Review: Mercury 115 Pro XS outboard motor

By: Tim Van Duyl, Photography by: Nathan Jacobs

Presented by
  • Trade-A-Boat

The new four stroke Mercury 115 Pro XS offers more revs, a new intake, and has a reprogrammed ECU. It’s a very serious contender for performance and economy.

The Mercury 115 Pro XS is the latest in a highly successful series of Mercury FourStroke outboard motors. At 115hp it is the highest horsepower version of the 2065cc, single-overhead cam (SOHC), inline four-cylinder range that’s available from 75hp. It sits in a competitive section of the market, with direct competition from the Yamaha V MAX SHO 115. But while it’s rated at 115hp – like the non-Pro XS 115hp model from the same family – the Mercury Pro XS outboard is rumoured to have closer to 125 horsepower thanks to a raised rev limit (up from 6000rpm to 6300), change of intake and reprogrammed ECU.

 

115hp Mercury Pro XS

Mercury 115hp Pro XS four-stroke outboard motor

Our review engine featured the optional Command Thrust leg featuring a higher ratio 2.38:1 gearbox (standard ratio is 2.07:1) allowing the use of bigger propellers. Mercury Command Thrust legs feature a larger torpedo that makes steering more direct, a positive for ocean travellers. The engine was fitted with Mercury’s own stainless steel three-blade Enertia prop at 14.3in with 18 degrees of pitch.

This series of Mercury FourStroke engines are low tech – compared with the competition they give away eight valves in the powerhead and don’t feature variable cams or valve-timing abilities. But this saves weight, making the Mercury 115hp Pro XS the lightest outboard in its class despite a relatively large capacity at 2065cc. Its direct rival, the Yamaha V-MAX SHO, is 1832cc.

Our test boat for the day was an Anglapro 514 Sniper Pro, an all-aluminium side console made in Australia and aimed at the fishing boat market. The hull weighs 570kg (dry), is 5.15m long and has a 2.25m beam. It’s a pressed hull, featuring strakes and a shallow deadrise.

Although not rated for as much as 115hp, Anglapro dealer Brisbane Marine Centre chose to fit the Mercury 115 Pro XS to its demonstrator boat and it wanted the excitement. From our review, I’d say the hull felt more than capable of taking the higher horsepower.

 

How does the 115 four stroke Pro XS perform?

Mercury 115hp fuel economy figures

At only 165kg for the Command Thrust model – 163kg for the standard leg in 20in length – it undercuts the Yamaha V-MAX SHO 115 by at least 5kg.

Holeshot is excellent. The combination of the higher ratio Command Thrust gearbox and stainless steel propeller push the lightweight Anglapro onto the plane quickly and smoothly. At wide open throttle (WOT), the 115 and Enertia prop were matched perfectly to the hull’s weight and load – we saw 6200rpm, just 100rpm short of the engine’s electronically controlled 6300rpm limit. At WOT we enjoyed 38kt – more than enough to blow the hair back on the little side console. Power delivery was punchy right up to 5500rpm and quick jabs on the throttle were matched by a fast response from the engine, and quick acceleration.

At idle the engine is quiet. In gear it moved steadily and fairly fast at 2kts thanks to that big 14.2-inch propeller. Although the Anglapro 514 is more of a bait and lure flicking boat, owners could reasonably expect to take one gamefishing on the right day. At 6kt you could expect to cover more than 80 nautical miles or 150km courtesy of the 6.6 litres per hour fuel burn at 2000rpm.

 

Economy

Testing for economy, we found optimal cruise at 3500rpm which delivered 18kt and only 12.2L/h fuel burn. That’s great economy and would have the hull covering up to 134 nautical miles or almost 250km, keeping 10 per cent fuel in reserve. Interestingly, pushing the engine up to 4000 and even 4500rpm didn’t impact overall economy much, while it felt equally smooth on our test day. It felt willing between 3500 and 4500rpm – handy if conditions aren’t ideal and you can’t hold a higher cruise or equally if you’re in a bit of a hurry and can.

 

Noise and vibrations

Noise was never an issue with the combination, quite the opposite, the 115 Pro XS was quiet at high rpm with a deep grunty sound as revs built at WOT. We have tested the non-Pro XS 115hp model and it was equally quiet but we thought the Pro XS was sounded throatier – perhaps down to the revised intake. Engaging forward or reverse was never harsh and the engine never shook or vibrated more than expected.

The 115hp Mercury Pro XS shares its cowling design with the standard 115hp model and looks modern and smart in traditional Mercury black with red decals. The Pro XS can be distinguished by racy graphics not seen on the standard models.

 

 

Emissions

While the regular Mercury engines meet three-star emission targets set by the OEDA, the Pro XS has not yet been rated – at the time of publication, we don’t know whether the engine hasn’t been through testing or the more aggressive tuning doesn’t comply. When we know, we’ll update the report. But like all modern four-strokes, the engine was fume-free once up to temperature and with its through-prop exhaust, there was no smoke to be seen.

 

Steering

The Mercury 115 Pro XS still uses cable throttles, like all competitors in its class. No doubt the day will come when electronic controls make their way into smaller engines but for now, bigger and more bulky binnacles are still the norm. The standard Mercury binnacle is fine, still bulky, but modern looking and easy to use. The Mercury range, from 75hp and higher, works with Mercury VesselView touchscreen displays that come in 4in and 6.4in sizes. Other gauges from within the Mercury family will work with the Pro XS but we can’t imagine why you wouldn’t start with its best offering.

 

VesselView and NMEA2000 compatibility

Vessel view for Mercury 115 Pro XS four-stroke

VesselView is intuitive, has strong backlighting and allows fine tuning on how all important data is displayed. The other option, and one we favour, is to link the outboard to the fishfinder in the dash. Our test boat ran a Lowrance elite 9, an entry level multi-function touchscreen that works with sounding gear and has inbuilt GPS for chartplotting. Through NMEA2000, the Pro XS’s key engine data can be shown on the Lowrance, or most other modern multifunction displays. The screen size is the biggest benefit, giving you the ability to monitor more data more clearly, and being able to monitor performance and range against your position on the chart.

 

Servicing and maintenance

Major servicing, or the lack of a need thereof, is one of the Pro XS 115’s strong points. A lifetime maintenance-free valvetrain means less time and money spent at the service agent. The OHC is chain driven, so there’s no timing belt to change, and the head features roller cam followers, meaning no valve clearance adjustments for life. Minor servicing is still needed for fluids and general maintenance, with the first inspection and fluid change needed after 20 hours then annually or every 100 hours, whichever comes first.

 

The Trade-A-Boat verdict

Interior of Mercury 115-Pro XS four-stroke outboard motor

The Mercury 115 Pro XS takes what we have always loved about this range and takes it a step further, with faster response and a more aggressive note, while maintaining economy, light weight and low ownership costs. Matched to a hull like the Anglapro 514 it’s a sharp performer that looks the part too. It would be good for hulls up to around 1200kg or as twins on catamarans and heavier hulls up to around 1800kg.

 

Mercury 115 Pro XS sea trials

Mercury 115hp Pro XS outboard motor running a 14.2in 18P Enertia stainless steel propeller and fitted to an Anglapro 514 Sniper Pro. 40 litres of fuel and two people on board. Range calculated leaving 10% in reserve (total fuel capacity, 100L).

 

Revs

Speed (kts)

Fuel (L/h)

Economy (Nm/L)

Range Nm

 

700

2.00

1.6

1.25

113.64

 

1000

3.00

2.5

1.20

109.09

 

1500

4.00

4

1.00

90.91

 

2000

6.00

6.6

0.91

82.64

Troll speed

2500

9.00

9

1.00

90.91

 

3000

13.00

10.7

1.21

110.45

 

3500

18.00

12.2

1.48

134.13

Optimal Cruise

4000

22.00

16

1.38

125.00

 

4500

25.00

21.2

1.18

107.20

 

5000

29.00

27.4

1.06

96.22

 

5500

31.00

32.1

0.97

87.79

 

6000

36.00

38.1

0.94

85.90

 

6200

38.00

45.3

0.84

76.26

 

* Sea-trial data supplied by the author.

 

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