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USS Sonoma (Tug No. 12) on builder's trials circa August 1912
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Class:        SONOMA (AT-12)
Design:        Navy AT-12
Displacement (tons):        883 gross, 1,120 norm.
Dimensions (feet):        185.2' oa, 175.0' pp x 34.0' m, 35.5' e x 12.5' mn
Original Armament:        None
Later armaments:        1-3"/50AA (1917/18: both); 1-3"/50SP 1-3"/50AA (1919: both);
none (1920: AT-12, 1941: AT-13);
4-20mm (1943-44: both)
Complement:        60 (1929)
Speed (kts.):        13
Propulsion (HP):        1,596
Machinery:        Vert. triple expansion, 1 screw. 1517 IHP in AT-13

AT Name Ord. Builder Keel Launch Commiss.
12 SONOMA 28 Jul 11 New York SB 7 Nov 11 11 May 12 6 Sep 12
13 ONTARIO 28 Jul 11 New York SB 23 Nov 11 11 Apr 12 4 Sep 12

AT Name Decomm. Strike Disposal Fate MA Sale
12 SONOMA -- 27 Nov 44 24 Oct 44 Lost --
13 ONTARIO 3 Jun 46 19 Jun 46 4 Apr 47 MC/D 7 Mar 47

Class Notes:
FY 1912 (Act of 4 Mar 11). In mid-1910 the General Board distributed for comment draft characteristics of future tugs. On 31 Oct 10 it forwarded the characteristics of seagoing tugs that it recommended for vessels to be authorized in Fiscal Year 1912. They were to be capable of keeping the sea in any weather and of carrying deck loads, the Board noting that tugs were frequently used for transportation purposes and for handling target gear. Quarters for officers and crew were to be arranged generally as in the PATAPSCO, although this design was not otherwise referred to. They were to have two or more boilers capable of using coal or oil fuel, robust yet simple engines able to sustain the many reversals to be expected, and a single screw designed with special reference to towing. They were to be fitted as wrecking and fire tugs. The tugs were to have fuel for an endurance of not less than 4,500 miles and the Board recommended that they have at least 15 knots speed.

An accompanying memorandum explained that the tugs POTOMAC and PISCATAQUA (see AT 49-50) had 2,000 HP and 16 knots speed while PATAPSCO and PATUXENT had 1,160 HP and 13 knots speed. 15 knots was considered a good compromise speed to enable the new tugs to accompany the fleet, with a small allowance of speed in excess to the fleet's 14 knots to compensate for the possible loss of speed in a seaway due to their small size. One commentator noted that these characteristics, particularly with regard to speed, would require very large tugs.

Reflecting the General Board's intent that these tugs accompany the fleet, these were the first tugs included in the "Increase of the Navy" section of the annual Congressional appropriation act and a sum of $215,000 was provided for each one. On 10 Mar 11 the Bureau of Construction and Repair forwarded to the General Board a preliminary design calling for a displacement of 1,100 tons, dimensions of 183' oa, 175' pp x 34' molded, 35.4' extreme x 15' maximum draft, and a speed of 14 knots produced by a 1,800 IHP reciprocating engine with a single screw and two coal-fired boilers. Endurance would be 4,500 miles at 12.5 knots and the designed complement was 4 officers and 38 men. The Bureau noted that the large size of the vessel with considerable sheer giving high bows would meet the requirements for seaworthiness, while the beam would give large initial stability with a view to carrying deck loads. The Bureau considered it impracticable and undesirable to provide for both coal and oil fuel and fitted the ship's tanks for water only. With reference to speed, BuC&R and the Bureau of Steam Engineering adopted 14 knots as it did not appear practicable to provide for 15 knows without allotting too large a proportion of weight to the machinery at the expense of coal supply and radius of action. The General Board approved this preliminary design without changes on 15 Mar 11.

On their 24-hour trials these two tugs failed to make their contract speed of 14 knots, SONOMA making 13.08 knots with 1,596 IHP and ONTARIO making 13.23 knots with 1,517 IHP. The contractor paid a penalty of $6,184 for the speed shortfall in ONTARIO. They, along with PATAPSCO and PATUXENT, served as tenders to the Atlantic Fleet before World War I. As such they became associated with the Navy's relatively new Mine Force. A September 1916 report stated that the four fleet tenders would soon be thoroughly equipped for mine sweeping and already had removable tracks for mine planting. The General Board submitted characteristics for minesweepers on 19 Oct 16, and when the Navy began an emergency construction program of LAPWING (No. 1) class minesweepers in May 1917 the dimensions of the new ships were very similar to those of the SONOMA class tugs. In late 1918 all four of the prewar fleet tenders were assigned to the minesweeping group at Queenstown, Ireland. Both SONOMA class tugs remained in continuous commission between the wars. ONTARIO was converted from coal to oil at Pearl Harbor in 1941 and SONOMA was probably also similarly upgraded.

Ship Notes:
AT Name Notes
12 SONOMA To ATO-12 15 May 44. Struck by falling Japanese bomber in San Pedro Bay, Leyte, sank off Dio Is. in 18 feet of water and hulk abandoned.
13 ONTARIO To ATO-13 15 May 44. Station ship at Tutuila, American Samoa, from 1922 (relieved FORTUNE) to January 1941. Sold (awarded) to Marine Salvage, Wilmington, Calif., to buyer 4 Apr 47.

Page Notes:
AT        1911
Compiled:        02 Mar 2013
© Stephen S. Roberts, 2002-2013