Posted on 10 October 2008
Is there anything simple and easy, yet highly effective, that I can do to save fuel?
A: Yes, if you have an inboard with permanently submerged running gear. It’s simple and usually easy: Regularly clean your running gear — propellers, struts and shafts — of barnacles and other growth.
It’s amazing how even light barnacle growth on this gear can impede the efficiency of your prop and significantly increase fuel consumption. Barnacles can cover a propeller blade quickly. At first they’re very small and feel like a coating of very coarse sandpaper if you rub your hand (gloved) over the blade. Even at this stage they’re wasting fuel. And they’re going to keep growing — rapidly, if conditions are right. And conditions probably are if you’ve got barnacles in the first place.
While growth on the strut and shaft perhaps isn’t as much of a detriment, it’s also significant. Barnacles here impede the water flow across the blades. Even barnacles on the hub of the prop will diminish efficiency.
There are many products marketed for use on the propeller, strut and shaft. Unfortunately, I’ve never seen any of these work for very long. How long they work depends not just upon the passage of calendar days, but also on how many revolutions your propellers make (how often you go out and at what speed the props turn); the type of water you’re in; and how well the product was applied.
A propeller, even on a slow boat, spins very fast in the water. To stay on the prop, a coating has to adhere much more tightly than a coating on the boat’s bottom, which moves through the water much more slowly. Also, the coating that keeps barnacles and other life from growing may not be of the same effective material that can be used on the hull because of the dangers of reaction with metal. So while you may have applied a great product on your gear, you should assume that after a while, probably long before your season is out, you may need to give it some help.
Resolving this problem and adding miles to your gallons can be easy and fun. I simply jump over the side with a paint scraper and scrape barnacles and other growth off as needed. But this method is not for everyone and can be dangerous, particularly if you don’t have the skill, stamina and other necessary attributes to do it.
If you do it yourself, be sure to do it in safe circumstances. These include water clear enough so you can see, no current, no waves or wakes, a safe water temperature so hypothermia isn’t an issue, water that’s not so shallow that you could get caught against the bottom, a familiarity with your running gear so you don’t get entangled, an assistant who’s also capable and has the skills and stamina, no bad critters (such as stinging nettles or worse), no nearby dangerous pilings or other structures, and enough common sense so you don’t push yourself.
For protection, wear heavy-duty rubber (or similar) gloves and a long-sleeve dive shirt. (Become familiar with how this and anything else you wear affects your buoyancy and maneuverability. Don’t wear anything that can snag on running gear, etc.) Cuts from barnacles and other marine growth, anywhere on your body, can result in extremely serious infections. Also, wear full flippers (if strap flippers, wear dive booties) to help you swim and to protect your feet.
Of course, you’ll need a mask and snorkel. I sometimes use a hookah dive system made by Brownie’s Third Lung for this and other underwater projects (www.browniedive.com). This makes the job quicker and easier. Obviously, you need the training, skill and stamina to use this type of equipment.
If needed, have a professional diver go down periodically to clean this gear. An expensive full bottom cleaning often isn’t necessary, especially if you haul out regularly, so specify that you only want the diver to clean the prop, strut and shaft. It’s also important to have a clean bottom, but usually the annual coating of anti-fouling paint takes care of this, even though the running gear is fouled.
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