 |
 |
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
|
||||||||
MORE INFORMATION Boats
Are Not Pressurized Like Cars BOATS ARE NOT PRESSURIZED LIKE CARS! Cars utilize a pressurized system to deliver fuel directly to engine injectors. This is done under high pressure delivered by a pump within the fuel tank to assure peak performance and economy. This type of system also does not permit air or fuel to escape from the tank during operation and does not have a vent to relieve pressure. Cars also have a carbon canister to control vapor emissions. According to the Boat Safety Act of 1971, pressurized systems are not permissible for boats. If they were, in the event of a failure anywhere in the system, a large amount of fuel would collect in the bilge creating a very explosive situation. In addition, boats pound more while underway and fuel gets jostled, causing additional expansion. The pressure created must be released – and on boats, it is released though the tank’s breathing vent. Shake a can of soda and open the top and you’ll know the explosive answer as to why boat fuel systems aren’t allowed to be designed like cars. When refueling rapidly or overfilling your fuel tanks, boats vent air that is often mixed with fuel. During refueling, gas goes into the tank and displaces air. The air escapes out through your boat’s fuel tank vent. When the tank is nearly full and there is no more air to displace, frothy fuel begins to bubble out into the water or onto your decks. Additional expansion of the fuel (and subsequent leaks out of your boat’s fuel vent) may occur when cool fuel is pumped from underground storage tanks into the boat on a hot day, or during the rise and fall of outside temperatures. For these reasons, you should never top off your fuel tank and you should always leave 10% of tank capacity for expansion. Also try to refuel when you are headed out, not when you are putting the boat away. Trailer boaters should take the added precaution to fuel their boats on a level surface, or air pockets can form in the tank that can lead to the burping or back splash of fuel. GROUNDING ESSENTIALS and a SPECIAL WARNING: A Caution About Grounding Your Deck Fill: Please check with your installation instructions regarding grounding requirements or refer to a marina or boat yard that is versed in American Boat & Yacht Council (ABYC) construction standards. Because fuel nozzles are metal and the flow of fuel through it generates static, a small but dangerous spark (called an Electrostatic Discharge or ESD) can occur when the nozzle is inserted into a metal filler neck. To prevent sparking, a ground wire must be attached from the metal deck fill unit to the boat’s bonding system. Also, it is important that the nozzle remain in contact with the metal deck fill at all times while refueling. Never wrap a nozzle in an absorbent pad or rag so that it prevents a good contact between the nozzle and metal body of the deck fill. When refueling portable fuel tanks, always place directly on the ground, never on a plastic truck bed-liner or a dock made of synthetic plastic wood. Good contact between a portable tank and a solid grounded object is essential. Special Warning for Plastic Body and Metal Fuel Caps: Deck fill units that have a plastic body with metal components such as a metallic lid or metal retaining chain, are NOT to be grounded. Read the important Safely Message & Technical Bulletin issued by the United States Coast Guard (USCG) in February 2005:
WHY ARE BOATS FUEL TANK GAUGES INACCURATE? We wondered why so many boats have problems with fuel gauges so we asked around about why gauges seem to be inherently inaccurate. The response from manufacturers was “don’t blame the gauges!” Rather, the most common culprit cited was the sending unit (that’s why tapping on the glass rarely works)! Most fuel gauges rely on a sending unit with a float that is often manufactured by a separate company. The float rises and falls with the fuel level and sends an electronic signal corresponding to a unit of measurement (usually ¼ tank increments) on your fuel gauge. Often, new boats are shipped on trucks when the fuel tanks are empty, causing the sender to bounce and become misaligned. Another potential reason for inaccurate readings is that tanks are often designed to fit the bottom contour of a boat and sometimes shaped like a triangle. This means that the sender and gauge must be compatible with unique tank shapes, and dropping in a stock sending unit is not likely to read accurately. In addition to issues with the float arm and tank shape, there may be calibration, voltage fluctuation or grounding issues at play. The bounce, heel, trim and general abuse that a boat takes when operated affects proper readout as well. Have you ever come off a plane and suddenly have a different readout? If your boat has some fuel gauge issues: 1) Manually inspect the sending unit in the fuel tank. Be certain it has no internal rubbing or an obstruction. 2) Check for proper voltage, wiring and ground connections and determine if the sender and gauge are compatible. 3) Visually calibrate by refilling your tank in known increments and make a few hash marks with an indelible marker right on your in-dash gauge at these intervals. This process will take some time, because you must return the nozzle to the pump and properly ventilate your boat (at least 4 minutes) each time before turning on the key to check the gauge to avoid a potential explosion. If you have questions, comments or would like to share some personal experiences or observations, please contact us.
BoatU.S. Foundation for Boating Safety & Clean Water |
||||||||
