Maintaining a Battleship in Reserve
The nuts and bolts of America's ship preservation program.
Copyright 2002
The protocols for taking care of IOWA as a mobilization asset in the "mothball
fleet" have long been written. But as you can imagine, taking care of 46,000
plus t
ons of steel requires a considerable inventory of skills and talent. Rest
assured that in the San Francisco Bay Area, IOWA has benefited from the care of some of our
nation's most experienced hands, those of the Maritime Administration ("MARAD").
In the region, more than one hundred ships are preserved by the Maritime
Administration with the help of private industry in Suisun
Bay, just north of San Francisco and merely miles away from Vallejo. Further, the Naval Reserve
community offers a priceless reservoir of skilled manpower. The region also
boasts substantial facilities. San Francisco Drydock Inc. has the capability to
drydock IOWA. At nearby Hunters Point, there is even a functional regunning,
heavy lift crane that was specifically designed for 'Iowa'-class battleships.
Two of the most important maintenance functions in caring for a ship in "cold iron" or reserve status are the establishment of a dehumidification system to prevent internal areas from rusting and the use a cathodic protection system to preserve the hull. Otherwise, the combined effects of unchecked internal rusting and metallurgical degradation would soon mortally wound this great ship.
DEHUMIDIFICATION: Dehumidification ("DH") efforts prevent a ship from rusting internally. Rust (ferrous oxide) is formed by the chemical reaction of iron and oxygen. The combination of iron with oxygen results in the deterioration of the surface of the metal. In chemistry, rust is the result of the corrosion of iron, by way of oxidation in the presence of water. As air can contain water, it is necessary to control humidity within a ship to keep water away from steel. The "dew point" is the point at which the water vapor condenses out of the air. This phenomena also happens inside a vessel when air temperature is lowered by the hull structure being cooled by surrounding cold water. This "sweating" causes rust to form on the exposed steel surfaces of structure and machinery. A dehumidifier controls this phenomena by cooling the air that passes through it and collecting the water that condenses out and second, it warms up the air so that it is above the dew point. IOWA has a number of dehumidifiers and the vessel is hermetically sealed to keep dehumidified, dry air inside. This dry, warm air is continuously circulated around machinery and equipment to prevent rust. Indeed, in machinery spaces, equipment may be partially disassembled, while entry hatches to fuel and other tanks opened to benefit from the preservative effects of DH operations. The dry, warm air is circulated through these spaces and the entire ship by means of plastic ventilation pipes that snake their way throughout IOWA.
The year is 1997. Left:HSMPS Committee Members and dehumidifier in Captain's Cabin. Right: Philadelphia Yard maintenance crew and Committee Members gather on main deck, amidships for a photo shot, after a two-day inspection when IOWA was in donation status.
CATHODIC PROTECTION: Cathodic protection ("CP") is one of the most effective methods for mitigating corrosion of steel structures in soil and water. Corrosion of ferrous metal is a natural process in which metal returns to its native ore. Changing anodic and cathodic areas develop on metal for a number of metallurgical or environmental reasons. Corrosion occurs at the anodic areas. Cathodic protection mitigates corrosion through the use of a low voltage DC current that polarizes the hull to a potential equal to or more negative than its most active anode. IOWA's hull will be protected by an external electro-catalytic protection system, that is suspended around the ship. The battleship at present has a sacrificial zinc anode system, in which the zinc below the waterline sacrifices itself to protect the hull. By augmenting the protection provided by the zinc anodes with a suspended cathodic protection system, it is hoped to extend the service life of the zinc anodes while establishing a more effective CP network
Both dehumidification efforts and cathodic protection routines require skill and hard work. For instance, if the voltage in a cathodic protection system is wrong, it can destroy a hull rather than preserve it. Meanwhile, dehumidification systems require an enormous amount of work. The ship must be sealed to the outside world. Portholes and vents to the weather decks must be closed and, with the most dehumidifiers, miles of plastic ventilation pipes established internally circulate dehumidified air to all regions of the ship. To be effective, IOWA's fuel tanks, machinery and spaces must be opened and vented to the dry air. Nor does the task end here.
DECKS: IOWA's teak weather decks will require ongoing maintenance or replacement. This means carpentry and lots of elbow grease. Damaged planking must be removed and new wood inserted. Any rust damage to the steel plate underneath the wood needs to be addressed. This requires scraping and priming. Caulking for the teak decks must be inspected and also repaired. Decks should be sealed against the effects of weather. Drains will need to be cleaned so rain water can drain from weather decks.
PAINTING: As paint weathers, flaking may occur and external areas will need to be repainted. Inside IOWA, paint flaking will also need to be addressed. Paint removal will mandate precautions, as some areas may contain lead paint. Outside, netting will be used so that when scraping or sand blasting surfaces, loose paint does not fall into the Bay to pose an environmental problem.
CLEANUP: Weather decks need to be clean of debris.
These very general descriptions should help provide some idea of the efforts that will be expended on maintaining IOWA. Much more detail, down to manpower requirements and even electrical bills have been projected by Historic Ships Memorial at Pacific Square and delivered to the Department of the Navy. Can IOWA be maintained here in the Bay Area? The answer is a definitive "yes". It was indeed a testament to the Bay Area, when senior Navy officers in Washington noted the excellence in ship care demonstrated by MARAD and Bay Area workmen, and approved IOWA's relocation to Suisun Bay.