More fuel efficient at lower speeds than the twin outboard option and performs well at cruising speeds.
Weight: The single-engine setup is lighter than the Diesel Sterndrive and twin outboard configurations, allowing for less stern-heavy weight distribution.
Maintenance: Outboards are generally easy to maintain, and the Yamaha XTO is known for its reliability.
Performance: The high-power single outboard option was the lightest power option with great top-end speed of 48 knots.
Ideal For: Those looking for high speed in a lighter, more straightforward setup. Providing high power in a single unit can be preferable for some boat designs with a more straightforward, single- engine setup. The single-engine boarding platform on the Tristram 821 Offshore matched with the Yamaha 450hp is unique with large swim/ fishing platforms on either side of the engine. This added real estate makes for a generous area for many activities.
THE NUMBERS, KEY FEATURES & PERFORMANCE CHARACTERISTICS:
Power Output
MerCruiser: 270hp (single engine)
Mercury: 500hp total (250hp x 2)
Yamaha: 450hp (single engine)
The twin Mercury setup offers the highest total horsepower, followed by the Yamaha, then the MerCruiser.
Fuel Type
• MerCruiser: Diesel fuel
• Mercury Verado: Petrol 87 Octane • Yamaha XTO: Petrol 95-98 Octane
Fuel Efficiency
The MerCruiser diesel engine offers the best fuel efficiency, especially at cruising speeds.
Mercury Verado outboards are designed for efficiency, with features like Advanced Range Optimization (ARO)
The larger displacement Yamaha 450hp V8 XTO outboard offers a balance of high performance and fuel efficiency, particularly when operated at moderate cruising speeds.
Noise and Vibration
- The Mercury Verado outboards feature an Advanced MidSection (AMS) that isolates vibration and reduces noise. This technology, combined with their V8 configuration, makes them exceptionally quiet; there also has to be something said of any twin-rigged boat; the harmonics offer something just a little pleasing to the ear.
- The diesel MerCruiser, which was reasonably quiet at idle, was undoubtedly noisier than the outboard options, particularly at lower speeds when getting up on the plane. However, once at cruising speed, the diesel noise level aligned more closely with that of the outboard options. Today’s MerCruiser diesel engine has advanced significantly from the often nicknamed ‘coal burner’ diesel of the past, showing improvements in both exhaust noise and emissions.
- Yamaha has used their Advanced Mounting System on the 450hp V8 XTO outboard; these are upgraded engine mounts and an improved exhaust routing to minimise vibrations. The engine felt smooth through the rev range, particularly at cruising speeds.
Boat and Engine Weight (at time of testing):
MerCruiser 270hp 3.0L V6 Diesel Sterndrive: 2.917 Ton
Twin Mercury 250hp V8 Verado outboards (combined): 2.986 Ton
Single Yamaha 450hp V8 XTO outboard: 2.900 Ton
Engine Weight Only:
MerCruiser 270hp 3.0L V6 Diesel Sterndrive: 475 Kgs
Twin Mercury 250hp V8 Verado outboards (combined): 544 Kgs
Single Yamaha 450hp V8 XTO outboard: 458 Kgs
Maintenance and Serviceability
Mercury Verado outboards offer easy maintenance with features like an easy-access door for oil checks.
Again, the Yamaha Outboard configuration allows easier access and servicing.
The MerCruiser sterndrive requires more complex maintenance due to its inboard nature.
Pricing:
Pricing varies with currency and exchange rate fluctuations and how engine manufacturers package the engines with different gauges, propellers, and associated electronics. There are also varying boat build expenses and price differences between outboard and stern drive options. There was a $25,000 difference between the most and least expensive options at the time of printing (the highest being the twin outboard and least expensive being the diesel package). This price difference of $25,000 would be less of a consideration than selecting the right engine type for the intended boating activity or boat ramp depth available.
Typical Annual Servicing costs (PC Sum):
MerCruiser 270hp 3.0L V6 Diesel Sterndrive: approx. $1,800
Twin Mercury 250hp V8 Verado outboards: approx. $2,300
Single Yamaha 450hp V8 XTO outboard: approx. $1,300
CONCLUSION – HORSES FOR COURSES…
What is weighted as a priority to one power boatie may differ from another – fuel burn versus performance is always a significant consideration. The fuel results from our day out were largely as expected: the sterndrive offered the best fuel economy, while the outboard options were less efficient – especially when factoring
in the higher cost of petrol compared to diesel. However, as mentioned, it’s not always about fuel consumption; for some, performance, which the outboard options deliver, takes priority over economy.
With all the weights, fuel consumption, and performance figures considered, your choice between these setups ultimately depends on your boating requirements – whether it’s high-speed performance with the Mercury Verado twins, long-distance reliability and economy with the MerCruiser diesel, or a powerful, straightforward Yamaha XTO outboard.
One constant is that the more horsepower you have and the more you use it, the more fuel you will burn.
The final decision depends not only on which engine style best suits your hull design, as both outboard and sterndrive setups have their advantages, but also on the type of boating activity that fuels your passion. Boat ramp depths can also be a contributing factor to a purchase decision. The sterndrive will draw more than the outboard. Therefore, an outboard option could be a wise decision on shallow boat ramps. Whether it’s offshore fishing, cruising with a focus on economy, or high-speed water sports, this will determine the ideal power choice for your boating lifestyle.
THE SHOOTOUT VEHICLE: THE TRISTRAM 821 OFFSHORE
A special thank you to the Tristram Marine Team, who helped make this article possible. The supply of three Tristram 821 Offshore models, each equipped with a different propulsion option, is greatly appreciated – we went out looking for a typical hard top model to be the donor boat to allow us to complete this task – in saying that – there is certainly nothing average about the Tristram 821 Offshore, far from it in fact.
The Tristram 821 Offshore, conceived in 2020, was an entirely new design for the company that took two years to deliver the finished product. Unlike some manufacturers that modify an existing model, the 821 was designed by Tristram Marine, using Computer Aided Design (CAD) with foam plugs made for the hull, deck, superstructure and all the various moulds. The CAD system’s accuracies are within 0.0025mm.
The Tristram 821 Offshore is more than a magnificent boat for entertaining; it is designed primarily to go serious fishing. However, you don’t have to have built- in tuna tubes, game poles, electric reel connections, or tackle drawers, as the 821 is available with a more family cruiser-based layout.
The 821 is available in twin or single outboards up to 600hp or diesel sterndrive. When you offer two power types, outboard and sterndrive, there will be some variances in the transom design. The usual method is two different transom moulds. However, not so Tristram Marine. Tristram has two deck moulds. So you don’t see any joining lines between the transom moulding and the coamings.
The 821 hull has extra wide downturned chines, with a 21deg vee at the transom. Thanks to a deep keel, the boat tracks perfectly and goes precisely where you point it. It holds its bow up nicely in a steep following sea, and you don’t have any wavering or issues with broaching. Trim tabs are built into the hull, so there is no obtrusion off the transom. The 2.78m beam offers generous space within and outstanding stability, which we experienced on our day out on the water.
Speaking with Kingsley Fink, General Manager of Tristram Marine, 57 Tristram 821 Offshore boats have been produced to date, with 70% of these featuring the diesel sterndrive configuration, typically chosen by game fishermen and families who venture far offshore. However, the twin outboard option is also becoming popular among owners who appreciate the security of having a backup engine in case of unforeseen circumstances.
Additionally, there has been a growing preference for the extra deck space that a sterndrive offers around the transom, but with slightly enhanced performance. This is where Tristram Marine collaborated closely with Yamaha and now offers a single Yamaha outboard option. Other available single outboard options include the Yamaha 450 four-stroke V8 outboard and the 600hp Mercury V12.
The Tristram 821 Offshore is built from an impeccable heritage and puts a new perspective on trailer boat luxury.
Tristram 821 Offshore
• Design Name: Tristram 821 Offshore
• Year Launched: 2022
• Builder: Tristram Marine
• Designer: Tristram Marine
• LOA: 8.77m
• Beam: 2.78m
• Deadrise: 21 degrees
• Trailerable Weight: 3500kg
