BOATBUILDER'S HANDBOOK

Equipment Standards

FEDERAL LAW

183.550 - Fuel tanks: Installation

(a) Each fuel tank must not be integral with any boat structure or mounted on an engine.

 

Each fuel tank intended to be permanently installed, must be made as a separate component and then installed in the boat. Portions of a boat’s structure, i.e. hull surfaces, bulkheads, stringers, floors, decks, frames, etc., may not form part of a fuel tank.

Fuel tanks glued, bonded or foamed-in-place are not considered integral and are therefore acceptable. However, that installation must comply with the applicable portions of this regulation.

Fuel tanks may not be mounted on an engine, except if the engine is part of a portable piece of equipment that is not permanently installed in the boat. If a fuel tank is removed from an engine to be installed in the boat, the installation must comply with the requirements of this standard. Particular attention is directed to the fuel tank vent requirements and the requirements for all openings to be in or at the topmost surface. Many tanks installed on engines have a bottom fuel supply; this fuel tank is not acceptable for installation in a boat.

TO COMPLY WITH THE LAW

  • Each fuel tank is not integral with any boat structure.
  • There is no fuel tank mounted to a permanently installed engine.


 

FEDERAL LAW

183.550 - Fuel tanks: Installation

(b) Each fuel tank must not move at the mounting surface more than one-fourth inch in any direction.


The basic intent of this requirement is to restrict the movement of an installed fuel tank with respect to its mounting surfaces to a minimum amount. No movement would be best. To establish a quantitative test, one-fourth inch in any direction has been selected.

TO COMPLY WITH THE LAW

  • The tank cannot move more than one-fourth inch in any direction, measured at its mounting surface when force is applied in the forward, aft, port, starboard, and vertical directions.

 

FEDERAL LAW

183.550 - Fuel tanks: Installation

(c) Each fuel tank must not support a deck, bulkhead, or other structural component.


A fuel tank is not permitted to be a structural part of a boat to the extent that it provides support for a deck, bulkhead or other boat structure. To determine whether the intent of this regulation is met, the following question must be answered in the affirmative - Is the deck, bulkhead or other structural component properly supported to function as intended with the fuel tank removed? If the answer is no, the tank is providing support that is not acceptable.

It is not intended to prohibit incidental contact of a deck, or hatch with a fuel tank, or to prevent the use of protective covers or panels for fuel tanks. The Coast Guard has also accepted fuel tanks specifically designed to be walked or sat upon: Protective mats or panels resting on the tank top to provide a walking surface have also been accepted by the Coast Guard.

TO COMPLY WITH THE LAW

  • The fuel tank does not support a deck, bulkhead, or other structural component.
  • The structure will not collapse if the tank is removed.

 

FEDERAL LAW

183.550 - Fuel tanks: Installation

(d) Water must drain from the surface of each metallic fuel tank when the boat is in its static floating position.


Metallic fuel tanks must be designed, installed, or a provision made to drain water from the surface when the boat is in its static floating position. (See 183.505 for the definition of static floating position). It is recognized that irregularities in the top surface of a flat-topped fuel tank may be able to retain water by surface tension. The intent of this requirement is to
prevent the entrapment of water which may occur with lipped edges or saucer type tops on fuel tanks.

Foamed-in-place metallic (must be non-ferrous) fuel tanks must be installed with a provision made to prevent water from collecting on top of the metal surface of the fuel tank, such as might occur if the foam formed a basin around fuel tank fittings. An alternate method is to coat the metal fuel tank surface with a barrier coating, other than paint, which will effectively prevent water from contacting the metal surface.

TO COMPLY WITH THE LAW

  • Water will drain from the metallic fuel tank surface when the boat is in Its static floating position, or
  • The tank is effectively coated to prevent water from contacting the metal surface.

 

FEDERAL LAW

183.550 - Fuel tanks: Installation

(e) Each fuel tank support, chock, or strap that is not integral with a metallic fuel tank must be insulated from the tank surface by a non-moisture absorbing material.


Unless a metallic fuel tank has built-in means for supporting and holding the metallic fuel tank in place, a non-moisture absorbing material must be placed between the fuel tank surface and the support, chock or strap. The non-moisture absorbing quality of the material is necessary to prevent localized corrosion of the fuel tank that might occur if moisture was trapped at the support tank interface for prolonged periods of time.

Care should be taken to avoid abrasive combinations of materials even though it is not a mandated requirement of the regulation.

Basically, this requirement provides for the isolation of the metallic fuel tank from a potentially moisture laden support system and also from abrasion by the supports, chocks and straps.
The following table lists some materials that appear to be suitable and some that should
be avoided.

Fuel Tank Isolation Materials
Suitable Unsuitable
Neoprene Cardboard
Teflon Carpeting
High Density Plastics Unpainted Wood
  Felt
  Canvas
  Foams


NOTE:

These lists are not limiting in the materials to be included. They are to establish the intent of the regulatory requirement prohibiting moisture absorbent materials. If possible, the isolation materials should be bonded (glued) to the tank so that moisture (from condensation) cannot be trapped next to the tank.

TO COMPLY WITH THE LAW

  • The fuel tank supports, chocks or straps are integral with the fuel tank or
  • The fuel tank supports, chocks or straps are insulated from the fuel tank by non-moisture absorbing material?

 

FEDERAL LAW

183.550 - Fuel tanks: Installation

(f) Cellular plastic must not be the sole support for a metallic fuel tank.


Non-ferrous metallic fuel tanks may be foamed-in-place if the installation provides support for the fuel tank that is independent of the cellular plastic (foam) (see 183.512(c)). Supports for metallic fuel tanks must be in accordance with 183.550(e). The installation must comply with all applicable sections of 183.550, particularly sections (b), (c) and (d). It is recognized that the foam, upon curing, will assume some of the support for the tank. This is acceptable.

FIGURE 22 - Foamed-in-Place Non-Ferrous Metallic Tank

TO COMPLY WITH THE LAW

If foam is used to install a metallic tank

  • Is the fuel tank made from non-ferrous metal?
  • Is the fuel tank supported independently of the foam?
  • Can water drain from the fuel tank’s surface?
  • Fuel tank supports, chocks and straps are integral with the fuel tank, or
  • Fuel tank supports, chocks and straps are insulated from the fuel tank surface with a non-moisture absorbing material.
  • The fuel tank does not support a deck, bulkhead or other component of boat structure.
  • The fuel tank is restrained from moving more than one-fourth inch in any direction.

 

FEDERAL LAW

183.550 - Fuel tanks: Installation

(g) If cellular plastic is the sole support of a non-metallic fuel tank, the cellular plastic must meet the requirements of Sec.183.516 (b) or (c).


Cellular plastic (foam) may provide the only support for non-metallic fuel tanks. Fiberglass reinforced plastic fuel tanks and other suitable plastics used for fuel tanks may be installed in foam. In order to use foam as the only support for these non-metallic tanks, the foam must meet or exceed the requirements of 183.516(b) for non-polyurethane foam (i.e. compressive strength of at least 60 pounds per square inch at 10 percent deflection or 183.516(c) for polyurethane foam (i.e. density of at least 2.0 pounds per cubic foot). Refer to these sections for further information about the properties required of foam.

TO COMPLY WITH THE LAW

If foam is used as the only support for a non-metallic fuel tank:

  • The foam meets the requirements of 183.516 (b), or (c).
  • The fuel tank is restrained from moving more than one-fourth inch in any direction.
  • The fuel tank does not support a deck, bulkhead or other component of boat structure.

 

 

FEDERAL LAW

183.550 - Fuel tanks: Installation

(h) Each fuel tank labeled under Sec. 183.514(b)(8) for installation aft of the boat’s half length must be installed with its center of gravity aft of the boat’s half length.


Fuel tanks which are labeled "Must be installed aft of the boat’s half length" in accordance with 183.514(b)(8) are to be installed with the fuel tank’s center of gravity toward the stern of the mid-length of the boat. These fuel tanks have been qualified at a lower strength criteria than those fuel tanks capable of installation at any location in a boat. The shock loading or impacts felt by boats are more severe in the forward portion of a boat than in the aft section.

Fuel tanks that are meant for installation at any location in a boat shall be tested at 25g vertical accelerations in accordance with 183.584(e)(1), or they must be tested in accordance with either 183.586, or both 183.586 and 183.588, depending on their capacity. Fuel tanks meant only for installation aft of the boat’s half length may be tested at 15g accelerations in accordance with 183.584(e)(2) if their capacity is less than 25 gallons. Table III shows the strength test for fuel tanks according to the tank’s capacity and intended location in a boat.

TABLE III - Strength Tests for Fuel Tanks

TO COMPLY WITH THE LAW

  • Is the fuel tank marked "Must be installed aft of the boat’s half length"?
  • If so marked, is the tank’s center of gravity located aft of the boat’s half length?


 


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