The Engineers Bell Book, NAVSHIPS 3120/l, is a record of all bells, signals, and other orders received by the throttleman for movement of the ships propellers. Entries are made in the Bell Book by the throttleman (or an assistant) as soon as an order is received. Entries are usually made by the assistant when the ship is entering or leaving port, or engaging in any maneuver that is likely to involve numerous or rapid speed changes. This procedure allows the throttleman to devote his or her undivided attention to answering the signals.

The Bell Book is maintained in the following manner:

1.A separate bell sheet is used for each shaft each day, except where more than one shaft is controlled by the same throttle station. In that case, the same bell sheet is used to record the orders for all shafts controlled by the station. All sheets for the same date are filed together as a single record.

2. The time of receipt of the order is recorded in column number 1.

3. The order received is recorded in column number 2. Minor speed changes (generally received via revolution indicator) are recorded by entering the number of rpm ordered. Major speed changes (normally received via engine order telegraph) are recorded using the following symbols:

a.1/3-ahead 1/3 speed

b.2/3-ahead 2/3 speed

c.I-ahead standard speed

d.II-ahead full speed

e.III-ahead flank speed f.z-stop

g. B1/3-back 1/3 speed

h. B2/3-back 2/3 speed

i. BF-back full speed

j. BEM-back emergency speed

4.The number of revolutions corresponding to the major speed change ordered is entered in column 3. When the order received is recorded as rpm in column 2 (minor speed changes), no entry is made in column 3.

5. The shaft revolution counter reading (total revolutions) at the time of the speed changes is recorded in column 4. The shaft revolution counter reading-as taken hourly on the hour while underway-also is entered in column 4.

For ships and craft equipped with controllable reversible pitch propellers, the propeller pitch in feet and fractions of feet set in response to a signaled speed change, rather than the shaft revolution counter readings, is recorded in column 4. The entries for astern pitch are preceded by the letter B. Each hour, on the hour, entries are made of counter readings. This helps in calculating engine miles steamed during the time the propeller pitch remained constant at the last value set in response to a signaled order.

On ships with gas turbine propulsion plants, a bell logger provides an automatic printout each hour. This printout is also provided whenever propeller rpm or pitch is changed by more than 5 percent, when the engine order telegraph is changed, or when the controlling station is shifted. Provision must be made for manual logging of data in the event the bell logger is out of commission (OOC).

Before going off watch, the EOOW signs the Bell Book on the line following the last entry for his or her watch. The next officer of the watch continues the record immediately thereafter. In machinery spaces where an EOOW is not stationed, the bell sheet is signed by the watch supervisor.

NOTE: A common practice is also to have the throttleman sign the Bell Book before it is signed by the EOOW or his or her relief.

The Bell Book is maintained by bridge personnel in ships and craft equipped with controllable reversible pitch propellers and those in which the engines are directly controlled from the bridge. When control is shifted to the engine room, however, the Bell Book is maintained by the engine-room personnel. The last entry made in the Bell Book on the bridge shows the time that control is shifted. The first entry made in the Bell Book in the engine room shows the time that control is taken by the engine room. Similarly, the last entry made by engine-room personnel shows when control is shifted to the bridge. When the Bell Book is maintained by the bridge personnel, it is signed by the officer of the deck (OOD).

Alterations or erasures are not permitted in the Bell Book. An incorrect entry is corrected by drawing a single line through the entry and recording the correct entry on the following line. Deleted entries are initialed by the EOOW, the OOD, or the watch supervisor, as appropriate.