The following performance estimates are based on the actual measured performance of the 37% model.
Pcat Performance Estimate March 4 2002
Performance data from 37% model. 7.4 Kn with 2.5 HP engine. The engine was chokey and had under pitch prop. The boat weight was 10% over design. I have factored in these and normalized the model performance to 8.0kn with 2.5 HP.
Scaled to 100% 13.15 Kn at 49.4 HP. Further normalize for the larger engine by taking this speed ^3 X 1.06 for 55.3 HP = 14.0 Kn
Tankage 250 U.S. gallons. Range number represent a 10% fuel reserve.
There are two sets of estimates in the chart. One based on a prop factor of N2.2 which would be for a standard prop and one of N2.7 for the ducted props in use. The ducted props absorb more horsepower from the engine at the same RPM.
The specific fuel consumption is listed for the engine and the maximium continous HP rating. For the N2.7 case about 2750. This produces a speed of around 13kn or about 320 kn miles per day. Range would be around 1200 kn miles in that case.
Likely fast cruise would be at around 2000 RPM and 10 kn with a range of about 2000 kn miles.
Standard cruise would be at just under 1600 RPM at 8 kn with a range of 2800 kn miles at about 12 kn MPG and .7 GPH fuel consumption.
Doing our Nordhaven impersonation would be at 1150 RPM and 6 kn with a range of 3900 kn miles and at 17 kn MPG and .35 GPH fuel consumption.
RPM Specific Fuel MAX Cont HP HP N2.2 Speed Kn MPG Range HP N2.7 Speed Kn MPG Range GPH 3000 175 49.9 55.3 14.0 4.7 1049 55.3 14.0 4.7 1049 3.0 2900 175 50.5 13.5 4.9 1108 51.3 13.6 4.9 1098 2.8 2800 172 46.8 45.9 13.0 5.3 1194 47.5 13.2 5.2 1169 2.5 2700 172 44.5 41.6 12.5 5.6 1266 43.9 12.8 5.4 1226 2.3 2600 168 43.3 37.6 12.0 6.1 1378 40.4 12.3 5.9 1319 2.1 2500 168 41.5 33.8 11.5 6.5 1469 37.0 11.9 6.2 1391 1.9 2400 166 40.6 30.3 11.0 7.1 1587 33.8 11.5 6.6 1486 1.7 2300 166 27.0 10.5 7.6 1701 30.8 11.1 7.0 1571 1.6 2200 164 36.9 23.9 10.0 8.2 1852 28.0 10.7 7.5 1684 1.4 2100 164 21.1 9.5 8.9 1996 25.2 10.2 8.0 1794 1.3 2000 162 33.8 18.5 9.0 9.7 2186 22.7 9.8 8.6 1934 1.1 1900 162 16.1 8.5 10.6 2376 20.2 9.4 9.2 2074 1.0 1800 162 32.6 13.9 8.1 11.5 2595 18.0 8.9 9.9 2223 0.9 1700 160 11.9 7.6 12.8 2885 15.9 8.5 10.8 2424 0.8 1600 160 10.1 7.1 14.1 3183 13.9 8.1 11.7 2628 0.7 1500 164 25.8 8.5 6.6 15.3 3444 12.0 7.6 12.4 2800 0.6 1400 164 7.1 6.2 17.1 3837 10.3 7.1 13.6 3069 0.5 1300 168 5.8 5.7 18.8 4228 8.8 6.7 14.6 3293 0.5 1200 168 4.7 5.2 21.3 4797 7.4 6.3 16.2 3653 0.4 1100 172 3.7 4.7 24.0 5409 6.1 5.8 17.8 4007 0.3 1000 172 2.8 4.2 28.4 6393 4.9 5.3 20.3 4570 0.3
Copyright © 2003 Tony Bigras.