"Gun Holes"

[mark harrison]

Hi-
I am looking for information on what I will call gun holes.
These are the series of holes alongside the casing or sea hull of the Mark 7 boats and level with the 88mm gun.
They appeared on boats that were commissioned between 1940-1942.

I do not know if the commanders chose to have them or the boats were commissioned with them-so does anyone know?

regards MH.

[oldhoweboy]

A picture paints a thousand words, Mark.
Can you offer any help on my three new topics??
Rgds
Nobby

[ChristopherPerrien]

Do you mean the "Vents or Vent Holes"? They allowed "air" between the outer hull and the pressure hull and in the ballast tanks, to escape so the sub could submerge.

From wiki, these holes?

[mark harrison]

HI What I am asking about is the line of round holes on the hull along the front part of the railings.
These are I believe designed to reduce the water pressure under the deck gun and stop water exiting upwards toward the gun crew.
They are not part of the subs trim or ballast systems.
But not all boats had them and I wish to know wether the boat was launched with them or were they added later.
Early picture of U 552 does not show them but later ones do, most commissioning pictures do not have them.

So any info on these holes will be welcome.
Regards MH.

[ChristopherPerrien]

They look like more vent holes. I would guess to immediately vent off an "air-pocket" that formed in that area/void. You don't don't want any bubbles, minutes after you submerge.

[mark harrison]

Thanks for the reply. I've had internet problems and cleared them a few days ago.

What I am trying to do is see if I can use these holes to date the commission of the boats or at least around about the period they were completed.

Regards MH.

[Åkerberg]

[mark harrison]

HI, Thanks for the picture these are what I meant. Gun holes can sometimes confirm or deny the ID of a boat.
There used to be a picture of a boat coming into Bergen claimed to be U 255 which did not have Gun holes nor did it have the gap between the fuel tanks
and the hull as wide as this one above. I think it was U 334.

Thanks again for this and the speaker info in a previous post-now I can ID boats from behind too.

Regards M H.

[Åkerberg]

Hello!

According to Dougie Martindale article "List Of U-Boat Modifications & Indentification Features" (only published in spanish at www.u-historia.com)

Curved line of vents
These vents, directly above the central drainage area in the area vacated by
the breakwaters, differed between boats

[mark harrison]

Hi,Once again thanks.
Regards MH.

[mark harrison]

Hi, A last word on gun-holes as far as I can determine they were used on boats that were commissioned between August 1940 until May 1942.

Regards MH.

[Åkerberg]

Now you can found the article I mentioned in english:

Go to: http://amp.rokket.biz/lib_uboats.shtml

And download: List Of U-Boat Modifications & Identification Features (1.0Mb)

[oldhoweboy]

Thanks Danni

[mark harrison]

HI,

Just spotted new thread thanks again.

M Harrison.