Chimo:
I typically will cruise my R-27/OB at anywhere between 28 and 38 mph. At around the 32 mph & 4500 RPM mark I observe 2.0 MPG (and maybe 15 GPH) on the Yamaha and Garmin displays.
The R-27/OB will fall off plane at around 15-18 mph.
You can use the numbers below for the R-27/OB to evaluate what it is you want.
For our previous R-25 (Classic) which was fully loaded with a heavy Portland Pudgy dinghy on the stern platform, two adults and a fairly full tank of 60 to 70 gallons in same water/sea conditions as for the R-27/OB I would try to cruise anywhere from 10 to 12 mph with RPM in the range of 3200. For a slow cruise I would fall back to around 8 mph. I found it was very hard to get the R-25 anywhere close to 14 mph at WOT of around 3800 RPM, presumable because the boat was fully loaded. When running the R-25 at 12 to 14 mph the it would wander a bit, was skittish when steering manually, but not an issue when on auto pilot as that mechanism handled any skittishness. The fuel burn at my normal cruise speed of 10-12 mph was from what I recall around 5 GPH at 3000 RPM and around 2.5 MPG.
I can cruise my R-27/OB at close to 3x the speed of my R-25 (Classic) using roughly the same MPG of fuel.
I did assembly some performance numbers for you for the R-23, R-27/OB and the R-25SC.
R-27/OB
MPH RPM GPH MPG
5.2 1000 1.2 4.33
6.8 1500 1.9 3.58
8.6 2000 3.1 2.77
10 2500 5 2
11.3 3000 6.6 1.71
14.5 3500 8.2 1.77
18.5 4000 11.8 1.57
30.7 4500 15.3 2.01
35.3 5000 18.7 1.89
39.3 5500 23.6 1.67
42.3 5900 26.5 1.6
R-25SC
MPH RPM GPH MPG
5.8 1000 0.45 12
6.75 1200 0.75 8.7
7.3 1400 1.25 6
8.1 1600 1.8 4.5
9 2000 3.1 3
10 2200 3.8 2.5
11.5 2400 4.6 2.3
12.9 2600 5.6 2.3
16.1 2800 6.4 2.2
18.5 3000 7.4 2.2
R-23
MPH RPM GPH MPG
4.2 1000 0.7 6
6 1500 1.3 4.62
7.4 2000 2.1 3.52
8.4 2500 3.2 2.63
9.5 3000 4.8 1.98
10.4 3500 6.6 1.58
12.7 4000 8.8 1.44
22 4500 10 2.2
30.4 5000 11.8 2.58
34.4 5500 15.8 2.18
38.7 6050 20.4 1.9
I hope the above answers you enquiry. 🙂
I typically will cruise my R-27/OB at anywhere between 28 and 38 mph. At around the 32 mph & 4500 RPM mark I observe 2.0 MPG (and maybe 15 GPH) on the Yamaha and Garmin displays.
The R-27/OB will fall off plane at around 15-18 mph.
You can use the numbers below for the R-27/OB to evaluate what it is you want.
For our previous R-25 (Classic) which was fully loaded with a heavy Portland Pudgy dinghy on the stern platform, two adults and a fairly full tank of 60 to 70 gallons in same water/sea conditions as for the R-27/OB I would try to cruise anywhere from 10 to 12 mph with RPM in the range of 3200. For a slow cruise I would fall back to around 8 mph. I found it was very hard to get the R-25 anywhere close to 14 mph at WOT of around 3800 RPM, presumable because the boat was fully loaded. When running the R-25 at 12 to 14 mph the it would wander a bit, was skittish when steering manually, but not an issue when on auto pilot as that mechanism handled any skittishness. The fuel burn at my normal cruise speed of 10-12 mph was from what I recall around 5 GPH at 3000 RPM and around 2.5 MPG.
I can cruise my R-27/OB at close to 3x the speed of my R-25 (Classic) using roughly the same MPG of fuel.
I did assembly some performance numbers for you for the R-23, R-27/OB and the R-25SC.
R-27/OB
MPH RPM GPH MPG
5.2 1000 1.2 4.33
6.8 1500 1.9 3.58
8.6 2000 3.1 2.77
10 2500 5 2
11.3 3000 6.6 1.71
14.5 3500 8.2 1.77
18.5 4000 11.8 1.57
30.7 4500 15.3 2.01
35.3 5000 18.7 1.89
39.3 5500 23.6 1.67
42.3 5900 26.5 1.6
R-25SC
MPH RPM GPH MPG
5.8 1000 0.45 12
6.75 1200 0.75 8.7
7.3 1400 1.25 6
8.1 1600 1.8 4.5
9 2000 3.1 3
10 2200 3.8 2.5
11.5 2400 4.6 2.3
12.9 2600 5.6 2.3
16.1 2800 6.4 2.2
18.5 3000 7.4 2.2
R-23
MPH RPM GPH MPG
4.2 1000 0.7 6
6 1500 1.3 4.62
7.4 2000 2.1 3.52
8.4 2500 3.2 2.63
9.5 3000 4.8 1.98
10.4 3500 6.6 1.58
12.7 4000 8.8 1.44
22 4500 10 2.2
30.4 5000 11.8 2.58
34.4 5500 15.8 2.18
38.7 6050 20.4 1.9
I hope the above answers you enquiry. 🙂