s1205.pdf
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- FY27 NOAA Ship Gordon Gunter Drydock REFERENCES Federal contract opportunity
- Solicitation number
- 1305M226Q0144REF
About this file
This is a NOAA Standard Specification document for zinc protectors dated August 1994.
The specification establishes requirements for hull zinc installation on steel, wood, and aluminum hull ships. Standard zinc protectors measure 6" x 12" x 1¼" and must comply with MIL-A-1801 specifications with cast-in straps. For single screw ships, the total number of zincs installed shall equal the total underwater metallic area multiplied by 0.001; for twin screw ships, this factor increases to 0.0015. Zinc attachment locations are governed by ship type: on steel ships, zincs attach to hull plating close to and symmetrically about propellers in locations that remain totally immersed, with minimum 24-inch spacing between adjacent zincs and prohibition against attachment to propeller shafts, rudders, skegs, stern tubes, or strut arms. On wood ships, one 6" x 12" zinc is required for every 25 square feet of underwater metal area, with minimum requirements of one zinc per rudder face, strut face, and sea chest. For smaller areas, zincs may be cut to 6" x 6" or 3" x 12" sizes. Attachment methods include welding (preferred) or stud attachment with specified locking mechanisms. All zinc protectors must install in fore and aft lines where practicable and withstand bending to a 15-inch radius while hot (200°F to 400°F). The specification includes a materials list referencing zinc per MIL-A-18001, galvanized steel components, bronze lag bolts, and brass straps.
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Text version
August, 1994
NOAA Standard Specification - S1205
ZINC PROTECTORS
Hull zincs (standard size 6"x12"x1¼") shall be installed on all steel, wood and aluminum hull ships. High purity zincs with cast-in strap should comply with specifications MIL-A-1801 and be attached in accordance with Figure 1.
The total number of 6"x12"x1¼" zincs installed on a single screw ship should equal the total underwater metallic area multiplied by 0.001; on twin screw ships this factor should be 0.0015.
Hull Plating - Steel Ships:
Zincs should be attached to the hull plating as close as practicable to and symmetrically about the propellers. Zincs should be attached in locations that will always be totally immersed. In addition, zincs shall not be attached to propeller shafts, rudder, skegs, stern tubes, strut arms or strut barrels.
If practicable, the distance between adjacent zincs should not be less than 24 inches.
Wood Ships:
On wood ships, one 6"x12" zinc should be used for every 25 square feet of underwater metal area; however, a minimum of one zinc per rudder face, strut face and sea chest should be fitted.
Skegs where fitted and in metallic contract with a protected fitting, should be considered a part of the fitting.
For areas too small for a 6"x12" zinc, this size may be cut in half to 6"x6" or 3"x12" zincs may be used. Zinc shall be installed as shown on Figure I. On rudders, the zincs should be located outside of the propeller flow insofar as practicable.
Zincs for struts should not be attached to the strut arm.
Metallic contact may be made at the strut palm.
Straps of the zincs but NOT THE ZINC should be painted the same as the hull.
General Notes for Figure I
1. Install all zinc protectors in a fore and aft line where practicable.
2. Stud attachment for cast-in strap protectors are approved;
however, welding is preferred. When attachment is by studs, holes drilled in strap as shown. When welding straps to structure, ends may be cut off to within ¼" of bend.
Zinc Protectors S1205
3. After attachment, nuts shall be prevented from loosening by placing a cotter pin through the nut and stud, splitting the stud down its longitudinal axis, and peening over the stud, or by tack welding the nut in cast-in strap.
4. Where zincs are installed to the hull of a wood ship to protect the adjacent metallic structure, contact between the strap of the zinc and the protected structure may be made by welding or through the lag screw as shown in Detail A.
5. The protector will be able to withstand bending to a 15" radius on either axis. The protector shall be bent using a pyramidal roll, while hot (between 200/ - 400/F).
List of Materials for Figure I
Pc.
No. Name of Piece Material Specification Remarks
1 Plate Zinc Protector Zinc MIL-A-18001 CL II, Type ZPN 2 Welding Stud, ½"-13NC-2 Steel Commercial Length to Suit 3 Nut, ½"-13NC-3 Steel Gal.Commercial 4 Lock Washer Steel Gal.Commercial 5 Cast-in Strap Protector Zinc MIL-A-18001 Cl I, Type ZHS 7 Stud, ½"-13NC-3 & 5 Steel Gal.Commercial Length to Suit 8 Zinc Oxide Paste Zinc Oxide 10 Cast-in Strap Protector Zinc MIL-A-18001 Cl I, Type ZHS 11 Lag Bolt, d" diameter Bronze Commercial Length to suit 12 Strap, 1¼"x3/16" Brass Commercial Length to suit
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