To review the mechanics of the 3-M system, refer
to “The Ships’ 3-M Systems” chapter of the Military
Requirements for Petty Officer Third Class, NAVED-
TRA 12044. Although that chapter provides an excel-
lent description of the 3-M systems, the official ref-
erence for the 3-M systems is the Ships’ Maintenance
and Material Management (3-M) Manual, OPNAV -
INST 4790.4. You may also wish to read Introduction
to 3-M Systems, NAVEDTRA 13092, which gives
a short but very informative explanation of 3-M sys-
tems and procedures.
AVAILABILITY TYPES
An availability is an assignment of a ship to a
repair facility for repairs beyond the capability of the
ship’s force. Besides regular overhaul, several types
of availabilities are assigned, according to the needs
of the individual ship or the fleet. These are restricted,
technical, and intermediate-level maintenance activity
availabilities.
Restricted Availability
A restricted availability (RAV) is normally as-
signed for emergency repairs of prime systems that
prevent the ship from fulfilling its mission. When
emergency repairs to primary systems cannot be made
by the ship’s force, the commanding officer may
request the TYCOM to assign a restricted availability
for the repair of a specific system. During an RAV,
the ship is incapable of performing its mission.
Technical Availability
A technical availability (TAV) is assigned when
repairs on noncritical systems or equipment must be
made by a repair facility or yard. These repairs do
not affect the ability of the ship to complete its mis-
sion. If necessary, the ship can get under way without
the system or equipment being repaired.
Intermediate-Level Maintenance
Activity Availability
An intermediate-level maintenance activity avail-
ability (IMAV) involves repairs made by either afloat
repair activities (tenders and repair ships) or shore
intermediate maintenance activities (SIMAs). Its pur-
pose is to accomplish as much intermediate-level
maintenance and repair work as possible within the
workload limitations, the available funds, and the rela-
tive priority of the required work.
Although the primary emphasis of a SIMA effort
is on repair work, authorized ship alterations and alter-
ations equivalent to repair are undertaken as SIMA
workloads permit.
UPKEEP PERIOD
The upkeep period is time in a port where the
facilities of a yard or a tender are available for routine
maintenance that cannot be completed while the ship
is under way. Upkeep scheduled with the assistance
of a tender or a repair ship is sometimes referred to
as tender availability.
SHIPYARD OVERHAUL
Ships are assigned availabilities at shore-based
repair activities as directed by the CNO. The first
scheduled overhaul is normally granted to a ship after
an initial operating period of approximately 2 years.
Thereafter, scheduled overhauls depend on the ship
type.
The amount of time in the shipyard for these over-
hauls varies. For example, if the shipyard works on
a one-shift basis, the overhaul often requires 6 months
or longer. The employment schedule, an operating
directive furnished by the TYCOM, indicates when
a ship is scheduled for overhaul.
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