SUBMARINES:  CHATHAM BUILT

HM Submarine Snapper

TRIALS AT SEA

Snapper

Monday 29th April 1935
0700 Prepare to leave wall.
0730 Leave for Basin Trim.
0745 Submerge
0850 Surface and proceed to Lock.
0900 Sail for Sheerness.
Swing for Compass at zero tide. Arranged by C.O.
Information re proximity of nearest steel, nearest caole, nearest electric motor etc. being supplied by C.M. Check ship is taking all navigational equipment.

Tuesday 30th April 1935
0900 leave for preliminary trials.
Work up to full speed (11/2 hours) and remain at full speed one hour
On conclusion test steering gear 0-15 P, and S. 0-25 P. and S and take time and pressure for H.O to H.O.
Reduce to 270 revs/min on propellers and test After Hydroplane Gear – 0-10 P and S, 0-20 P and S, 0-30 P and S and H.R to H.D.
Test oily bilge pump at 370 revs/min.
Anchor and cable Trials on completion.

Wednesday 1st May 1935
Spare day
Test steering by telemotor motor system
telemotor system by Capstan unit (e.g. raise periscope)
Telemotor system by hand pump. (e.g. raise periscope)

Thursday 2nd May 1935
Spare day
Leave for 30 our trial as soon after 0800 as possible
Four periods of six hours each at speeds, responding to 1/5, 2/5, 3/5 and 4/5 full powers, i.e. 220 revs/min, 280, 340 and 390 revs/min together with six hours on measured miles at about revs (usually takes 2 1/2 hours for four runs each way

Preferable to do it measured mile runs as soon as the visibility permits . Also to get the two highest speeds performed at commencement – should visibility lessen, its may still be suitable for lower speed runs

On measured mile take runs varying from ½ mile to 2 miles before coming on to mile to ensure that conditions have settled

Take times of commencement of run, time or miles, wind and sea conditions and course.

Try Kite Aerial as convenient
Also Upper Deck C.Cs

Monday of following week
0800 (0900?) Leave for full power trials
1 1/2 hours to work up to full speed. 8 Hours at full speed – last hour or 7th hour on measured mile.
Six recordings on mile
On conclusion try steering gear and also hydroplane gear at 270 revs/min
On the conclusion of and before reducing, go from full speed ahead on engines to slow speed astern (on motors) this should be approximately 60 seconds. (engines will not reverse)

Tuesday
0700. Leave for diving trial.
Previously grease and try out all diving gear very thoroughly, especially periscopes and hydroplane gear.
During diving trial test forward hydroplanes. Also test both hydroplanes in hand . After surfacing ensure blowing main tanks have no effect on circulating water inlet.

Test Main Motors at full speed
Steer by Telemotor system (10 minutes)
Change from power to hand – after hydroplane gear with motor stopped.