# WWI German mine layers **URL:** \ **Category:** Factual Questions\ **Created:** [July 2, 2013, 4:07pm UTC](https://boards.straightdope.com/t/wwi-german-mine-layers/662453 "2013-07-02T16:07:08Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![dam0](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@dam0](https://boards.straightdope.com/u/dam0)\ **Post date:** [July 2, 2013, 4:07pm UTC](https://boards.straightdope.com/t/wwi-german-mine-layers/662453/1 "2013-07-02T16:07:08Z")
I’m currently diving at Scappa Flow (where the WWI German fleet was parked and subsequently scuttled) and today we dived the fast mine layer SMS Brummer. According to the excellent pre-dive briefing the mines were stored on the ship in baskets. When it came to laying the mines, the basket and mine went over the side and the basket became the anchor as the two were tethered together allowing the mines to be suspended mid water. My question is (and the skipper didn’t know) did they have the mines sorted with set cable lengths ready at manufacture or did they cable then on the ship before throwing them over the side. ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [July 2, 2013, 5:13pm UTC](https://boards.straightdope.com/t/wwi-german-mine-layers/662453/2 "2013-07-02T17:13:07Z")
Don’t know - but isn’t there a risk of unexploded ordnance in Scapa Flow which would pose a risk to divers? Sounds like a creepy and cold place to dive. ---
**Author:** ![dam0](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@dam0](https://boards.straightdope.com/u/dam0)\ **Post date:** [July 2, 2013, 5:59pm UTC](https://boards.straightdope.com/t/wwi-german-mine-layers/662453/3 "2013-07-02T17:59:57Z")
Not really. When the armistice was agreed the ships were offloaded of anything explosive in Germany before they were surrendered to the British fleet. It’s one of the best dive sites in the world, 10 degree water, 10 meter visibility but we’re trained and equipped for it > **[Scapa Flow : Historic Wreck Site](http://www.scapaflowwrecks.com/)** > > Explore the historic wrecks of Scapa Flow, with 3D 'virtual dives', interactive maps and definitive information on the amazing marine archaeology and wildlife ---
**Author:** ![Blakeyrat](https://avatars.discourse-cdn.com/v4/letter/b/ecd19e/32.png) [@Blakeyrat](https://boards.straightdope.com/u/Blakeyrat)\ **Post date:** [July 2, 2013, 6:56pm UTC](https://boards.straightdope.com/t/wwi-german-mine-layers/662453/4 "2013-07-02T18:56:10Z")
> [@Jackmannii](#): > > Don’t know - but isn’t there a risk of unexploded ordnance in Scapa Flow which would pose a risk to divers? > > Sounds like a creepy and cold place to dive. The ships had been surrendered, they weren’t (in theory at least) armed at the time they were sunk. It actually took a lot of work to scuttle the ships without any munitions available, the Germans had been working on it in secret for weeks before the order came. ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [July 2, 2013, 8:38pm UTC](https://boards.straightdope.com/t/wwi-german-mine-layers/662453/5 "2013-07-02T20:38:21Z")
It’s my understanding that the personnel on the minelayer set the length of cable/tether to be spooled out of the base before dropping it off of the minelayer. That way, each base/basket can each be made with the same length of cable by the manufacturer, without having to custom fit a production run to a specific minelaying mission. > **[Naval mine | Moored contact mines](https://en.wikipedia.org/wiki/Naval_mine#Moored_contact_mines)** > > Generally, this type of mine is set to float just below the surface of the water or as deep as five meters. A steel cable connecting the mine to an anchor on the seabed prevents it from drifting away. The explosive and detonating mechanism is contained in a buoyant metal or plastic shell. The depth below the surface at which the mine floats can be set so that only deep draft vessels such as aircraft carriers, battleships or large cargo ships are at risk, saving the mine from being used on a less ... ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [July 2, 2013, 9:21pm UTC](https://boards.straightdope.com/t/wwi-german-mine-layers/662453/6 "2013-07-02T21:21:36Z")
Here’s a PDF on German WW2 mines. See pages 16 & 17, for example. > **[OP-1673A-Ger-Mines.pdf](https://www.ibiblio.org/hyperwar/USN/ref/OP-1673A-Ger-Mines.pdf)** > > 8.71 MB ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [July 2, 2013, 11:08pm UTC](https://boards.straightdope.com/t/wwi-german-mine-layers/662453/7 "2013-07-02T23:08:26Z")
One method was to put a cable drum in the anchor that had a brake controlled by a weight hanging down from the anchor on a pendant (say 10’ long). When the mine and anchor were deployed, the mine would float on the surface as the anchor sank. When the pendant hit bottom, it would lock the drum, and the mine would be pulled 10’ under the surface as the anchor sank the remaining distance.