SRF-JRMC Conducts Successful USS Blue Ridge Inclining Test
Story and photo by Keiichi Adachi, CFAY Public Affairs



USS Blue Ridge (LCC 19) heels slightly to port in dry dock after SRF-JRMC precisely positioned weights during her inclining experiment. Environmental conditions were near perfect during the execution of the inclining experiment.

重心検査実行中にSRF-JRMC従業員が正確に荷重を設置し、ドック内のUSSブルーリッジは左舷に少し 傾く。検査実行中の環境状況はほとんど完全なものであった。



SRF-JRMC workers ensure weights are correctly placed at their designated locations during Blue Ridge’s inclining experiment. Photo courtesy of USS Blue Ridge Public Affairs Office

重心検査中、ブルーリッジ艦船上でSRF-JRMC従業員は荷重が指定 の箇所に正確に置かれていることを確認する。 写真提供：ブルーリッジ広報室



A USS Blue Ridge Sailor observes one of the locations used to measure inclining experiment data. Pendulums and an inclinometer measure the angle of heel caused by planned weight movements. Photo courtesy of USS Blue Ridge Public Affairs Office

ブルーリッジの乗組員が重心検査箇所を見守る。振り子と重心計は 計画された荷重の移動により生じた傾きの角度を測る。 写真提供：ブルーリッジ広報室

A collective team effort by U.S. Naval Ship Repair Facility and Japan Regional Maintenance Center (SRF-JRMC), Puget Sound Naval Shipyard & Intermediate Maintenance Facility (PSNS&IMF), and USS Blue Ridge (LCC 19) led to the successful completion of an inclining experiment on Blue Ridge Jan. 18. The day before, the combined docking team of SRF-JRMC shop personnel and Commander Fleet Activities Yokosuka’s Port Operations positioned Blue Ridge safely into dry dock despite windy conditions.

Keiichi Machida, an SRF-JRMC Japanese Ship Superintendent who has worked at SRF-JRMC more than 15 years, noted that Blue Ridge is 41 years old. “This is the 2nd time I observed an inclining experiment for Blue Ridge. I am not sure of exact number of times she has undergone past inclining experiments. I would say at least two or three have been conducted before.”

An Inclining Experiment determines ship displacement, ship’s center of gravity, and subsequently, the ship’s stability. It is the only accurate method available after a ship has undergone weight-changing modifications. Each inclining experiment updates stability calculations and revises the ship’s damage control book. They also determine if corrective action to restore stability is necessary and form the basis for future calculations.

“To conduct the experiment successfully, Blue Ridge needed to be in still water, as provided by a flooded dry dock, and remain steady with no wind,” said SRF-JRMC Docking Officer Lt. Cmdr. Mark Schuchmann. According to Lt. Jay Ponton, Blue Ridge Ship Superintendent, “Inclining experiments are recommended whenever any major work conducted on a ship alters the fundamental weight distribution, such as adding superstructure or a heavier topside weapon system.

Inclining tests calculate any shift in the center of gravity due to the alterations and any subsequent effect on the ship’s stability.” Naval Sea Systems Command (NAVSEA) orders inclining experiments on certain ships when center of gravity shifts are suspected to determine if the ship’s stability has been adversely affected. Schuchmann said, “The PSNS&IMF inclining experiment team provided oversight.

The process began by surveying Blue Ridge to determine her present condition. During the experiment, SRF-JRMC workers used forklifts to precisely position 160,000 pounds of weights to generate the data needed to calculate the vertical center of gravity. Placing the weights in designated positions, with the exact weight and distance known, was critical to the testing. Moving the weights induced heel. Team members then measured and recorded the angle of heel verses the weight movement for plotting and calculations.”

Inclining measurements usually require six or seven hours, but the entire inclining experiment process lasts four to eight days.

The inclining experiment was successful, yielding good results, according to Jack Perkins, Blue Ridge port engineer. Ponton said that the key to success of the inclining experiment was excellent coordination and communication between all the key players from PSNS&IMF, SRF-JRMC, and ship’s force. “This communication began last October and was essential to maintaining the timely, safe and effective testing on Blue Ridge. The data obtained from the inclining experiments will be used to develop a full incline report and to recommend any changes required to improve stability.”

“Our preparations for Blue Ridge’s inclining experiment went very well. The PSNS&IMF, SRF-JRMC and ship’s force team knew exactly what was expected and what needed to be done. Everyone was very helpful in preparing for the testing.

We had already designated where the weights had to be, and everything was ready before we started the experiment. All SRF-JRMC employees were cooperative and responsive throughout the survey evolution, expertly completing all their tasks,” said Schuchmann.