Renouf Torpedo Tactical Instrument Type F
The Type F ("F" standing for "Flagship") was the most elaborate version of the the family of Renouf Torpedo Tactical Instruments, intended for use in flagships to help them judge torpedo attack and defence at the divisional level and beyond.
This was for use in flagships, and was the most complex model, as it was oriented toward torpedo attack and defence not at the ship level, but the level of a division, a squadron, or even three squadrons. It could also help identify, from the perspective of the fleet being considered, safe and unsafe arcs for one's own torpedo fire.
The device had 3 sets of fitting supplied:
- "Course to Steer" fittings to perform all functions of the Type B
- "Squadron" fittings (which included the avoiding bar) for attack and defence of a division, squadron, or 3 squadrons
- "Own Torpedo" fittings to deal with hazards posed by friendly torpedoes
The Type F's torpedo circles were worked independently from one another, not together as in Types A and B. Its base line ran down the centre of the base plate, essentially doubling the size of the instrument and allowing threats from the starboard to be depicted naturally.
"Course to Steer" Fittings
The device could work a new problem (in attack and defence forms) over the Type B when the fleets were on converging courses, namely "how long before attacker is in position to fire?"
The process was as follows:
- Advance torpedo circles to speed of target fleet
- Set attacker range on the position bar
- Set attacker direction by his bearing (on defensive problems) or by the target's inclination (on attack problems) on position bar
- Place desired track bar to course of attacker
- Set resultant track bar pivot to speed of target fleet
- Place "Course to steer" bar parallel to desired track bar
- Turn resultant track bar so its reading edge cuts speed of attacker on the "course to steer" bar
- Read off time to run 1,000 yards on resultant track bar
- Turn desired track bar parallel to resultant track bar and read off range to run on resultant track bar to reach the pertinent torpedo circle
- Multiply time to run 1,000 yards by this range to run to determine how long before attacker is in torpedo range
The Fleet Bar is depicted in magenta in the figure and can slide and rotate through a pivot fitted on the central base line of the instrument. "It is graduated in thousands of yards each way, which divisions represent the space occupied by two ships in line."
The Position Bar is depicted in orange in the figure, and is graduated in thousands of yards. Rather than pivot on the central base line, its pivot is on the sliding fleet bar. The position pointer is the pivot point on which rides the squadron bar. A second, simpler slider located nearer the hub is called the destroyer position pointer.
The Squadron Bar is depicted in magenta in the figure and is pivoted on the destroyer position pointer which in turn rides on the position bar. "It carries three small bars on the underside, each of which represents a squadron of eight ships. Each squadron is pivoted at the leading ship..." This arrangement permitted the squadron bar and its underslung 3 squadrons (depicted as white lines in the illustration) to be arranged in any manner relative to the primary pivot on the base line.
To work an attack problem, the enemy is on the base line:
- Advance the torpedo circles by the enemy's speed
- Rotate the Fleet Bar to the disposition of the guides of the enemy squadrons, with the centre squadron being at zero on the fleet bar. It was acknowledged that this would be difficult to do, and an optimistic suggestion is made to rely on reports from plots, kite balloons or aircraft.
- Rotate Position Bar to enemy inclination
- Set the Squadron Bar to the proper range and arrange the little squadrons underneath to match own disposition
As I failed to photograph page 188 of ARTS1918, I will aim to complete this this later. [TO BE CONTINUED - TONE]
"Own Torpedo" Fittings
Owing to blurry photos and a missing photo for page 188, I will seek to document this later. [TO BE CONTINUED - TONE]
Tips for Torpedo Look-outs
It was noted in the Annual Report of the Torpedo School, 1918 that if one's own ship at position O were threatened by an enemy fleet on line AB (in Figure 15), that portion of the line CB was the portion that could actually fire. Because a torpedo that is aimed properly to endanger our ship will maintain a constant bearing throughout the course of its flight, torpedo look-outs could be told that the arc COB is the one to pay special attention to, as torpedoes that are going to hit would have to remain within this arc.
History and Deployment
These were not allocated until after the war's end. In 1919, nine were to be manufactured by Elliott Brothers and allocated in this order: Queen Elizabeth, Revenge, Barham, Lion, Vernon, Defiance, Iron Duke, King George V and Hood. No further instruments of this type were immediately planned. In 1920, the plans for distribution had been altered slightly: Queen Elizabeth, Revenge, Barham, Hood, Vernon, Defiance, Iron Duke, Orion and the Staff College at Greenwich.
In 1920, the re-organisation of the fleet caused a revision in the allocation strategy for Renouf instruments. A total of nine Type Fs were to be issued, with six of these going to warships (Queen Elizabeth, Barham, Hood, Iron Duke, and, oddly, Orion) and the others to Vernon and Defiance and the Staff College, Greenwich.
In 1921, all types of Renouf instruments were under evaluation for ideas that would render them "less complicated and less liable to foul."
- Annual Report of the Torpedo School, 1918. p. 181.
- Annual Report of the Torpedo School, 1918. Plate 127.
- Annual Report of the Torpedo School, 1918. p. 181.
- Annual Report of the Torpedo School, 1918. p. 187.
- Annual Report of the Torpedo School, 1918. Plate 128.
- I am not sure I understand this at all. The illustration shows that the bar is marked 0 to 22, with 16 being equivalent to 10,000 yards on the baseplate.
- Annual Report of the Torpedo School, 1920. Plate 36.
- Annual Report of the Torpedo School, 1918. Plate 129.
- Annual Report of the Torpedo School, 1918. Plate 130.
- Annual Report of the Torpedo School, 1918. p. 189, Fig XV.
- Annual Report of the Torpedo School, 1918. p. 189.
- Annual Report of the Torpedo School, 1919. pp. 119, 120.
- Annual Report of the Torpedo School, 1920. p. 91.
- Annual Report of the Torpedo School, 1920. pp. 90, 91.
- Annual Report of the Torpedo School, 1912. p. 144.
- H.M.S. Vernon. Annual Report of the Torpedo School, 1917. Originally C.B. 1474. Copy 7 at The National Archives. ADM 189/37.
- H.M.S. Vernon. Annual Report of the Torpedo School, 1918. C.B. 1527. Copy 20 at The National Archives. ADM 189/38.