Swift Boat
Patrol Craft Fast Specifications
A Mark I Swift Boat circa 1967

NAVSHIPS 250-452 description of a PCF (Patrol Craft Fast)

Copyright � 1998-1999-2000-2001-2002-2003 Lawrence J. Wasikowski. All rights reserved.
Any use of the information presented below, without prior written approval, is strictly prohibited.

Read about the Swift Boat Design History

Length: 50 foot 1.5 inches
Beam: 13 foot 6.5 inches
Full load draft: Hull: 3 foot 10 inches / Skegs: 4 foot 10 inches / Navigation: 5 foot 10 inches
Height: Main deck at pilothouse: 3 foot 8 inches
Top of .50 caliber gun tub: 11 foot 6 inches
Top of the radar mast: 16 foot 9 inches
Construction: Hull and superstructure: All-welded, 1/4 inch aluminum alloy plate
Paint Scheme: Deck gray with varying amounts of black added.
White service locker lid with black boat numeral
Blue circle with white star overlayed on pilothouse overhead
Boat numeral in white on either side of the bow and across the stern
Weight: 36,913 lbs. empty / 47,047 lbs. with full fuel and ammunition loaded

Engines: Two (2) General Motors 12V71"N" Detroit marine diesels, each equipped with two (2) 4-71 turbochargers
and N70 type injectors, Each rated at 480 horsepower. SM-118 Hydraulic Marine Gear Clutch with 1.15:1
reduction gears driving two counter-rotating screws.

Electrical: Two banks of twenty-four (24) volt batteries providing the source of electrical power for main engine
starting, general purpose lighting, search lights, navigational lights, and the radar. Each bank charged
by its own alternator. Primary supply from the starboard bank, with the port bank in standby. In the case
of emergencies, the two banks could be placed in parallel.

An auxillary 6.0 KW Onan, 120 volt, 50 amp, single phase, 60 cycle AC generator providing power to the
AN/URC-58 HF radio, signal lantern, refrigerator, freezer, other galley equipment and the AC outlets.

Electronics: Decca D202 (X-band, 3cm) surface search radar. Maximum range scale: 24 miles. Utilized fixed range
rings and a relative bearing presentation. Range discrimination was 30 yards, on the 1.5 mile scale,
with a bearing accuracy of 1 degree. Maximum detection range of a small wooden junk: 3 miles, with
an estimated 90% detection of small junks at 1 mile. In average sea conditions, a 90% detection rate
for steel hulled trawlers was assumed to be 5 miles.  Power consumption was 200 watts DC.

Raytheon DE176A Fathometer: Dual range. 240 foot maximum depth reading

AN/URC-58 HF radio: 2 to 15 MHZ. Upper/Lower sideband, AM or CW.
Output: 100 watts. Input Power: 120 VAC, but capable of 24 VDC operation.
Of little or no effective use during 1967.

AN/VRC-46 VHF FM radio: 30.00 to 79.95 MHZ. Installed during 1967.
Primary Coastal Surveillence Center guard channel communications.

AN/PRC-10/25 VHF FM, portable field radio: 30.00 to 79.95 MHZ .
Primary communicatons until the AN/VRC-46 radio was installed.

AN/URC-4 Survival/Emergency radio

Other: Danfort/White magnetic compass. Installed in the pilothouse

Rotatable spotlight: used to illuminate targets at 250 to 300 yards range.
Mounted on the pilothouse overhead and controlled by the helmsman

A 6 inch portable signaling lantern: visible at a 4 mile range, when used from the guntub

Hand held observers magnetic compass

Armament: Twin .50-caliber Browning machine guns (heavy barrels), installed in a Mark 17/Mod 1 manually operated,
twin-scarf-ring mount. Capable of firing at 450-550 rounds per minute. Equipped with ammo trays with 500
to 600 rounds per gun. The machine guns were located on the boat centerline, in a guntub, mounted on top
of the pilothouse. The maximum range was in excess of 7,000 yards. The effective accuracy decreased
rapidly in excess of 2,000 yards, but effectiveness at 1000 yards and under was excellent. Typical patrol
ammunition load carried was between 20,000 to 25,000 rounds.

81mm Mark 2/Mod 0, trigger fired naval mortar with a .50-caliber Browning machine gun (heavy barrel)
fixed atop it. The machine gun was equipped with an ammunition tray/can containing 100 to 300 rounds.
The combined weapon mounted to a centerline tripod on the fantail with a two way swivel.

      - Range of the 81mm mortar: 3,940 yards elevated and 1000 yards direct

      - Trigger fired capacity: 10 rounds per minute.

Typical 81mm ammunition load carried on board in the two main cabin floor lockers and the stern mounted ready service locker was:

     - High Explosive with point detonated fuse: 80 rounds

     - White Phosphorus with point detonated fuse: 15 rounds

     - Illumination with timed fuse: 20 rounds

Various crew member weapons included: M-79 grenade launchers, M-16 rifles, a 12 gauge Ithaca riot gun, .45 and .38 caliber pistols, various types of hand grenades (fragmentation, concussion, thermite and red, yellow and green smoke), and a Very Pistol Flare Gun.

Turning radius: 75 yards when cruising at 20 knots

Stopping Distance: 2 1/4 boats lengths (112 feet) in 9 seconds, from maximum speed

Fuel: 828 gallons, diesel or JP-5 in an emergency. Stored in three fuel tanks (2 aft, 1 amidships)

Speed: 32 knot designed maximum

Actual engine RPM versus speed data varied widely from boat to boat depending on the type of fuel used,
loading of the boat, and calibration of the remote engine tachometers. The maximum speed was usually
obtained with the engines turning in the neighborhood of 2200 RPM. Accurate knowledge of speed thru the
water was not a navigational necessity when operating in the rivers and/or close to the shoreline.

The height of the sea significantly curtailed the speed capabilities of the PCF. This effect varied with the
course of the PCF relative to the direction of the seas.

Average estimates in the most severly limiting condition for a PCF, heading directly into the seas while
remaining within the limits of violent pounding, are listed in the table below:

Sea State
Wind Speed
Revs Per
Max Speed
Avg Speed
2 to 3  9 to 12 1850 21.0 21.0
3 to 4 12 to 15 1200 11.2 10.5
5 to 6 15 to 18   600   6.3   4.5
  Range versus Speed:

Revs Per
Avg Speed
Per Hour
800   8.1   8 840 100
1000   9.8 10 780   80
1200 11.2 18 600   44
1400 13.6 20 540   40
1600 17.6 28 400   28
2000 23.5 75 250   11


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