Improving Your Boats Fuel Economy

Here are some tips from A to Z Boatworks to help you get some extra mileage out of your fuel this coming boating season.

Shedding those few extra pounds this spring doesn't just apply to us, it also should apply to our boats.

If it takes you two weeks or longer to use up a full tank of gas - Stop filling your tank! Remember that gasoline weighs about 6.5 pounds per gallon so if you are carrying around 50 gallons of extra fuel over the weekend that you won't need, you are also carrying around an extra 325 pounds on your boat. On larger boats you could be carrying around an extra 100 gallons or more which is 650 pounds plus. Your engines have to work harder and use more fuel to get that weight up on a plane and keep it cruising. Also remember that today's gasoline will start to go stale in two to three weeks. So always add fuel stabilizer to your fuel when you go to the gas dock.

Make sure your boat is not holding more water than it needs. Don't fill up your fresh water tank if you don't need it. Water weighs just over 8 pounds a gallon so a 20 gallon fresh water tank adds 160 pounds to your boat. Also check below decks and make sure your boat isn't holding water anywhere. Bits of debris can block drainage holes in the stringers or bulkheads which doesn't allow the water to get to the bilge pumps to get pumped overboard. Also, make sure all of your livewells and fishboxes are pumped dry when not in use. A full 40 gallon livewell adds 320 pounds. Add that to your extra 100 gallons of fuel and you're up to half a ton of extra weight!

If your boat is equipped with a head with a holding tank, get it pumped out. I'm not sure how much that stuff weighs a gallon, and I'm not going to weigh it either, but I'm pretty sure it's more than water. Pumping it out regularly will help keep your extra weight down and also is better for the life of your boats plumbing. Pump outs are available now both in the North River and also in Scituate Harbor at the town marina by the Harbor Master's office. To schedule a pump out in the river contact the guys of Harbor Mooring at 781-544-3130 and they will come to you.

Lastly on the weight issue, take the extra stuff home. All of those extra sweatshirts, towels, empty bottles, etc. adds up to extra weight. It may be a hassle to bring it all back when you need it, but now a days every little bit helps.

The smoother your boat can go through the water the more economical it will be. There are a couple of ways we can improve this.

Make sure the boat is prepared in the spring. A good coat of bottom paint goes a long way to keeping barnacles and other growth from forming on the bottom and increasing drag. Making sure that the bottom is as smooth and uniform as possible is important to keeping the boat more fuel efficient as well. If you have an older boat that has been building up layers of conventional bottom paint over the years, you may want to consider getting the bottom stripped before applying a new coat of ablative bottom paint this spring. There are a couple of local companies that specialize in the environmentally friendly processes for removing bottom paints. Feel free to give us a call for more information on the process if interested.

Watch your bottom during the season. If you notice that your boat is growing a "beard" get out the scrub brush and scrub it off. The cleaner you can keep the bottom the more efficient your boat will be.

Also consider the drag above the water line. Canvas enclosures and bimini tops are great to get out of the weather, but if they are not needed, take them down. Most of the canvas enclosure windshield connectors we see are almost vertical. Not much in the way of being streamlined. Take them down and let the wind flow through the enclosure and not slam into it head on, adding to the drag on the boat.

No I'm not recommending new curtains or crown molding. Use the trim capabilities of your engines or drives. That switch on the control handle is not just for getting the motor out of the water in the slip or for when maneuvering around the rocks.

Trim the drives or outboards all the way down when accelerating onto plane. This will help push the nose of the boat down faster, getting the boat on plane quicker so you can settle into an economic cruising speed. Once up on plane, run the trim of the drives or outboards up. As they tilt up you will notice the bow of the boat begin to rise in relation to the horizon. At the same time you should notice your engine's RPM rise as well as your MPH. This is because the higher the bow lifts the less of the boat is dragging in the water. If you've never done this, go out and "play" with the trim on your boat. The higher you can run your trim COMFORTABLY, the more fuel efficient your boat will be. If you notice a drastic increase in volume from your engine, a quick jump in engine RPM sometimes accompanied by a drop in speed, or if the bow of your boat starts to bounce up and down (called porpoising), you've trimmed up too much and should trim back down to an acceptable height.

Try to avoid your trim tabs if possible. The more you lower those tabs into the water the harder you are working those engines to maintain the same speed. If the boat is leaning to port try shifting the weight on deck to level out the boat. Slide a cooler to starboard or get one of the crew to move over. Make sure when the boat is at rest that it floats level. If she leans to port at rest, she will try to do the same at speed.

If you don't have to run wide open throttle from point A to point B, don't! Find the sweet spot for fuel economy with your boat. Most boat tests that you see and read about show the best fuel economy for a boat is around the ¾ throttle setting, usually between 4000 and 4500 for outboards and 3000 to 3500 for inboards. After that point fuel consumption usually goes up, and fast. You may get there faster, but you will burn a lot more fuel. If not equipped you may want to consider investing in a fuel flow meter that you can use to monitor your gallons burned per hour and calculate which speed gets you the best miles per gallon. One unit that we like is the Northstar F210 Fuel meter that will show fuel flow, fuel used on trip, total fuel used, fuel remaining in tank and has an alarm for low fuel. This unit retails for 139.99 and fits in the same size hole as most 2" engine gauges.

When maneuvering at slow speeds avoid plowing, that speed where you have to stand on your tiptoes to see over the bow. This speed is actually harder on your motors than wide open throttle. It would be the equivalent of climbing a steep hill. Not a very efficient speed. So in speed limit areas keep the speed down lower so the boat stays mostly level, or if allowable push the speed up and get her up on plane.

We'd also highly recommend that you make sure your engines have the correct propellers installed on them. Each manufacturer has a recommended wide open throttle RPM and your motor should get as close to that RPM as possible to be its most economic. If an engine is rated for 5500 RPM and it only gets 4500 RPM due to an incorrect prop that motor is working too hard internally and is not giving you the best economy. Check with us or your technician to find out what the recommended RPM for your engine is and make sure you get there with the proper trim. (Don't forget the trim!) Once you are sure your motor is propped correctly, if weather allows, try and go to wide open once a trip to make sure that RPM stays consistent through out the season. If you notice a drop in RPM of 200 or more something is going on. The boat may have gotten "heavier", it may be building growth on the bottom or something may be going on with the motor itself. Check for all the things we've mentioned above and if that doesn't fix it contact your service guys to check out the motor.

Well there you have it. Hopefully we have given you some ideas and tips that will save you some fuel and put a little money back in your pocket that you can use for other important things... like tackle or supplies to fill the cooler. Go easy on the ice though. Remember water weighs 8 pounds per gallon.