Passaic class monitor

The ''Passaic''-class ironclad monitors of the U.S. Navy saw service in the U.S. Civil War and the Spanish–American War. The class was an improved version of equipped with a 15-inch Dahlgren gun in place of one of the 11-inch guns.

Design

Naval architect and engineer John Ericsson designed the ''Passaic''-class warships, drawing upon lessons learned from the first , which he also designed. The ''Passaic'' monitors were larger than the original ''Monitor'' and had their pilothouses atop the turret, rather than near the bow. This allowed a wider field of view and easier communications between captain, pilot and crew. The shape of the hull was an improvement; a fuller and rounder lower hull, far more boat-like than that of the ''Monitor'', and with a less pronounced overhang. The ''Passaic'' class featured an funnel and improved ventilation. In combination, the significant hydrodynamic refinements and improved draught to the boilers resulted in a one-knot speed increase over the prototype monitor, despite the ''Passaic'' having a lower Power-to-weight ratio, specific power than ''Monitor'' (''Passaic'' being almost 400 tons heavier and yet with the same 320ihp-rated machinery).

Having observed the new 15-inch Rodman cannon in fortifications and disappointed with the performance of the 11-inch Dahlgren versus , Assistant Secretary of the Navy Gustavus Fox required the new monitors to be equipped with at least one gun of 15-inch caliber, resulting in rush production of a new 15-inch Dahlgren. The turret was in diameter inside with the gun mounted flush because the muzzle diameter was too large for the turret opening. The large volume of propellant gases released inside the turret required the addition of a "smoke box" at the muzzle in the interior of the turret.Olmstead, ''The Big Guns'', p. 94 As a result, the 15 in gunners could not see their targets and had to aim with the or guns. ''Lehigh'' had her 11-inch smoothbore replaced with an 8-inch Parrott rifle. ''Passaic'' also had this modification by July 1863, and, eventually, all surviving members of this class had an additional 15-inch smoothbore added.
Later improvements included an additional 50 tons of deck plating over the magazines and machinery spaces as well as rings fitted around the turret and pilot houses to prevent their pivoting machinery from being jammed by shot.

Ships in class

Warships of ''Passaic'' class included:

* USS Passaic (1862), ''Passaic''
* USS Montauk (1862), ''Montauk''
* USS Nahant (1862), ''Nahant''
* USS Patapsco (1862), ''Patapsco''
* USS Weehawken (1862), ''Weehawken''
* USS Sangamon (1862), ''Sangamon''
* USS Catskill (1862), ''Catskill''
* USS Nantucket (1862), ''Nantucket''
* USS Lehigh (1863), ''Lehigh''
* USS Camanche (1864), ''Camanche''

The first ship of the class was named for the city of Passaic, New Jersey.

See also

* , an Imperial Russian Navy monitor type built to the plans of the American ''Passaic'' class.

Notes

References

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{{Union ironclads

Monitor classes
Passaic-class monitors,