Fuel Systems - General


183.501 - Applicability

(a) This subpart applies to all boats that have gasoline engines, except outboard engines, for electrical generation, mechanical power, or propulsion.

FIGURE 1 - Applicability



183.505 - Definitions

As used in this subpart:

Flame arrestor means a device or assembly that prevents passage of flame through a fuel vent.

A flame arrestor for a fuel tank may be a specially designed fitting with flame arresting elements, such as screens, or the vent tubing may itself be effective. Air flows in both directions in the fuel tank vent. Outside air goes into the tank to equalize the pressure when gasoline is used in the engine and fuel vapor-laden air flows out of the tank through the vent when the tank is being filled. Ambient temperature changes also cause air flow in both directions. If the fuel vapor-laden air is ignited outside the fuel tank fittings or discharge point, the flame arrestor is to prevent the flame from being propagated through the fuel tank vent into the fuel tank.

If it is intended to qualify a vent system without a specially designed fitting containing flame arresting elements, it is recommended that extreme caution be exercised to assure safe conduct of any qualifying test.




183.505 - Definitions

As used in this subpart :

Fuel system means the entire assembly of the fuel fill, vent, tank, and distribution components, including pumps, valves, strainers, carburetors and filters.

A typical fuel system is diagrammed in Figure 2. Other fuel systems may contain more or fewer components, and may be of other materials as permitted under these conditions. Two or more engines in a boat will necessitate a more complicated system, which may include a number of fuel tanks with possible provisions for interconnection. Fuel transfer pumps may also be included in the fuel system.

FIGURE 2 - A Typical Fuel System



183.505 - Definitions

As used in this subpart:

Static floating position means the attitude in which a boat floats in calm water, with each fuel tank filled to its rated capacity, but with no person or item of portable equipment on board.

This is to establish a standard measurement condition. It is not related to freeboard or other safety considerations, but is an attitude of the boat which can be obtained on a repeatable basis for use in testing certain criteria of the regulation. The requirements which will be checked with the boat in a "static floating position" are:

  1. Water accumulation on the top of the fuel tank (183.550)
  2. Anti-siphon protection (183.568)
  3. 5-ounce fuel leakage (183.558)
  4. Fuel fill overflow (183.564)

FIGURE 3 - Static Floating Position

Examples of portable equipment:

  • Mattresses
  • Portable fire extinguishers, except brackets
  • Lines
  • Fenders
  • Personal flotation devices
  • Chairs
  • Tables
  • Anchors and chains

A boat builder should record what equipment the test sample has on board during the test in order that a compliance test may be conducted in the same manner.



183.507 - General

Each fuel system component on a boat to which this subpart applies must meet the requirements of this subpart unless the component is part of an outboard engine or is part of portable equipment.

The boat manufacturer, not the manufacturer of each component, is required to certify each boat as complying with this regulation. Component parts of outboard engines and portable equipment, such as a self-contained gasoline engine generator unit, are not covered by these regulations.

The Equipment Standards of this regulation appear to impose requirements, and consequently certification responsibilities, on component manufacturers including inboard engine manufacturers. This is not the case. The boat manufacturer is responsible under these regulations and must certify compliance. Purchase orders can stipulate that component manufacturers provide affidavits of compliance which a boat manufacturer may choose to recognize as supporting evidence in certifying the entire fuel system.


Previous  |  Next


Media and Marketing Materials

Members of the press, boating safety specialists and advocates, and the general public are invited to utilize any and all of the media and marketing materials in this section.


Photo Library

The U.S. Coast Guard has provided the Image Library as a resource tool for boating safety specialists, advocates and the general public.


Video Library

The U.S. Coast Guard has provided the Video Library as a resource tool for boating safety specialists, advocates and the general public.




   safe a float