sidsal
8th May 2009, 17:59
I have been trying to get a copy of MERSIGS - a manual which ships carried and contained all the flag signals, zigzag details etc which enabled a convoy to be sailed across the oceans without any radio communication at all. I believe it must be still a classified document as I have had no luck.
When danger was anticipated a zigzag would be ordered by the Commodore. A flag signal would be hoisted which would mean, for example ZigZag No 12 to be implimented. All ships would hoist this signal until all ships had it flying.
All eyes on teh commodre ship's bridge wouldpeer through binoculars to check that all ships had the signal falgs up.
Each ship would then look up the details in MERSIGS and it would say,for instance - 1st leg - 30 degrees to starboard - time 10 minutes, 2nd leg 15 degrees to port - time 20 minutes, 3rd leg 20 degrees to port - time 30 minutes. ( I may be adrift a bit as memory fades)
Each ship would then work out the courses from their present course and chalk these up on a board which was placed in front of the helmsman.
On the bridge was a zig-zag clock. It had a rim around its face and moveable contacts. In the above case contacts would be put at 10, 10plus 15(25) and 10 plus35 (45) minutes etc. The clock would be wound up and started when the Commodore ship lowered the flag indicating the start of the zigzag. The ships would all lower their flags and alter course to the first leg. The clock would then be started and when it reached 10 minutes it would sound a buzzer and the 2nd course would be instigated. If I remember rightly the zigzag repeated itself each hour until another flag signal would be raised by the Commodore ship indicating a resumption of course and this would be done on the lowering of the flag.
As you could imagine, time had to be allowed for the ships to work out the relevant courses and as most would have magnetic compasses it called for some quick maths.
On Broklebanks MAIHAR in 1943 in a Meddy convoy, we were joined by HMS Birmingham which had been torpedoed in the bow and which was placed in the middle of the convoy, down by the head and with only 2 of its 4 props threshing away half out of the water. After passing Malta a periscope was sighted and the Commodore ( our ship) hoisted a zigzag flag and the mates quickly worked out courses. We were steering about S85E magnetic and the 1st leg was worked out to be N72E. Unfortunately the 3rd mate's writing of a 7 wasn't clear and to the helmsman it looked like N12E instead of N72E.
On lowering the flag and blowing a long blast to indicate the start, all the ships except for us took up N72 E whilst we veered off to port to take up
N12E.
Panic stations of course on the bridge with Rear Admiral Brodie doing his nut.
We ended up outside the convoy and it took us a good while to regain our
position.
When danger was anticipated a zigzag would be ordered by the Commodore. A flag signal would be hoisted which would mean, for example ZigZag No 12 to be implimented. All ships would hoist this signal until all ships had it flying.
All eyes on teh commodre ship's bridge wouldpeer through binoculars to check that all ships had the signal falgs up.
Each ship would then look up the details in MERSIGS and it would say,for instance - 1st leg - 30 degrees to starboard - time 10 minutes, 2nd leg 15 degrees to port - time 20 minutes, 3rd leg 20 degrees to port - time 30 minutes. ( I may be adrift a bit as memory fades)
Each ship would then work out the courses from their present course and chalk these up on a board which was placed in front of the helmsman.
On the bridge was a zig-zag clock. It had a rim around its face and moveable contacts. In the above case contacts would be put at 10, 10plus 15(25) and 10 plus35 (45) minutes etc. The clock would be wound up and started when the Commodore ship lowered the flag indicating the start of the zigzag. The ships would all lower their flags and alter course to the first leg. The clock would then be started and when it reached 10 minutes it would sound a buzzer and the 2nd course would be instigated. If I remember rightly the zigzag repeated itself each hour until another flag signal would be raised by the Commodore ship indicating a resumption of course and this would be done on the lowering of the flag.
As you could imagine, time had to be allowed for the ships to work out the relevant courses and as most would have magnetic compasses it called for some quick maths.
On Broklebanks MAIHAR in 1943 in a Meddy convoy, we were joined by HMS Birmingham which had been torpedoed in the bow and which was placed in the middle of the convoy, down by the head and with only 2 of its 4 props threshing away half out of the water. After passing Malta a periscope was sighted and the Commodore ( our ship) hoisted a zigzag flag and the mates quickly worked out courses. We were steering about S85E magnetic and the 1st leg was worked out to be N72E. Unfortunately the 3rd mate's writing of a 7 wasn't clear and to the helmsman it looked like N12E instead of N72E.
On lowering the flag and blowing a long blast to indicate the start, all the ships except for us took up N72 E whilst we veered off to port to take up
N12E.
Panic stations of course on the bridge with Rear Admiral Brodie doing his nut.
We ended up outside the convoy and it took us a good while to regain our
position.