"A bow replacement on an operational hull is unique and has never been accomplished before," said Pat Dolan, spokeswoman for Naval Sea Systems Command in Washington, D.C.

The operation is scheduled to begin in November and will take nearly two years to complete but is expected to save taxpayers tens of millions of dollars.

The Honolulu is on its final deployment. The San Francisco has been in Bremerton since September, awaiting permanent repairs. Both are Los Angeles-class submarines.

Replacing the bow is expected to cost $79 million, Dolan told the Kitsap Sun newspaper, well below the $170 million that would have been required to refuel the Honolulu's nuclear reactor.

The San Francisco is four years older than the Honolulu but was refueled and overhauled in 2000-02.

The retiring Honolulu would come to Bremerton for decommissioning even without the plan to reuse its bow because the shipyard houses the Navy's nuclear ship and submarine recycling program.

Rep. Norm Dicks, D-Wash., inserted language into the 2007 defense spending bill to provide funds for the San Francisco repairs.

The San Francisco's bow was severely damaged when it hit an undersea mountain near Guam in January 2005. One sailor died and nearly 100 were injured.

Otherwise, the San Francisco's systems remained functional, Dolan said. It returned to Guam under its own power and underwent temporary repairs for the trip to Bremerton.

The submarine's commanding officer, Cmdr. Kevin Mooney, was relieved of his position following the crash. His superior officer wrote, however, that "the crew's post-grounding response under his direct leadership was commendable and enabled (the subs) recovery and safe return to port."