|Olga 28 Tardis Photo: John Kessinger|
This graph shows fuel flow (FF) in gallons per hour, efficiency in nautical miles per gallon (NMG), and speed in knots (Kts). The x axis is engine RPM. Tardis is fitted with a 90 HP ETEC outboard.
The gray line (speed in knots Kts) shows a gradual increase to around 9 knots, and then a sharper increase with increasing RPM. The fuel burn increases steadily with RPM, while nautical miles per gallon declines very slowly after the initial drop in the 2000-3000 RPM range.
The steady increase in speed (Kts) vs RPM and fuel flow (FF) reflects the very smooth transition from displacement to planing speed. Its really not noticeable when you are aboard, and this graph gives the figures to support that.
|Olga 28 Tardis slipping along in the East River (CT)|
Photo: John Kessinger