Technology and Operations  
This forum is for discussing technological & operational matters pertaining to U-boats. 
Re: use of AA guns?
Posted by: Ken Dunn ()
Date: December 16, 2016 02:34AM

Hi Heidenreich,

There are a number of scenarios that would cause a lookout to not see a plane until it was too late to dive the boat. Sometimes they just missed it. Each lookout had a sector of the sky to scan & they had to do it for hours on end and that led to eye strain/fatigue etc. Their binoculars sometimes got fogged up, got wet from spray, rain or snow etc. & had to be cleaned leaving their sector to be covered by the other lookouts.

Allied planes were pretty slow at the beginning of the war giving the lookouts time to spot them & dive the boat but as the war progressed the planes got faster but the time to dive didn’t get faster so a plane might be spotted early but the boat still didn’t have time to dive.

Everybody on the bridge and manning the guns had to get below through the same hatch before the boat could submerge but as the war progressed more AA guns were added and there were more gun crew to get below increasing the time it took to dive the boat.

Additionally at some point the allies came up with some paint schemes that made the planes harder to spot even in daylight so they got closer before they were spotted.

Then you have to consider nights, heavy rain, snow, heavy clouds, and fog etc. At night sometimes phosphorescents made the boat easy for the plane to spot even when it was so dark the plane couldn’t be spotted by the boat. Also the relation of the plane to the sun during the day - a plane diving out of the sun was very difficult to spot until it was too late.

The U-boats tried to overcome these problems by installing radar detectors as a radar detector can detect a radar signal from a plane at a range where the signal makes it all the way to the boat but isn’t yet strong enough to bounce all the way back to the plane giving the boat time to dive before the plane can detect them. However allied radar kept one step ahead of the U-boat radar detectors through most of the war so this didn’t provide the desired solution.

Allied planes with cenemetric radar that couldn’t be detected by the U-boat’s radar detectors could spot the U-boats way before lookouts could spot the planes giving the planes time to plan their approach to come in at the best angle given the existing lighting conditions etc. & as the war progressed and the number of allied planes increased dramatically sometimes spotting the U-boat at long range gave the allies time to rally multiple planes to come in at the same time with one trying to force the boat to dive while the next plane attacked as soon as the guns were unmanned and the boat was blind and still shallow enough to be hit with air-dropped depth charges. Tactics and equipment changed on both sides all during the war.

Additionally at some point in the war when a lot of additional AA guns were installed on U-boats they were under orders to fight it out on the surface rather than dive, especially when 2 or more boats were traversing the Bay of Biscay together. That generally didn’t work well either.

Of course a damaged boat that couldn’t dive would have to try to fight it out on the surface.

These are just a few scenarios that come to mind but there were others.


Ken Dunn

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Subject Written By Posted
use of AA guns? Heidenreich 12/13/2016 07:00AM
Re: use of AA guns? Scott Sorenson 12/14/2016 08:17PM
Re: use of AA guns? Heidenreich 12/15/2016 02:22AM
Re: use of AA guns? RandJS 12/15/2016 07:40PM
Re: use of AA guns? Scott Sorenson 12/16/2016 12:08AM
Re: use of AA guns? Heidenreich 12/16/2016 01:56AM
Re: use of AA guns? Ken Dunn 12/16/2016 02:34AM

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