Wednesday, July 18

Fuel Consumption

Faria Fuel Manager
By Andrew Spaulding and John Staniszewski, Crowley's Yacht Yard

As you can imagine, fuel consumption on any given day depends on many factors. There are a few that the owner of the vessel cannot control, for example, adverse wind and waves will increase fuel consumption over a given distance. However, there are quite a few fuel consumption factors that boat owners can control. 

Before you make a study of which of the below factors you are going to try to use to improve your fuel consumption, install a fuel flow meter so that you can monitor any changes in consumption. There are a few different systems that we would recommend, but the most economical one we have found is a Faria gauge and flow sensor combination named Fuel Manager.

Speed vs. Distance
Typically a lower engine rpm will lead to lower fuel consumption. Although you do need to balance this with the increased time it will take to reach your destination. Your type of boat will influence your decision as well. A planing hull will have a much better fuel consumption to speed ratio if the boat is run on a plane, but not at full throttle.

Keeping your engine it top condition will allow it to give you its best fuel consumption. Out of tune carburetors, old spark plugs, bad ignition wires, clogged fuel filters, worn injectors, dirty air filters, bad gas or diesel, corroded exhaust elbow, clogged coolers and more are all problems that will keep your engine (gas or diesel) from operating properly. If your engine is not in peak maintenance condition you won’t see the best fuel consumption numbers of which your boat is capable.

Drive Train
Your drive train components (transmission, shaft, stern drive or pod drive) will drag your performance down if they are not properly maintained. Typically, manufacturer recommended fluid changes will maintain the internals properly. Inspect the old oil for signs of metal wear…better yet have it and your engine oil sent for an oil analysis every year.

It is important to keep the external surfaces clean of marine growth. There are many products available for the different under water components of your drive train that will fit almost every conceivable water condition from cold, fresh water to hot, salt water. I always tell people to speak with their boat neighbors and find out what works best where you keep your boat since conditions can be localized.

An experienced propeller tuner can tune your propellers for maximum efficiency in the rpm range in which you mostly run. Having the proper pitch and diameter are critical for having good fuel consumption. For the same boat you would want different propellers if you only towed water skiers or if you ran at top rpm to the fishing grounds.

A clean hull with a smooth surface is the largest contributor to fuel consumption that is likely to drastically change over the season due to marine growth. Even a light coating of slime will make your engines work harder. In previous decades only racing sailors paid a lot of attention to their bottoms. Recently with the spike in fuel prices over the last five years, power boaters have turned to bottom jobs to minimize their fuel consumption. No production boat has a perfect bottom out of the factory. Offshore racing powerboats regularly reshape their bottoms for maximum speed. Even small imperfections can cause turbulence in the water flow over the bottom adversely effecting fuel consumption.

The trim (trim tabs, stern drive or outboard angle) at which you run the boat will also affect the fuel consumption. Proper trim will give you more speed for a given rpm. Read related articles for your boat type or contact your dealer for trim suggestions. Don’t be afraid to experiment with this one…once you are on a plane try different trim angles and see if your speed goes up without touching the throttle. If you find a setting that does this, you have found more efficient trim.

Along with trim goes loading the boat properly. The big cooler filled with drinks and ice stuck in the wrong place will force you to over trim the boat to get it to ride correctly. Don’t forget all the rest of the gear – water toys, food, and of course, the people.

1 comment:

Rachael Collins said...

That's very nice post about Fuel Consumption,thanks for the information.Fuel flow Meter