It is never easy to quantify exactly how efficient a marine engine really is. Every boat is slightly different to its nearest competitor. Weather and tidal conditions are variables that cannot be ignored. Even the latest factory fuel flow meters, using pulse metering technology, are still only as accurate as the software within. Like for like, back-to-back testing is the only way to see how comparable engines truly perform, and for this you need two identical test boats.
Thanks to MRL Marine having rigged two 9m 900GTs – one with the outgoing 200hp supercharged Mercury Verado and the other with Mercury’s latest 225hp V6 (as featured in the last issue) – we were able to see how Mercury’s claims for their new engine stack up. Having tested the 900GT with twin 200hp Verados, I know they work very well on this boat. I have also tested two of the new 225hp V6s on the back of an XO270, which impressed with the broad spread of power these motors put out. However, the Stingher 900GT and the XO270 are very different boats.
Our back-to-back test was as near clinical as a marine engine test could be. The boats were identical, bar the fact that the boat fitted with the new V6s had an extra pair of seats and an extra 100 litres of fuel over the Verado-powered boat. As the pictures show, the sea conditions in Southampton Water were as identical as you could get them. All performance runs were two-way averages to account for tidal conditions. MRL Marine are meticulous in their prop testing, with the assistance of Neil Holmes. After the best part of a week trying different propellers, they finally settled on the optimum prop for the new V6, as they had previously done with the Verado engines fitted to the 900GT.
The first impression of any boat is generally how quickly it gets up onto the plane. That initial low-down grunt felt when you push the throttles home is generally a good indication of how things are going to progress. In this department, the 900GT powered by the new V6 is very quick off the mark, with a relentless spread of power all the way up to 6000rpm. The only comparable engine I have experienced that competes in low-down power is the 2-stroke 200hp BRP E-Tec G2. By the nature of being a 2-stroke, this engine will always be hard to beat in torque terms.
Having said that, the Verado boat is also quick, but the figures recorded by us on both boats show that the new engines push a Stingher 900GT up to 30mph (26 knots) about half a second quicker than a pair of 200hp Verados. You may well say this is splitting hairs and nigh on impossible to gauge accurately, but this half-second margin increased to 2 seconds when we recorded a zero to 50mph (43 knots) time. When we did a rolling run from 26 knots to 43 knots, the naturally aspirated V6-powered Stingher was 1 second quicker. Another interesting aspect that was thrown up is that the V6-powered boat could hold planing speed down to 15 knots, while the other boat dropped off the plane at just over 16 knots. All I can say on this matter is that with a pair of 216kg V6s, compared to the earlier-generation supercharged 200hp Verados, you have 30kg less hanging off the transom. One thing is for sure, the new engine is relatively quiet. However, when you really want to hear it, when accelerating hard, it has a healthy V6 growl. Multi-chamber mufflers keep the noise down, and routing the exhaust down through the middle of the 64-degree V gives the engines a slim profile, enabling them to be mounted just 26 inches centre to centre. A simple but very effective feature is the service hatch in the top of the cowl. This enables quick oil checks and refilling, as well as providing a single-lever catch to facilitate removal of the top cowl.
Of course, the biggest issue is always fuel efficiency. Mercury are making big claims in this department regarding their new V6, as well as the rest of their latest range. This is always par for the course with any engine manufacturer, and in Mercury’s case they attribute these gains to their advanced electronic engine control – in simple terms, ‘proactive ECU-controlled fuelling’, which effectively delivers specific fuel needs while enhancing torque in the process. However you try to skin this cat, the findings of our fuel tests are listed below, giving a clear thumbs up for the new V6.
RESULTS
Engine: Mercury 2 x V6 225hp
Propellers: 21″ pitch Tempest Plus (no vent holes)
Load: Fuel 220L, fresh water 20L, plus one crew
RPM Speed (mph) Speed (knots) Fuel burn (Lph) NMPG
600 3.7 3.2 4.0 3.6
1000 5.8 5.0 8.2 2.8
1500 8.3 7.2 14.2 2.3
2000 11.5 10.0 20.6 2.2
2500 21.0 18.3 24.8 3.4
3000 28.7 25.0 33.2 3.4
3500 36.1 31.4 43.2 3.3
4000 41.5 36.0 60.2 2.7
4500 48.0 41.7 76.6 2.5
5000 52.1 45.3 94.4 2.2
5500 57.8 50.3 135.0 1.7
6000 (WOT) 64.5 56.1 152.4 1.7
Slowest speed on the plane: 17.4mph (15.1 knots)
Hole shot: 2.9 seconds
0–30 mph: 4.7 seconds
0–50 mph: 8.3 seconds
30–50 mph: 4.8 seconds
RESULTS
Engine: Mercury 2 x 200hp supercharged Verado
Propellers: 23″ pitch Tempest Plus (no vent holes)
Load: Fuel 120L, fresh water 20L, plus one crew
RPM Speed (mph) Speed (knots) Fuel burn (Lph) NMPG
650 4.1 3.6 3.3 5.0
1000 6.7 5.8 5.8 4.5
1500 8.9 7.7 10.0 3.5
2000 11.9 10.3 16.1 2.9
2500 18.9 16.4 22.9 3.2
3000 26.0 22.6 32.8 3.1
3500 31.9 27.7 37.9 3.3
4000 37.4 32.5 50.7 2.9
4500 44.2 38.4 67.6 2.6
5000 47.3 41.1 83.3 2.2
5500 52.5 45.6 121.0 1.7
6036 (WOT) 59.9 52.1 151.0 1.6
Slowest speed on the plane: 18.7mph (16.3 knots)
Hole shot: 3.2 seconds
0–30 mph: 5.2 seconds
0–50 mph: 10.3 seconds
30–50 mph: 5.8 seconds
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