It was a fortunate move, as the Fulton's company trials turned up numerous deficiencies that needed to be corrected.

[4] Although Fulton eventually did quite well on trials, proving the capabilities of the Plungers, there were no approved appropriations from the Navy to purchase her so she was sold to Russia, and renamed Som.

[5][6] Holland's emphasis was on optimizing underwater performance, and thus the boats had very little superstructure topside and a very small conning tower.

One man, a very busy Commanding Officer, stood on a raised platform amidships with his head up inside the conning tower so he could see out of the small deadlight windows there.

Several wheels and control levers were within reach of this station, with the Commanding Officer acting as both a helmsman and a diving plane operator.

Ventilation of the gasoline engine was poor, the main switchboard needed to be relocated, the 30-foot depth gauge was inadequate, the torpedo tube muzzle door was awkward to use, and periscopes were highly desired.

Most notably, the lack of superstructure and the short conning tower made these boats prone to flooding when surfaced in even a moderate sea state.

A modification program was drawn up and approved by the Navy and starting in January, 1905 the boats were taken in hand for the needed work.

[8] Eventually most of the boats were fitted with two fixed height periscopes, with a taller conning tower that had a large fairwater built around it.

A small, metal framework and canvas bridge structure could be erected topside for extended surface transits.

[12] However, the rapidly advancing military technology of the early 20th century quickly made these boats obsolescent, and by the end of World War I they were completely outmoded.