Torpedo Attack Table

The Torpedo Attack Table was a Torpedo Control teaching aid to practice torpedo attacks.

Torpedo Attack Trainer
Early design sketch

It was described in the Annual Report of the Torpedo School, 1915 as a "Torpedo Attack Trainer", similar the Gunnery Spotting Table. It was a "play at home" edition of torpedo attack, requiring a fairly large open area, with the model "firing ship" with a Torpedo Director mounted on it and the model "target fleet" being about 25 feet from each other. It was to be a casual affair "very easily made in the ship."

Initial Design as "Trainer"

The "Torpedo Attack Trainer" was to have comical little "own ship" cut from wood and able to revolve atop a fixed wooden compass disc 16 inches in diameter and marked 0 to 180 degrees. A pointer on the ship would indicate against this scale, and a torpedo director would be mounted on the toy ship. If it is desired to practice for trainable tubes, the director could also be allowed to train over the ship.

The "target fleet" would be small models or cut-outs of ships of approximately 150 feet to the inch, arranged 500 yards apart along a wooden batten 42 inches in length and able to revolve around a fixed, graduated disc marked to show inclination of the batten as seen from "own ship". A painted sky and sea surface concealing the batten would provide a fairly clean view to the man at the torpedo director.

The man being tested would man the torpedo director and four assistants would manage the simulated attack, using

• a Dumaresq (fitted so enemy heading can be set by inclination, a Mark IV being preferred)
• an Elliott Range Keeper Mark III (being pressed into service as a bearing clock -- if none were available, a second Vickers clock could be used despite less convenient markings)
• a Vickers Range Clock
• a stopwatch

The officer in charge would specify enemy's inclination, bearing, range and speed, as well as own speed. The dumaresq operator would set inclination, bearing, and the two speeds on his instrument, and the Vickers clock man would put the range on his clock as well as the range rate provided him by the dumaresq number. The Elliott clock man sets the bearing on his device, 100 yards being treated as 1 degree. The dumaresq man (or, preferably, the Elliott man) converts the indicated Dumaresq Deflection to a bearing rate by use of a table, and the Elliott man applies this as his rate using the same 100 yards equals 1 degree conversion. Lastly, "Own ship" is swung to the enemy bearing, the target fleet's inclination is set as specified, and the run is ready to begin.

The clocks and the stop watch are started. The range is periodically read off the Vickers clock for the firing officer to hear, and available hands spin "own ship" to the new bearing every so often, according to the Elliott's indications. The range rate and bearing rate is modified on the clocks as the bearing changes, and the inclination of the enemy can also be applied from the dumaresq. The firing officer being tested can set his director's enemy heading and can choose to command a turn which alters the bearing on "own ship" and the dumaresq and Elliott to suit.

When the firing officer wants to fire, he calls it out (perhaps soon after training his tube or ordering a course change to bring sights on). The stopwatch and both clocks are stopped and the result of the shot plotted visually.

Final Design as "Table"

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  Firing Ship

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  Target Carriage

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  General Arrangement

The final design is described in the Annual Report of the Torpedo School, 1918

The initial idea had been refined considerably and it was now referred to as the "Torpedo Attack Table", owing to its becoming a table of 8 foot sections that was 32.5 feet in length when all were in place. If space did not permit the whole length to be assembled, one or two sections could be omitted.

The table operators resided at one end of the table, and the director table with "own ship" sat beyond the other end. The target carriage could run along a table-top track so that the "range" (indicated on a tape near the operators) could be changed with respect to the model firing ship with the director atop it. The operators used reels and wires to change inclination of the target, range of the target and bearing of the target (the "own ship" would rotate when this was worked).

A clever screen on the edge of the target carriage nearest the director concealed the batten from the man being tested, and each little model target ship sat on an independent "bobbin" turntable atop the batten where a single knob could dial them out of line-ahead formation so they could appear to be on a line of bearing or allow them to zig-zag.

The means of changing the target batten inclination proved coarse enough with 5 degree quantization that it was clear to the man being tested that inclination had been changed. An electrical solution employing a modified Vickers Mark III FTP receiver to set inclination proved able to do 0.25 degree steps and worked nicely enough that it was hoped to slip that in to the final articles.

A set of gimmicks that would not be out of place in a sideshow permitted various conditions of visibility to be simulated, but required that the training be done indoors:

Setting		Visibility (yards)	How to achieve desired effect
Day	Clear	3,000 to 22,500	clear lamps in low foreground holders and overhead reflector, no dimming, and a light background
	Variable	3,000 to 22,500	Use dimmer switch or turn off foreground and/or overhead lights
	Sunrise/set	varies	Use red lamps, and dim as required.
	Misty	varies	Use clear lamps in overhead reflector and a sheet of lightly smoked glass at the firing ship end of table.
	Smokescreen	varies	Frayed yarn, either white or dipped in black ink to render them brown can be draped over target models
	Fog	500 to 2,750	Frosted glass in near end of target carriage, and a finger lamp dimmed appropriately in the low background holder
Night	Clear	500 to 5,500	Blue lamps in low foreground holders and overhead reflector with light background. Dim as desired and tweak scale of models.
	Cloudy/Dark	500 to 2,750	As above, use dark background and 1/300th scale models
	Enemy Searchlight	varies	Lights with lenses in the front board of the carriage produce this effect, concealing the ships behind them.
	Own Searchlight	varies	A magazine lamp with a suitable projector on the lens is placed near own ship.
	Own Starshells	varies	A pair of lamps on the rod supporting the overhead reflector can be lit for the duration of the star shell.

Allocation

By mid 1919, twenty units of the approved design were being manufactured for allocation as follows: three to H.M.S. Vernon (Torpedo Training School)|Vernon]], two each to Port Edgar and Lyness depot bases, and one each to Immingham depot base, Dover depot base, Defiance, and depot ships Actaeon, Apollo, Woolwich, Blake, Diligence, Greenock, Sandhurst, Hecla, Dido and Blenheim.

Each table was to be accompanied by a T.D.S. Mark III and a Pattern 36 signalmen's instructional box.

Bibliography

• Template:BibUKARTS1915
• Template:BibUKHandbookOfTorpedoControl1916
• Template:BibUKARTS1917
• Template:BibUKARTS1918