Tores mailbox VIIC and VIIC/41 operation and technical details

[Raymic1]

Fyi
You could also ask that question as well on the curators Facebook site if no one is sure.

Freundeskreis U995

http://Https://m.facebook.com/pages/category/Monument/Freundeskreis-U995


Fyi. I cant seem to get this link to work but just search Freundeskreis U995 on FB.

[NZSnowman]

Hello Mr. Tore and Simon,

Do we have any idea as to what happened to the original U-995 aerial periscope?

Regards,
Don_

I will check my old email from Maciek and see if I can found anything.

[tore]

Don I don`t know but they did a lot on the KNM Kaura ex. U-995 after my time. If the original existing aerial/ navigation periscope was ok it could of course be a spare one for the other VIICs in operation. Such equipment wasn`t easy to get just after the war. In the end of 1950 we were looking for solution of renewing our submarine fleet and as an alternative we looked at modernizing the VIICs which turned out to be very complicated and expensive to that of building new ones from scratch, thus I guess the original periscope possibly was used as spare for KNM Kinn and KNM Kya. KNM Kaura at that time was operated as a training submarine.
Tore

[Don Prince]

Hello Mr. Tore, Simon, and Mark,

To date it looks like there have been well over 1,400 downloads (Subcommittee.com,WehrmachtAwards.com, and numbers unknown from the AMP website) of Skizzenbuch; I am very grateful for all of your assistance in the project. Also there looks to be websites in the UK, China and Russia who are distributing Skizzenbuch with a slow 5 1/2 hour download speed, or a 4 minute download speed for $7.95 to $89.95 (They also distribute many other Copyrighted books; most likely ***Pirated***).

I have been working on an Addendum Booklet for Skizzenbuck to post corrections, and I have had input from one reader where I corrected 2 Type-o's in Skizzenbuch on page 479 in a drawing which could not be checked in Word. These type-o's will be in the CD that I sent to you all (Sorry about that)! If you all have any suggestions for the Addendum Booklet, or corrections for Skizzenbuch, then please let me know...

My time has become more available and relaxed (I still have an upcoming stress test after my heart attack and possible Robotic Bypass). I have restarted working on "Skizzenbuch: U-Boat Type IX C Project" and have a rough draft of about the first 100 pages... Any input would be highly appreciated, and I plan on posting conversations on this forum...

Regards,
Don_

[Don Prince]

Hello Mr. Tore,

Additional research...

The Norwegian Navy got U-4706 Knerten a Type XXIII U-Boat in October 1948, and in April 1950 transferred/used by the Royal Norwegian Yacht Club for storage. She was stricken in 1954 and broken up. This is possibly where the Type XXIII Attack Periscope came from that was installed into U-995 Kaura. So possibly, U-995's Aerial Periscope was damaged while used for training and it got replaced with what was available at that time.

What do you think?

Regards,
Don_

[Don Prince]

Hello Mr. Tore,


Are all the images in this photo of U-995?


Regards,
Don_

[tore]

Don.
The two upper (bad) photos are originals of KNM Kaura ex U995 taken by me during annual drydocking in 1953. The lower photo is details of assumed zinkanodes on my model of KNM Kaura. 
Tore

[Don Prince]

Hello Mr. Tore and Simon,

I was wondering why we have not seen zinc anode plates attached to the protective structures ahead of the bow hydroplanes. I've seen images where the forward protective structure has eroded away/gone from the aft tip (bow) extension where the hydroplane actually pivoted in the structure.

"Iron is also the most corrosion-prone material when it comes in contact with air and water. A ship is continuously in contact with water and moisture-laden winds which makes it highly susceptible to corrosion. The outer body of the ship (mainly hull) is continuously in contact with water, making it extremely vulnerable to corrosion. It is for this reason sacrificial anodes are used to protect the parent material."

The above article talks about winds and the anodes are in the aft section with a huge propeller. Does the prop create the moisture winds which induce the corrosion - electrolyses process and thus requiring the zinc anode plates?

It looks like the zinc anode plates were only used to protect the aft hydroplanes, rudders, and the support structures. Also, none on the hull or the bridge, and I have seen quite a few photos of the bridges just rusting away... Were the U-Boats not believed to survive the war long enough for rust/corrosion to be a problem?

Regards,
Don_

[tore]

Don.
The stern of a VIIC has a great numbers of materials with different potentials which might cause heavy corrosions if not protected. The idea of zink anodes is that you protect all these different materials by introducing a sacrifice anode protecting all these different alloys, hence Zink is used for anodes. The anodes are placed for an optimal protection for the various materials, at hydroplanes, rudders, A-brackets and propellers. In order to have an optimal contact, the zink should be fixed to the item to be protected by ensuring the best possible metallicsurface contact hence bolted, or tack welded to a steel strap casted in the zinkanode,  no paintings on the surfaces. In addition to galvanic corrosion the area suffered cavitation corrosion primarily pittings on the propeller blade roots, caused by bad propeller flow. The bad flow created small vacuum bubbles rapidly filled with steam. The eventual implosion of the vapour bubbles caused noise and the implosions extracted small cavities in the propeller material.   Galvanic corrosion can create substantial damage at strange places, hence placing of the protecting anodes might vary substantially and same are sometimes placed according to experience. F.i. when a standard propeller of special metal alloy is changed by a cast steel propeller, the placing of the zink anodes would possibly have to be changed, hence you would have a number of anode locations on various VIICs.

Finally if you have a closer look at the old U 995 you shall see  deep corrosions in the pressurehull. Some modelbuilders have taken great effort in copying same. These are galvanic corrosions due to negligent of maintenance and possibly  hostile environment (pollution) for years. With such a pressurehull the U-995 would not be fit for a frontline submarine during the war.

In my time we used Zinc chromate a yellow painting as a anti corrosion painting and not zinc anodes in the ballasttanks etc.
Tore

[Don Prince]

Hello Mr. Tore,


Has the COVID-19 Virus shutdown Norway like the rest of the world? Maureen and I, just went grocery shopping and most food items have been restocked, but paper towels, toilet paper, and sanitation products are not available as of yet. How about your location...


Regards,
Don_

[tore]

Don.  We are indeed shut down, As my oldest son was traveling in Kenya we were kept busy getting him home, he is now in quarantine for a couple of weeks, we are in quarantine, voluntary in our home, as we are classified as belonging to a risky group, mainly because of age. In all, this country was reasonably well prepared so we have currently a low deathrate, only 20 in a population of 7 million. I never understood the great demand for toilet paper during crises like this. We order all our groceries by phone and get it outside our door, we dont`t even see the delivery guy. Good old U 995 KNM Kaura would be the place to be right now.
Tore

[Don Prince]

Hello Mr. Tore,

I have attached four (4) photos of the Bow Ice Shield which is used to protect the torpedo tubes in Winter Arctic waters when iced over. It looks like they could release the three (3) front cables and use the last cable to retain the shield. It looks like the last cable uses the bow cleats near the deck edge and the bollards to hold the cables and retain the shield. However, this is just a guess on my part and I can not seem to find and description/data just these photos on the internet...

Regards,
Don_

[tore]

Don, Simon, Dougie47 and others.
 In my time we operated from the German built submarine pens in Trondheim. The pens were primarily built for submarine operation towards the convoys heading for Murmansk. We mainly used one of the 2 pens and the access to the pen was normally covered with ice during the winters. I never saw anything like the bow ice protection shown on your images, neither in the stores, nor in the workshops. We had continuously a small tug/icebreaker keeping the access open. I can not imagine they used this cumbersome rattling devises on their frontline submarines, I should imagine this was, as previously said, probably used for training boats operating out of northern German harbours. Below an image showing the normal winter condition in Trondheim, I guess you are able to see the small harbour tug/icebreaker as well as KNM Kaura ex U 995 entering the pen after returning fra an artic mission in winter 1953. Normally the open waters north of  North cape and Murmansk were ice free except a few narrows and harbours.
Tore

[tore]

Don, Simon,Dougie47 and others.
Come to think about it. There were special missions like erecting automatic weather stations for submarines  frequently in the icy waters of artic like, Canada, Greenland and Spitsbergen, IX boats were used and might have been fitted with Iceshields. The boats were to my knowledge stripped for torpedoes and might have needed som ice protection when landing the equipment.
Tore

[Don Prince]

Hello Mr. Tore and All,

Attached is a photo from the book "U-BOATS: The Illustrated History of the Raiders of the Deep" by David Miller. The photo Showa a U-Boat Type IXC equipped with an Ice Shield as what Mr. Tore described in the previous posting.

Regards,
Don_