If you own a dinghy, a sail cab or engine, or any other nautical vehicle equipped with an endothermic engine (benzine or diesel) the consumption has an important impact on the use of the vehicle and its safety.
On use because they are related to operating costs, consuming less means navigating more on a seasonally-high budget; to always have a certain reserve of fuel available in order to deal with any unforeseen events that can be found at sea (rapidly worsening marine weather conditions, rescue of units or people in distress, etc.).
Of course, with today’s datasheets it is very easy to read the data declared by the engine manufacturer, make your own assessments and decide.
But as we have the opportunity to check daily with our inseparable cars, the consumption declared by the manufacturer is decidedly optimistic and almost always differ, often not by little, compared to the consumption that is seen in the daily use of the Vehicle.
Even in the nautical field things do not change as much and the now known reference parameter liter/hour has a rather indicative value as the manufacturer in the approval phase does not take into account the conditions in which the vehicle will be to navigate (formation of the sea, currents, winds, state of living work, etc.), so the consumption will be real only with the engine that delivers the maximum power, provided that the elica makes it work properly.
For the security issue, the unit commander must apply all the minimum measures to avoid the unpleasant situation of running dry…
The estimation of consumption at a certain number of laps for good rule should be considered to be 30 more or alternatively the reduced speed of 30 and therefore also the shorter passable distance of that percentage.
All seemingly very simple and linear. Are you sure?
In fact, under optimal textbook conditions, the above references are quite reliable. But what are the factors that can make mistakes in these estimates?
- Ordinary maintenance of thrusters (candles, injectors, filters, ducts, pumps, etc.).
- Cleaning status of the hull and appendages (including the helix).
- Load size and distribution (including fuel), changes in trim can affect the operation of the thrusters.
- Piloting techniques.
Let us dwell on this last point assuming that we have a vehicle in excellent state of maintenance; we’re going to have to make two clear distinctions and these are related to the type of hull of our boat.
For gliding hulls, the cheapest pace compared to nautical mileage is reached at speeds of just above the minimum gliding speed.
In the event that, for safety or comfort reasons, it is not possible to follow this line and decide to move, it is advisable to keep a distance from the critical speed beyond which the hull begins to glide.
This is because at this stage the hull is practically stalled, at the mercy of turbulence and resistances that increase consumption and greatly reduce the comfort of navigation.
For disland hulls (including sailboats) the resistance, on the other hand, simply increases according to the speed up to that of hull (about one knot per meter in length at the buoyancy); After this speed the increase in power turns into pure waste of fuel.
In order for all these precautions not to remain only theoretical, the technology has provided us with the very comfortable FMS-Fuel Management System, the formidable dashboard computers that allow us to observe in real time all the consumption data in various forms: liter/hour, miles/litre, residual range in miles etc.
Through an FMS you can better adjust the speed and consumption even when the hull is not clean or the weather conditions are adverse, always having everything under control.
In this way the commander becomes aware of the real consumption of his unit and is incentivized to optimize the driving style according to the consumption detected. This translates into a significant saving that allows you to depreciate the costs of buying and installing the computer in a short time and, above all, reduces the environmental and economic impact due to excessive fuel consumption.