Zig Zagging Ships: What Is It And Does It Help?

Well done, Ryan. When I saw the thumbnail, I held my breath, waiting for the inevitable re-litigating of the sinking of the Indianapolis. We got through a whole video on the topic, without picking at that scab.

I learned lots about WWII sub vs surface ships from the original Star Trek "Balance of Terror." That was a reworked Enemy Below, which I discovered later.

I can only confirm that from the many U-boat sims I've played, and even Pacific War sims with US boats, zig-zagging complicated torpedo targeting quite a bit at longer ranges

zigzagging really isnt about avoiding an individual torpedo, its about not being where the submarine thinks you are going to be.

Zig Zag plans still exist. A publication is in every CIC with all of the plans. We used to play with the cruise ships in the carribean sea. They didnt have the plans so the OOD would contact them via bridge to bridge radio and give them the plan. Plans exist for a base course and speed made good . We would be known as United States warship . And they wouldnt know who we were unless they stuck around until daylight. There are many other threats to shipping than submarines. Pirates off the east coast of Africa use glorified motorboats for a great example. Time and a place is what I am saying. Every practice still has relevancy. You just have to know practice and adapt to current situations. Fancy electronic gizmos are great until the break.

I always thought it was because of the rum ration. Good to know.

In WW2 fast ships were often better off not zigzagging and transiting an area infested with enemy submarines at 30+ knots, because unless you were very unlucky, the sub couldn't get a good fire control solution. But that eats up a lot of fuel; much more than zigging st 20 kts. Today, there is little reason to ZZ because modern anti-ship torpedoes are faster, longer ranged, and self guided.

This reminds me of another naval system, the "Daszzel" paint scheme. In WW-1, the Royal Navy, partly to deal with the new U-boat threat, but also surface ships, came up with a wild, abstract art-like paint scheme. They would paint angled stripes in all directions, squares, rectangles, rhomboids, etc. in different sizes and lengths and even colors (although hard to tell in B & W photos). Unlike traditional land-based camouflage, the RN realized they could not make ships disappear at sea. The theory was the conflicting shapes would at certain angles or lighting confuse observers as if they were going right or left, or turning towards or away from the observer, and also make it difficult to determine the ships range. When WW-2 broke out on September 1st, 1939, the patterns came back. But as the war progressed, and as radar became more common, the navy stopped painting. Although the effectiveness of daszzel on watch lookers was questionable, it diffidintly did not fool radar.

One example of zig zag backfiring was with hms Suffolk and Norfolk, during the Bismarck chase , as while doing zig zagging , Bismarck would be off and on the radar display. It was when Bismarck was off the screen , she turned and they lost all contact

Capt McVey of the USS Indianapolis was court martialled for "hazarding his ship by failing to zigzag"

Zigzagging was apparently a thing through at least the 1970s. I have two Chelsea zigzag clocks. One clock is in a phenolic case from 1941 and one is in a factory flat black painted brass case with a 1973 serial number. The Chelsea clocks have two internal wheels with overlapping patterns which close together two electrical contacts which protrude through the case. The contacts stay closed for a fairly long time so I believe they controlled the steering gear rather than just ringing a bell. The Chelsea zigzag pattern is fixed. The Zigzag clock has a hack lever near the one o’clock position on the outer rim of the dial. The hack lever stops the clock. The time could be set with the clocks stopped and then all zigzag clocks in the convoy could be started together coordinated by either a visual or radio signal. Seth Thomas also made zigzag clocks which used metal pins to be inserted into a plate to change the zigzag pattern. The Seth Thomas clocks operated a mechanical lever which was coupled to equipment controlling the steering gear. Zigzagging by clock goes back to approximately WW-I. I have seen some apparently hand built zigzag control panels with modified pilot house clocks having wires operating light bulbs, turning bulbs on and off in the desired pattern.

LCDR, USNR(Ret) here. I was on ships in the 1990’s and we still had NATO zigzag plans on the bridge. They had “Very Long Leg Plans” (VLL), “Long Leg Plans” (LL), “Medium Leg Plans” (ML), and “Short Leg Plans” (SL) depending on how much distance you covered between course changes. They were lists of how far, and in what direction you steered away from the base course. All plans wrapped around, in the sense that when you finished the full plan, you were back on track (not to the right or left of your intended track) and could resume the plan from the beginning. You could also combine plans, running say, an SL plan and a VLL plan at the same time. You just add the course offsets. To start a zigzag plan, the commander would tell you the time you start zigzagging (i.e. when you first change course), and at what point in the plan you are supposed to be at that time (i.e. When the zigzagging starts, you go to the half-way point of the plan and start from there.) As to how effective they’d be now, well…I was on USS MERRILL (DD-976) as missile officer, which meant Harpoon and Tomahawk anti-ship missiles. The hardest part of this was trying to predict the target’s movements far enough in advance that the missile would not be searching an empty stretch of ocean. Even the Chinese ballistic missiles need to be able to predict the ship’s position a bit in advance or it won’t be able to change course enough in terminal guidance. So yes, I think zigzagging will still have a part in Naval Warfare for a long time to come.

You don't see this so much today because of guided torpedoes (be they active homing or wire-guided). The OG goal was to not be in the place where the firing solution said you'd be because unguided torpedoes were aimed at points in the sea. Now they can get change directions to compensate for target movement.

Zigzagging wasn’t only used to dodge submarines & torpedoes. The battleship Bismarck used zigzagging to shake off the British ships that were monitoring her. The destroyer USS Johnston zigzagged to dodge enemy shells during her charge in the Battle off Samar

Works so long as there's a good amount of time between the enemy firing and the round/missile/torpedo/whatever hitting you. Works the same way when they'd avoid AA guns during WWII. AA guns (and other munitions) need to predict where you'll be then shoot there. If you change your speed/direction enough, it'll basically be impossible for them to predict anything and then it just becomes a volume of fire and luck game.

Ideas for future videos: Battleships escorting convoys, what is a convoy and how did it work? The story of the SS Stephen Hopkins United States Navy Armed Guard

Zig-zag, I would say, was very effective. As the German submarine losses increased in 1942-1943, they had to shoot from further distances while submerged, which severely limited their effectiveness and maneuverability. The ideal situation for a German submarine attack would be from less than 1000 meters to the target on the surface at night with a 90 degree angle on the bow (perpendicular) to the target. Mistakes in the fire control solution and zig-zag patterns caused the innovation of the German Type 2 and 3 FAT and LuT pattern-running torpedoes and the Type 4 and 5 acoustic torpedoes. The FAT torpedoes ran in a ladder-type pattern, which means they would travel a specified distance, turn around, travel a shorter distance, and keep this pattern until it hit a target or ran out of fuel. However, zig-zag did have moments where the technique led to disaster, as when the Japanese aircraft carrier Shinano accidentally zig-zagged right into the perfect firing solution for USS Archerfish after trying to evade it.

As a kid in the 1940's we had a family friend who was a merchant mariner who had 3 ships blown out from under him and somehow survived the war. Zig Zigging did not seem particularly effective for him. Perhaps they should have Zagged instead of Zigging somewhere along there.

The Argentine General Belgrano was zigzagging when she was hit by torpedoes in 1982.

"Looks like we've got us a convoy."