The primary objective of Task Force 115 was to prevent the enemy from strengthening his forces in South Vietnam through seaborne infiltration of supplies and munitions. The Viet Cong operated junks, sampans, and other craft within South Vietnamese coastal waters, and limiting this movement became a responsibility of Task Force 115. Over the years Task Force 115 experienced a great increase in resources and the full development of patrol tactics and operating procedures.
The coastal
surveillance operation was organized around nine patrol
sectors covering the 1,200-mile South Vietnamese coast from
the 17th parallel to the Cambodian border and extending 40
miles out to sea. Within these areas, planes, ships and
craft of the U.S. Navy searched for contraband.
The 9 patrol sectors were generally divided into three
zones:
(1) An air surveillance sector farthest out to sea; Various
American aircraft operating from ships offshore and from
bases in South Vietnam, Thailand, and the Philippines flew
search patterns over the Task Force 115 area.
For a brief time in
1965 A-1 Skyraiders operating from carriers covered the
central Vietnam coast. This mission was shared and then
taken over by a patrol squadron based at Sangley Point and
flying the advanced P-3 Orion aircraft.
Throughout this period, five to seven P-2 Neptunes
stationed at Tan Son Nhut near Saigon ranged up and down
the South Vietnamese coast along designated patrol
tracks.
With the withdrawal of the older seaplanes, the Navy
stationed a squadron of 12 P-2's ashore at Cam Ranh Bay and
a detachment of P-3's at Utapao in Thailand.
(2) An outer surface barrier patrolled by large U.S. ships.
The continuing demand
for Task Force 115 vessels resulted in the deployment of 15
Coast Guard high endurance cutters(WHEC) to South Vietnam.
(3) An inner, or shallow-water, barrier patrolled by U.S.
and South Vietnamese boats and craft.
A U.S. Coast Guard WPB 82-foot cutter, one of
26 deployed to Vietnam, cuts through the sea in search of
Communist vessels.
To augment the inshore patrol, the Navy bought 84 Swift
(PCF)boats designed by the Louisiana-based Stewart Seacraft
Company and deployed them to South Vietnam.
Newly built Asheville-class patrol gunboat
(PG), designed specifically for coastal operations in the
Third World, were also added to Task Force 115. The
165-foot PGs capable of 37-knot speeds, carried one
3-inch/.50-caliber gun forward, one 40-millimeter gun aft,
and four .50-calibermachine guns.
Mobile units of Inshore Undersea Warfare Surveillance Group
1, Western Pacific Detachment, deployed to South Vietnam to
form an additional screen. Inshore Undersea Warfare Units
operated a total of 16 large personnel landing craft, 25
Boston Whalers, and 8 picket boats in Operation Stable
Door. The 45-foot picketboats, carried a crew of one
officer and five men and two .50-caliber machine guns,
twin-mounted.
Harbor defense and
surveillance units in the ports of Vung Tau, Cam Ranh Bay,
Qui Nhon, Nha Trang, and Vung Ro constructed harbor
entrance control posts and equipped them with radios and
surface search radars.
To improve the
effectiveness of the anti-infiltration system, the Navy
emplaced surface search radars on Son and Obi islands south
of the Mekong Delta and on Re island east of Chu Lai and
upgraded communications between headquarters, coastal
surveillance centers surface ships and craft, and
aircraft.
Task Force 115 aided the allied cause in other ways. The
naval gunfire support offered by these American and
Vietnamese ships and craft often was of vital importance to
ground units locked in combat. The naval units also served
as blocking forces in encirclement operations conducted
near the coast and on large rivers.
The transportation of friendly troops and the evacuation of
civilians constituted other important tasks. And, as with
most American forces in South Vietnam, the Market Time
units worked to win friends for the allied cause by
building schools, donating food and clothing, and
performing other civic actions.
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In addition, Martin P-5 Marlin seaplanes operated from
seaplane tenders Currituck(AV 7) and Salisbury
Sound (AV 13), periodically anchored at Condore and
Chamislands and at Cam Ranh Bay.
On an intermittent basis, U.S. Army Bird Dog observation
aircraft and South Vietnamese Douglas C-47s watched over
several critical coastal sectors.
Radar picket excort ship
(DER) patrolling part of South Vietnam's
1,200-mile coast.
The WHECs added their search radars, one 5-inch/38-caliber
gun, six .50-caliber machine guns, and two 81-millimeter
mortars to the patrol's firepower. 
These 50-foot, 23-knot vessels, armed with .50-caliber
machine guns and an 81-millimeter mortar, operated from
bases at An Thoi, Danang, Cat Lo, Cam Ranh Bay, Chu Lai,
and Qui Nhon, respectively and became the mainstays of the
Navy's coastal Surveillance force.PCFs on
patrol.
