Frequently Asked Questions
As a service to our members, ABYC is introducing a FAQ column. We encourage you to submit any questions for which it would be helpful to have the ABYC response. Please send comments to jramsey@abycinc.org or mail to FAQs, ABYC, 3069 Solomons Island Road, Edgewater, MD 21037. We look forward to hearing from you.
Spring 2003
Q. Did ABYC make a rule change that changed the color of the DC negative wire from BLACK to YELLOW?
A. No. Included in E-9 DC Electrical Systems on Boats since 1996 has been the OPTION of using YELLOW as an alternate color for the DC negative lead. If there is an AC system installed on the boat then the BLACK wire can also be the ungrounded (hot) current carrying conductor. An increasing number of builders are using YELLOW as the alternative to black in the DC conductor to avoid confusion. Confusion, I might add, that could result in a very bad situation when the AC hot is confused with the DC negative.
Q. ABYC E-10 requires that I have a 12” “Dielectric shield” above my battery for the purposes of gassing. I understand this requirement when installing traditional “Lead Acid” type batteries, however, I am installing gel-type batteries and do not see the need for this spacing.
A. First, E-10 does not differentiate between traditional (lead-acid) and newer types of batteries (gel) that minimize or eliminate hydrogen gassing. Keep in mind that a battery is not permanent. At some point in time, the unit will have to be replaced. Generally these batteries are replaced with what the owner can afford or what the owner finds is available at the time. The suggested method of installation found in E-10 takes into account this common situation. Since hydrogen gassing can affect most materials used in component construction (e.g. aluminum cases on chargers/inverters, fuel lines) the standard calls for the 12” of dielectric shielding.
Fall 2002
Q. Are devices installed in a diesel engine compartment required to be "Ignition protected?"
A. No. E-8, AC Electrical systems on boats and E-9, DC Electrical systems on boats both describe the need for ignition protection in spaces containing gasoline powered machinery, gas tanks, fittings or other connections between components of a gasoline system. Written below this requirement is an exception for boats using diesel as the only fuel source. For example, you may install a non-ignition protected device (any electrical component that is not labeled "Ignition Protected") in an engine compartment containing a diesel engine, however, add a gas generator set to that same compartment and then all electrical items must be ignition protected.
Q. Is there anyway that I can take a look at your standards book without buying it?
A. Yes! As BoatU.S. stores are renovated and remodeled, copies of the ABYC Standards manual are being displayed. To find out if the ABYC Standards are available at your local BoatU.S. store, give them a call.
Q. While rewiring my boat, a guy at the dock told me to make sure that I meet the CFR. What is it and how do I meet it?
A. The CFR are the Code of Federal Regulations. Title 33 & some of Title 46 CFR requirements pertain to recreational boats. As far as complying with the CFR, NO WORRIES!! If you meet ABYC standards you meet or EXCEED the requirements of the CFR.
Summer 2002
Q. Can a diesel fuel tank have openings below the top of the tank?
A. Yes; ABYC Standard H-33, Diesel Fuel Systems is silent on the issue of location of diesel fuel tank openings and therefore does not prohibit openings below the top of the tank.
Q. Is a fixed fire extinguishing system required in the engine compartment of an inboard boat?
A. ABYC Standard A-4, Fire Fighting Equipment requires that inboard and sterndrive boats (both gasoline-fueled as well as diesel-fueled) with engine compartments shall have either a fixed fire extinguishing system installed in the machinery space or provisions for discharging a suitably sized clean agent portable fire extinguisher directly into the space immediately surrounding the engine without opening the primary access. Requirements for the discharge port, as well as labeling requirements, are given in the standard.
Q. Are there engine compartment ventilation requirements for diesel-fueled boats?
A. ABYC Standard H-32, Ventilation Of Boats Using Diesel Fuel states "power or natural ventilation is not required on a diesel boat, but may be used to control compartment temperature." The standard also provides guidance on other ventilation considerations such as supplying necessary combustion air, venting hydrogen gas from batteries when appropriate, and removing the discharge from fixed gaseous fire extinguishing systems.
Spring 2002
Diesel vs. Gasoline Engines
Q. Why does a diesel engine operate more economically than a gasoline engine?
A. There are two basic reasons why a diesel engine operates so much more economically than a gasoline engine. First we must take a look at the fuels themselves. Diesel fuel is much heavier than gasoline… with densities of around 0.85 for diesel and about 0.74 for gasoline. The higher density of the fuel the higher the heating value. This translates to a net heating value of about 130,000 BTU per gallon for diesel, and about 115,000 BTU per gallon for gasoline. Therefore, diesel has about 12% more energy per gallon.
Next, we look at how the fuel is combined with air and ignited. There are some fundamental differences:
A gasoline engine mixes the ambient air and fuel before drawing it into the cylinders. The diesel forces the air (turbo charger) into the cylinder, compresses it, and then injects the fuel into the cylinder. The gasoline engine ignites the fuel/air mixture with a single spark. The resulting flame front grows during the compression and power cycles. The diesel engine uses the high temperature of compression to ignite the injected fuel. This method causes combustion to occur over a much larger surface of the fuel and providing more complete combustion. The charge of fuel can be controlled to generate more power during the power stroke, and for a longer duration.
Due to these differences, a diesel engine can achieve thermal efficiencies above 50% while a gasoline engine is only about 30% to 33% efficient
Winter 2001
Q. Is a lightning protection system required to be installed in a boat?
A. No, but if one is installed it should comply with E-4, Lightning Protection. This standard provides guidance on the proper size of conductors, the types of components to be connected to the system, and the method of discharging the lightning currents into the water.
Q. Should the bilge pump float switch be installed in the positive or negative conductor?
A. The positive conductor. The placement of the switch takes into consideration the possibility of stray current corrosion. With two electrical components in the bilge water, it is best to minimize the number of components that carry the voltage continuously. With the switch in the positive conductor, the pump only sees the voltage when the switch is activated. This helps reduce the effects of stray current corrosion should the pump become damaged.
Q. What are the limitations for the use of stainless steel in fuel tank applications?
A. Stainless steel can be used for both gasoline and diesel fuel tanks. However, for gasoline tanks, the tank cannot be any larger than 20 gallons and it must be cylindrical with domed ends. There are no restrictions on size for diesel tanks.
Fall 2001
Q. Can welding cable be used on boats?
A. Welding cable is often used for battery cables on boats. However, the welding cable’s insulation must be oil and water-resistant. Cable that is not oil and water resistant may become impregnated with the water or oil and reduce the insulation’s effectiveness. ABYC E-9.15.2 covers the requirements for the construction of cables and conductors.
Q. Is it necessary to provide separate ventilation openings for combustion air and natural ventilation?
A. No. If it was determined that 10 square inches of intake and 10 square inches of exhaust opening was necessary for natural ventilation (20 square inches total), and 24 square inches was needed for combustion air, two 12 square inch openings would satisfy both requirements.
Q. Why is the LPG system pressure gage installed on the cylinder (high-pressure) side of the pressure regulator and not on the appliance (low-pressure) side?
A. The gage is installed in the system to provide a quick and easy way to test the LPG supply system for leakage. With the gage in the high-pressure section of the supply system, a leak anywhere between the tank valve and appliance valves will be detectable more readily than if the gage were in the low-pressure section. A supply system leak test should be conducted every time the cylinder supply valve is opened for use, and after any event that might effect the integrity of the system, such as grounding, fire, or collision. The leak test is conducted by pressurizing and then isolating the supply system. With the supply system pressurized, the pressure gage reading should remain constant for at least three minutes. Any drop in pressure would indicate a leak somewhere in the supply system. The requirements for the gage and leak test are given in ABYC A-1.5.1, A-1.5.2, and A-1.10.3.1.
Summer 2001
Q. Is the 12 VDC negative conductor suppose to be black or yellow?
A. For boats sold in the United States either color can be used. Yellow was added as an option to allow the differentiation between the AC systems line conductor and the DC negative on boats with both AC and DC electrical systems. Even if the boat does not have an AC electrical system, yellow may be used for the DC negative conductor.
Q. Can a fuel pump be installed in, or near, the gasoline fuel tank to help eliminate vapor-lock?
A. Both ABYC H-24, Gasoline Fuel Systems, and the Code of Federal Regulations do, within certain parameters, permit the use of a remote fuel pump. The parameters are: the pump must be located within 12 inches of the engine that it supplies, and the hose from the pump output to the engine cannot exceed 48 inches. The objective of these requirements is to limit the amount of pressurized fuel hose in the boat. Any pressurized fuel hose that develops a leak can cause a significant fire and explosion hazard by spraying fuel into the compartment. The USCG has provided a grant of exemption to some boat manufacturers to permit the installation of the fuel pump in the tank. These exemptions are granted on a case by case basis and are based on a demonstrated ability of the system design to provide at least an equivalent level of safety. These designs may include a hose-within-a-hose design where the outer hose captures any fuel that may leak from the inner pressurized delivery hose, and a sensor causes an alarm to indicate that there is an inner hose leak.
|
