Convoy Zig Zags ww2

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
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

stan mayes
8th May 2009, 18:38
Hello Sid,
In every convoy I have experienced Zig Zag courses -not too bad during daylight and fair weather but during the hours of darkness and in foul weather it was a nightmare.I don't think it occurred very often at nighttime as there would be problems in contacting the ships except by Aldis lamp.
But I do remember doing it a few times [with near misses of collisions] ..
Possibly the Commodore would display flag signals just before dusk if we were to zigzag during the night -maybe you can clarify that.
Also I remember there were times when we had a blue stern light when it was very dark and moonless.
It is a long time ago to try to recall these movements.

John Rogers
8th May 2009, 18:50
The trick of towing a raft or something similar behind still fascinates me when I hear how they would do it bad weather or fog. Sid or Stan,did you ever use this trick.???


8th May 2009, 19:52
The last few convoy exercise I been on with the US Navy the Blue Stern light is still used. The flags have been replaced with what the RO called super secret squirrelly stuff (encrypted radios).

On the practice convoys the convoy leader would be changed and the new leader would order a new course changes from a book. While I was on the bridge for coffee with the Captain the new leader made up a turn to visualize the course changes I placed my coffee down and using my hands I realized that the new command would cause a t bone on the second turn. Just then the Navy observer came back with Whiskey, Tango, Foxtrot, Oscar. A new convoy leader was selected and a new course changes were given.

stan mayes
8th May 2009, 19:57
Hello John,
Yes,mostly called a fog buoy and most were simply a tube with wings to keep it above the surface and a spout was on the tube. Towed behind the ship and as the water passed through the tube it sent spray into the air.
I recall some ships having old hatchboards as fog buoys- they would often spring 6 or 8 feet into the air..
In dense fog a lookout man would be in the bows and sometimes an officer also.Of course there was a continous sound of ships sirens.
I was in the tanker Neritina on her maiden voyage from the Clyde December 1943.
During atrocious weather and poor visibility in convoy ON 215 we had a problem with the steering gear and being light ship we were blown accross the sea and were in collision with the tanker F.J.Wolfe .
We had an AB lookout for'ard reporting the fog buoy of the ship ahead and I guess when he saw the imminent danger he went sprinting along the flying bridge to safety.
We arrived New York on 28th December and were in a drydock in Brooklyn for nearly a month under repair.

8th May 2009, 20:39
Small world ! I was on the F J WOLFE as 3rd Mate for a year.
I can't recall zigzags at night. We had torches on the bridge with a blue shade and would signal to the ship abreast at night. Fog buoys were a good thing as you could keep the spray in sight. In one convoy - NY to L'pool we had the sister ship pf the WOLFE in our column - the D L HARPER. She was a twin screw motor ship and had great difficulty because of her critical speed being the same as the convoy's. She was all over the place.
Fog was a real problem, wasn't it ? I was on Fort Camosun - Middlesborough to Baltimore in ballast and we had a lot of fog. We had an Indian crew and there were half a dozen sheep on board which they slaughtered in their cruel way. I can remeember the incongruity of being on watch in thick fog with the whistle being blown and the poor sheep ba-aing away as they wandered around the foredeck with the ship rolling gently.

stan mayes
8th May 2009, 20:56
I remember you telling me you had sailed in F.J.Wolfe and I was looking for confirmation when you replied here.
At the time of the collision I believe she had a US flag but later was taken over by Anglo American Oil Co?
She gained a bad record in convoys.