User:Mliu92/sandbox/Hunter's Point gantry crane
| Hunter's Point gantry crane | |
|---|---|
.jpg) | |
| Location | |
| Coordinates | 37°43′11″N 122°21′40″W / 37.719855°N 122.361120°W |
| Details | |
| Opened | 1947 |
| Closed | 1974 |
| Purpose | ship repair, missile testing |
The unnamed Hunters Point gantry crane at the San Francisco Naval Shipyard in the Bayview-Hunters Point neighborhood of San Francisco was the world's largest crane at its completion in 1947. It was designed with sufficient capacity to remove a battleship gun turret intact, but since battleships had become obsolete by the end of World War II, was instead used to refit aircraft carriers and later, to restrain Polaris missile airframe tests. After the Navy withdrew from the shipyard in 1974, the crane has been left as a prominent landmark, where it is easily visible for several miles in each direction.
History[edit]
In 1947 an enormous gantry crane with a 450-long-ton (460 t) capacity was completed at the site by the American Bridge Company. It was the largest crane in the world, and was intended to be used to remove the turrets of battleships so the guns could be quickly replaced while the old set was being refurbished on land. The Hunter's Point crane succeeded YD-171, better known as Herman the German, as the largest crane in America.[1]
Operation Crossroads decontamination[edit]
Following Operation Crossroads, radiologically contaminated ships were initially brought to Bikini for decontamination. As Bikini itself was radiologically contaminated, the ships were moved to Kwajalein Atoll, where the most heavily contaminated ships were scuttled. Preliminary decontamination was conducted at Kwajalein, but a shipyard was needed for more extensive decontamination procedure development, and Hunters Point was chosen in part for its access to academic facilities at Berkeley and Stanford.
Six target vessels were towed to Hunters Point following their participation in Crossroads: ex-Independence, ex-Gasconade, ex-Crittenden, ex-Skate, ex-Skipjack, and ex-Hughes
Operation Skycatch[edit]
In 1959, the crane was used for Operation Skycatch, where Polaris missiles were fired and caught via a string of arresting cables, before being lowered to the ground for testing. Previous versions of the test launched the missiles into San Francisco Bay where they would be later retrieved. Subsequently, the crane was modified for the UGM-73 Poseidon missile test facility by adding a 230-foot (70 m) tall trapezoidal tower was added to the top of the crane, bringing its total height to nearly 500 feet (150 m). This made the crane the tallest man-made structure in San Francisco until the completion of 44 Montgomery in 1967. The structural members were lifted by Marine Boss in 1967.[2]
The crane dominates the landscape in the area as it is easily visible from miles around.[3]
Design[edit]
As completed in 1947, the crane had two independent hoists running along the gantry. The deck of the gantry on which the hoists ran is 182 feet (55 m) above ground level, and the gantry is 730 feet (220 m) long and 142 feet (43 m) wide.[1][4] The deck is built with the ends slightly elevated (by 12 inches (300 mm)) to accommodate sag in the structure under full load. Levelling of the structure is accomplished through hydraulic jacks in the base of each tower.[1]
Each hoist ran on rails on the gantry deck, and each hoist had a main and auxiliary hook. Each main hook had a individual capacity of 245 long tons (249 t) and could travel from 25 feet (7.6 m) below sea level to 160 feet (49 m) above (limited to 130.5 feet (39.8 m) at maximum load).[4] Each auxiliary hook had a capacity of 50 long tons (51 t) and could travel from 35 feet (11 m) below to 191 feet (58 m) above sea level.[4] The two hoists combined weigh 1,593 long tons (1,619 t), and the gantry structure weighs 5,700 long tons (5,800 t).[4] Power for the hoists is supplied through a substation located in one of the tower bases; incoming 11.5kV power is stepped down to 480VAC.[1]
To reach its maximum capacity of 450 long tons (460 t), the two hoists were coupled together and the main hooks were tied to an equalizing beam. The beam itself weighed 40 long tons (41 t) in addition to the combined 5-long-ton (5.1 t) "biggest hook" attached to the middle of the equalizing beam.[1] The maximum load can be lifted to 78.5 feet (23.9 m) above the water.[4]The hoist brakes are designed to slip when the load exceeds 150 to 170% of the rated capacity, to accommodate the rising and falling tides.[1][4]
Gun Mole Pier[edit]
A new mole was built to accommodate the large crane, which is installed at the end of the mole. The mole is 1,700 feet (520 m) long by 405 feet (123 m) wide, and required 3,000,000 cubic yards (2,300,000 m3) of fill. Each end of the crane is cantilevered 162.5 feet (49.5 m) over the water, allowing ships to tie up next to the mole for repairs facilitated by the crane. The concrete foundations for each tower rest on H-piles driven 100 feet (30 m) deep.[1]
The formal name for this mole is the Gun Mole Pier. The Navy has designated this area as Parcel D (sub-parcel D-1) at Hunters Point, and has identified it as radiologically impacted, meaning that it has the potential for, or is known to contain or have contained radioactive contamination, according to a radiological assessment conducted in 2004.[5]: 13, 16, 20 [6]
Gallery[edit]
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The battleship crane dominates the skyline of the Hunters Point area.
References[edit]
- ^ a b c d e f g Stimson Jr., Thomas E. (September 1947). "Spanning the Navy's Mole at Hunter's Point, Calif., is the World's Largest Crane". Popular Mechanics. Vol. 88, no. 3. pp. 124–128, 256. ISSN 0032-4558. Retrieved 28 December 2017.
- ^ Venturino, Marco F. (March–April 1967). "Test facility modifications for Poseidon". The Navy Civil Engineer. 8 (2): 18–19. Retrieved 3 January 2020.
- ^ "Hunters Point Crane". Department of the Navy. Retrieved 11 January 2017.
- ^ a b c d e f "Navy builds world's largest crane" (PDF). All Hands. July 1947. p. 22. Retrieved 28 December 2017.
- ^ Draft Record of Decision for Parcels D-1 and UC-1, Hunters Point Shipyard, San Francisoc, California, February 20, 2009 (PDF) (Report). Department of the Navy, Base Realignment and Closure Program Management Office West. February 20, 2009. Retrieved 2 January 2018.
- ^ Historical Radiological Assessment, Volume II, Use of General Radioactive Materials, 1939-2003, Hunters Point Shipyard (PDF) (Report). United States Department of the Navy. 2004. Retrieved 2 January 2018.
External links[edit]
- "A Rare Look at An Abandoned SF Shipyard". The Bold Italic. 30 September 2014. Retrieved 28 December 2017.
- "Hunters Point Gantry Crane". hunterspointcrane. Retrieved 28 December 2017.
- Carlsson, Chris. "Hunter's Point Naval Shipyard". FoundSF. Retrieved 28 December 2017.
- Short, Steven (28 October 2017). "That huge abandoned structure towering over Hunters Point is a gantry crane from WWII". KALW. Retrieved 28 December 2017.
- "Hunters Point". Accidental Cruiser in the West Indies. Retrieved 28 December 2017.
- "Polaris, Part 2: The Test Programme" (PDF). Flight. 29 July 1960. pp. 147–150. Retrieved 28 December 2017.
- Page 147
- Page 148
- Page 149
- Page 150
- "Briefs on Polaris" (PDF). All Hands. January 1960. p. 28. Retrieved 28 December 2017.
The launcher-test programs have been in progress for some time. Operations Skycatch and Peashooter, at San Francisco Naval Shipyard, are dryland operations to pioneer testing of methods of ejecting the missile. Operations Pop-up and Fishook at San Clemente are tests from a submerged launcher.
- "Navy builds world's largest crane" (PDF). All Hands. July 1947. p. 22. Retrieved 28 December 2017.
- "Engineers catch missiles in "Operation Fishhook"". Electrical Engineering. 78 (10): 1065–1067. October 1959. doi:10.1109/EE.1959.6446003. ISSN 0095-9197.
- Kolcum, Edward H. (25 July 1960). "First Polaris Launched From Submarine". Aviation Week. Vol. 73, no. 4. McGraw-Hill. pp. 32–33. Retrieved 28 December 2017.