{"id":42952,"date":"2016-11-18T13:46:40","date_gmt":"2016-11-18T18:46:40","guid":{"rendered":"https:\/\/setsail.com\/?p=42952"},"modified":"2016-11-18T13:46:40","modified_gmt":"2016-11-18T18:46:40","slug":"using-modern-tools-to-manage-and-extend-cruising-range-under-power-2","status":"publish","type":"post","link":"https:\/\/setsail.com\/using-modern-tools-to-manage-and-extend-cruising-range-under-power-2\/","title":{"rendered":"Using Modern Tools To Manage And Extend Cruising Range Under Power"},"content":{"rendered":"

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\nWe begin writing this post halfway through a 4,700 nautical mile passage, under power, against the trade winds and prevailing current, between French Polynesia and Panama. The accurate fuel consumption data available with tier II and tier III\u00a0diesel engines has completely changed our approach to fuel management and the future passages we are thinking about undertaking…<\/p>\n

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…and we thought some comments on what we have learned in the initial 10,000 nautical miles of cruising aboard FPB 78-1 Cochise<\/em> might be of interest. Although Cochise<\/em> has a range in excess of 5,500 NM under these\u00a0conditions, and the current voyage distance is easily within\u00a0Cochise’s\u00a0<\/em>range, we are making use of a few simple tools which allow us to precisely analyze and manage fuel data for this trip, as well as record it for future use. This is a long and detailed post, based totally on real world numbers. Even though your own situation will probably be different, the process we are using has universally applicable principles.<\/p>\n

We start off with the numbers, then we will look at what can be done to improve efficiency, followed by\u00a0a few words on weather tactics. When looking at the following numbers, keep in mind that they are for a large, relatively high windage yacht, traveling for the the most part directly into the wind and seas. During much of the passage there is also a substantial current against us, varying between .5 and 1.5 knots.<\/p>\n

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\nThe whole process\u00a0begins\u00a0with precise fuel consumption data now available on modern engines and some N2K systems. In our case, each of the John Deere 6068 AFM 75 diesel’s \u201cPowerview\u201d screens has a readout of total fuel burned. We integrate the fuel burned, distance covered, distance to go, and fuel capacity into a spreadsheet to quickly give us answers on where we stand. (The same can easily be done with a calculator on a piece of scratch paper.)<\/p>\n

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\nAfter entering this data into our paper log, we then transfer it to the spreadsheet. At a minimum this is done daily. But if there is a major change in conditions, we will capture it more often for future reference. With a database of real world conditions on which to draw, we can make intelligent assessments of potential passages, before<\/em> heading out, and understand where we stand while underway. Without it, say with just smooth water data or marketing-based fuel consumption propaganda, one needs to add healthy doses of safety factor to the calculations, to make sure lack of accurate information doesn\u2019t catch you short mid-ocean.<\/p>\n

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\nWhat we are after is the\u00a0total<\/em>\u00a0fuel burned, inclusive of electric and hydraulic requirements. Since we do not need to run a generator underway – the engine driven alternators each have a five kW capacity – keeping total score is simple. Likewise, during passaging stabilizer and rudder drag can be substantial, not to mention windage and rough water wave drags. For the fuel burn data to be meaningful it has to include all of these elements. Since this voyage has been almost entirely uphill to date, in a warm environment requiring air conditioning, the data we are capturing is worst case scenario in terms of fuel consumption.<\/p>\n

Speaking of worst case, take a look at the numbers\u00a0in the photo above. These are high on fuel burn and slow on speed, in spite of the DC load being carried mainly by the solar array during the middle of the day. Butting heads with the trade winds generates these kinds of numbers. Better to know ahead than have to learn the hard way from a fuel shortage.<\/p>\n

We will start with using the data from 0600 this morning as an example. The spreadsheet initially makes the following calculations for us:<\/p>\n