46 CFR 160.049-4 - Construction and workmanship.
(a) General. This specification covers buoyant cushions of the box type filled with unicellular plastic foam buoyant material. Such cushions consist essentially of a buoyant insert contained in an outer cover fitted with grab straps. The primary purpose of such cushions is to provide buoyancy to aid a person in keeping afloat in the water. Buoyant cushions providing less than 20 pounds buoyancy or less than 2 inches in thickness will not be acceptable.
(b) Cover. One piece of material each for the top and bottom shall be stitched together to form the cover except that piecing of the cover material will be allowed provided it is for decorative purposes only. Gusset or boxing materials shall be of not more than two pieces. If more than one piece of material is used for the top, bottom, boxing or gusset, they shall be attached by a double row of stitching of the type shown in Federal Standard No. 751, for Seam types SSw-2 or LSb-2. The top and bottom may be of any of the materials permitted for the cover, but the boxing or gusset shall be a cotton fabric as specified by § 160.049-3(b)(1) or other equivalent material of a porous nature. Nonporous materials will not be permitted for the boxing or gusset, but coated upholstery cloth specified by § 160.049-3(c)(2), perforated to permit adequate draining and drying will be acceptable.
(c) Buoyant material. A buoyant insert for a buoyant cushion must comply with the requirements in paragraph (c) (1) and (2) of this section and may be:
(1) Molded in one piece; or
(2) Built up from sheet material if it is formed from:
(i) Three pieces or less in each layer, cemented together with an all-purpose vinyl adhesive such as or equivalent to U.S. Rubber No. M-6256 or Minnesota Mining No. EC-870 and No. EC-1070;
(ii) Three layers or less that may be cemented; and
(iii) Staggered butts and seams of adjacent layers.
(d) Grab Straps. Grab straps shall be attached as shown on Dwg. No. 160,049-1 and shall finish 20 inches long and 1 inch wide at opposite ends. The grab straps, if formed from cover material shall be folded and stitched together so as to produce a double thickness with raw edges turned under. Other means will be given special consideration.
(e) Seams and stitching. Seams shall be constructed with not less than a 3/8-inch border between the seam and the edge of the cover materials. All stitching shall be a lock stitch, 7 to 9 stitches per inch, except as follows: Chain stitching 6 to 8 stitches per inch with 20/4 thread on top and 40/3 thread on the bottom, will be acceptable in constructing grab straps.
(f) Workmanship. All cushions shall be of first class workmanship and shall be free from defects materially affecting their appearance or serviceability. Cushions classified as “seconds” or “irregular” will not be acceptable under this specification.