It doesn’t matter where you are in the world, you’ll find a sailing fanatic in a marine showroom asking ‘So, how much does this thing burn?’ It’s a common question and for obvious reasons. You wouldn’t buy a new car without checking its fuel usage first. The same applies to a new boat. Except that accurate fuel calculations can mean the difference between smooth sailing and a red-faced call to the coastguard.
So, it’s important that you get familiar with your boat. Over time, you’ll grow used to its quirks and habits. One day, you’ll be able to throw out fuel estimates in seconds. However, a new boat means starting from scratch and doing things the old fashioned way; with a pen, paper, and lots of numbers. Once you know how fast your tanks empty, you can adjust your fuel provisions to suit all kinds of different open water adventures.
This guide to calculating fuel consumption, brought to you by Asia Pacific’s catamaran specialists, will help you plan and prepare for epic sailing trips.
Getting to Grips with the Basics
Sailing a boat isn’t like driving a car. There are all kinds of circumstances and conditions that can change the way that fuel burns and, specifically, the rate at which it is consumed by the engines. For instance, the calmness of the water is a major factor. If you’re sailing in choppy, turbulent seas, you’ll naturally burn fuel faster. This is why you should always check the forecasted conditions before you head out and adjust your fuel provisions to match.
Making Quick Calculations
For sailing boats, fuel is measured in gallons per hour. The rate of consumption is calculated by working out the pounds of fuel burned up per horsepower developed, per hour. If you know that diesel weighs around 7.2lbs per gallon and gasoline approximately 6.1lbs per gallon, you can start to make pretty accurate estimates. The secret to preparing for long sailing trips is identifying a baseline; knowing how your vessel burns in perfect conditions enables you to decide on sensible increases for stormier voyages.
The typical in tune four stroke gas engine consumes around 0.50lbs of fuel, per hour, for every unit of horsepower. On the other hand, a similar sized diesel engine consumes somewhere closer to 0.40lbs. It is important to remember that these numbers don’t accommodate for weather conditions, the drag of the vessel, and whether or not you’re sailing into the wind. However, they can help you to identify that baseline and work out how much fuel you need to carry for a days’ long trip.
Crunching the Numbers
There’s a handy formula provided below. Grab yourself a pen and some paper and see if you can crunch the numbers for your own boat.
All you’ve got to do is input its horsepower rating and multiply it by the specific fuel consumption average. Divide that number by the fuel specific weight and you should get a nice, round estimate.
How to Estimate Maximum Engine Fuel Usage
GPH = (specific fuel consumption x HP)/fuel specific weight
Constants for Gas/Diesel Vessels
Specific Fuel Consumption: 0.50lb.per HP/0.40lb per HP.
Fuel Specific Weight: 6.1lb.per gallon/7.2lb per gallon.
Formula for a 300HP Diesel Engine
GPH = (0.4 x 300)/ 7.2 = 120/7.2 = 16.6 GPH
Formula for a 300HP Gas Engine
GPH = (0.50 x 300)/ 6.1 = 150/6.1 = 24.5 GPH
Keeping Track of the Averages
Don’t forget that calculating averages in this way doesn’t give you an exact fuel consumption reading. You’ll burn less at cruising speeds. If your boat has digitally controlled fuel injection or direct injection, you’ll burn fuel slower. What it does allow you to do is come up with a sensible ballpark figure, which you can adjust and tweak until it fits the conditions of your trip.
Posted By JenniferA
Updated : 22nd December 2016 | Words : 633 | Views : 1809