Tips to Stretch Your Gas Dollar
With fuel prices soaring, it pays to do a little dieting to get the most miles for your money. Chances are, if your boat or engine is older than three years, it’s already consuming more fuel than when it was new. An awareness of the conditions that effect fuel economy and how to rectify them ensures your boat and engine combination is providing you with the best fuel economy. Most gasoline marine engines operate on two-cycle or four-cycle type technology. Two-stroke engines have a very high horsepower-to-weight ratio. When combined with computer-controlled direct fuel injection (DFI), such as Mercury Optimax, these engines are low emission but do consume typically more fuel than an electronic fuelinjected (EFI) four-stroke engine of the same horsepower. In contrast, four-stroke engines have a very low horsepower-to-weight ratio and are usually much heavier than twostroke engines of the same horsepower. Both EFI and DFI two- or four-stroke models, however, are more fuel-efficient than carbureted versions of the same engine. When factoring fuel costs for two-cycle engines, oil consumption must be taken into account as this type of engine consists of a total loss oiling system - the oil and gasoline are mixed together and burned off during engine combustion, whereas a four-cycle engine has oil that remains in the crankcase separately from the fuel. The quality and type of oil or lubricants used in marine engines, transmissions, generators, etc. can also affect fuel economy. Many technicians employ products such as Royal Purple lubricants that claim to provide the best in fuel economy. I always advise using only the engine manufacturer’s minimum or better recommendations for lubricants as specified in your engine service manual. Diesel engines, which utilize a mechanical fuel injection system, have always been the best choice for sailboats and large motoryachts. The addition of an electronic processor or computer to modern diesel engines dramatically increases the engine’s drivability and fuel economy. Most gas and diesel marine engines that have an engine processor or computer can provide fuel consumption numbers through a shop tool called a Scan Tool or on a laptop with the correct diagnostic software. Don’t rely on the “fill ’er up, run and fill ’er up again” method to guesstimate fuel consumption. Consider installing a fuel flow meter, such as FloScan, to monitor fuel consumption. Just set the throttle at the most fuel-efficient speed. A flow meter also displays fuel remaining so you can carry less fuel and you’ll not fret about running out. Considering that gasoline weighs 6.1 lb. per gallon (2.7kg per 3.78L) and diesel a pound (.45kg) more, cruising with less than full tanks reduces boat weight, which translates into better fuel economy and money saved.
Engine Checks The quality or the state of engine tune has the most direct effect on fuel economy. Engine parts, such as distributor caps, spark plug wires, spark plugs and filters, need inspecting annually and replacing every three years or every 300 hours, whichever comes first. After three years, the performance of the boat drops off so gradually that it’s not noticeable to the owner or operator. Be assured that, in order to get peak fuel efficiency from your engine, it must be in tip-top running condition. More throttle means more fuel! Most marine gasoline engines have a maximum engine rpm in the 5,000 to 6,000 rpm range. This high rpm range, obviously, is not within the engine’s best fuel efficiency range. On average these engines get their best fuel efficiency in the 2,500 to 4,000 rpm range. An engine operated at 75% throttle versus operation at 100% throttle uses approximately 50% less fuel regardless of which fuel management system the engine utilizes. Further, an EFI engine is approximately 30% more fuel efficient when run within the normal duty cycle of 2,500 to 4000 rpm range, compared to that of a carbureted engine of the same horsepower and design. Duty cycle is the amount of running time and engine speed that the manufacturer recommends when operating an engine and the information is available from the manufacturer. Most pleasure craft gasoline engines have a duty cycle of no more than 75% throttle for up to three hours continuous operation and then the engines should be shut down and allowed to cool off. Commercial engines obviously have much more vigorous duty cycles and can be run continuously for greater lengths of time. Ensuring your engine is well maintained and operated within the engine’s duty cycle promotes good fuel economy and long engine life. Fuel Stats Most boat companies should be able to provide you with approximate fuel consumption values for their particular boat and motor combinations. You could compare this data to your current consumption values to determine if moving up to a computer controlled EFI or DFI engine is cost effective. For example, a 32-foot (9.7m) express cruiser with twin 350 cid carbureted engines consumes around 16.5 gallons (62.4L) per hour. The same 350s with EFI use 14.5 gallons (54.8L) per hour at 3,500 rpm. Be aware, though, that there is no way to accurately predetermine the fuel consumption of any boat and motor package due to changes in the boat’s operating environment. A boat run at the same engine speed in saltwater on a cool, clear day has better fuel economy than that same boat operated at the same speed in freshwater on a hot, humid day due simply to the operating conditions. Shed the Weight Does your boat need to go on a diet? How can I be delicate here? Most boats that I have worked on over the years have three times the “stuff” socked away onboard than what’s needed for comfortable cruising. Put your boat on a diet and get rid of any excess cargo, debris, old supplies, mildewed and soggy lines, “stuff” you haven’t used in years and any other non-essential equipment that doesn’t compromise any safety standards. Ensuring that your boat is “physically” fit also adds to fuel savings. Another common problem with maturing boats is they tend to hold more water both during operating season and while in storage. Functioning bilge pumps with automatic float switches keep the boat bilge dry when the boat is afloat and a cover or shrink wrap during layup are essentials if you want to keep the fiberglass hull dry. Another common area where boats gain weight is the flotation foam, typically used on runabouts. These lightweight foam blocks are often discovered to be water saturated and very, very heavy. Once you have ensured the boat is as light as possible, try to lower the center of gravity. In the case of planing hulls, position gear and equipment so that a minimum of the hull’s bottom is in contact with the water to reduce drag. Loading two weeks’ worth of vacation supplies in the bow will not be in the best interests of trimming the boat for fuel economy. Don’t Be A Drag Try to keep the boat balanced bow to stern and side to side. Correct use of power trim systems on sterndrives and outboards also reduces fuel consumption by reducing hull drag. Less drag means more fuel economy. That also means keeping the bottom of the boat free of marine growth (barnacles, zebra mussels and vegetation) is essential. Inspect propellers for bends, nicks and any other damage and check skegs, struts and rudders for proper alignment. Displacement hulls such as large cruisers and sailboats under power also benefit from a clean hull, correct propeller selection and placement of loads to encourage a low center of gravity and a level attitude afloat. Trolling tabs/plates and trim tabs should be checked for proper operation to ensure the tabs can be lifted when not required, ensuring minimum drag. Don’t let high fuel prices stop you
from going boating. Get smart about
maintenance and your driving habits and
stretch your fuel economy not your wallet.. |
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