Author Topic: Tores mailbox VIIC and VIIC/41 operation and technical details  (Read 214429 times)

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Offline tore

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I realised I forgot the painting question.
Yes, the frames were painted.
Tore

Offline SnakeDoc

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Hi Tore


Thank you for posting photo with you inspecting the upper deck of the U-995.


If the snortvalve shut,  the big diesel would suck out the air in the sub in seconds and the people would suffer. The cook had a hard time, one minute the kettles simmered in a second it could start boiling like crazy. In my day snorting was a novelty and in order to get experience we were ordered to test out the boat by sailing submerged from the westcoast of Norway passing Iceland to Greenland and back some 27 days submerged, which at that time was a record (in the norwegian navy).

I have found (and translated to polish) instructions for using Schnorchel on type VIIC and IX boats.
http://www.ubootwaffe.pl/okrety/wyposazenie/chrapy.html
(at the bottom of the page there are original ones)


In the one of your previous post you have written:
Quote from: tore
We never operated more than one diesel at the time and always with the propellor disengaged, chargeing the batteries.The other E-motor/generator took care of the propulsion. We tried out direct dieselpropulsion while snorting but learned that the hydroplanes and the boat was not very suitable for high speed submerged and the mast was not designed for the load.


You mentioned the diesel propulsion - I think it is suitable for the case 3 on the page



and the mode you have used is case 5 on page:



From my researches I know, that one 9-cylinder MAN engine created 20 mm Hg vacuum during snorting, but when the snorkel head valve was closed, after 2 min. the vacuum was 120 mm Hg. Did you installed any safety devices shutting off the engines autamatically when such vacuum occured?


You have also mentioned, that the electric distilling plant was not in use on board of the KNM Kaura - how did you supplement the water in battery cells? Where did you get from the water for cooking? You have used the water stored in the tanks for the whole cruise?


Was the navigation a problem during long sumberged cruises? Did you used dead reckonning? Did you use the original german Anschutz gyro compass or you have modern navigation systems?


And one more question not related with snorkeling but related to the sanitary systems - do you know if toilets on KMM Kaura where replaced or they are original/german?


We got a lot of experience and ideas for improvement.
Could you mention improvements you have implemented?


One of the main problems was the garbage of which 46 men produce substancial in the course of 27 days. Rottening garbage is not a pleasant thing and particulary not on board a sub. We got desperate and decided to put it in bags ( before the plastic ages) and load the torpedotubes whereupon we fired. Of course the bags bursted and the torpedopeople didn`t like it much
I have read that during war there were three ways:
1. launching the garbages through the torpedo tubes - not practiced because of necessity of thorough cleaning the tube and hazard of jamming the launching piston during torpedo launch.
2. launching the garbages through the BOLD ejection tube - not preferred bacause of necessity of laborious loading small parts to the tube.
3. storing the garbages on the board - most common.




And one question related to the electric equipment - for a long time I'm looking for the informations about the Batterie Selbstschalter - Battery automatic circuit breakar - located in the galley and near the commanding officer room. I have never seen the photo of such device - and for now I think that the only way is to convince the curator of the memorial in Laboe. Maybe you have some information on this topic?


--
Thanks, regards
Maciek


Offline SnakeDoc

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And one more general question - how did you managed with the spare parts - during operation of the KNM Kaura you have to replace/repair used parts - did the norwegian industry make replacement parts?


--
Thanks, regards
Maciek

Offline tore

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Hi Tore


Thank you for posting photo with you inspecting the upper deck of the U-995.


If the snortvalve shut,  the big diesel would suck out the air in the sub in seconds and the people would suffer. The cook had a hard time, one minute the kettles simmered in a second it could start boiling like crazy. In my day snorting was a novelty and in order to get experience we were ordered to test out the boat by sailing submerged from the westcoast of Norway passing Iceland to Greenland and back some 27 days submerged, which at that time was a record (in the norwegian navy).

I have found (and translated to polish) instructions for using Schnorchel on type VIIC and IX boats.
http://www.ubootwaffe.pl/okrety/wyposazenie/chrapy.html
(at the bottom of the page there are original ones)


In the one of your previous post you have written:
Quote from: tore
We never operated more than one diesel at the time and always with the propellor disengaged, chargeing the batteries.The other E-motor/generator took care of the propulsion. We tried out direct dieselpropulsion while snorting but learned that the hydroplanes and the boat was not very suitable for high speed submerged and the mast was not designed for the load.


You mentioned the diesel propulsion - I think it is suitable for the case 3 on the page



and the mode you have used is case 5 on page:



From my researches I know, that one 9-cylinder MAN engine created 20 mm Hg vacuum during snorting, but when the snorkel head valve was closed, after 2 min. the vacuum was 120 mm Hg. Did you installed any safety devices shutting off the engines autamatically when such vacuum occured?


You have also mentioned, that the electric distilling plant was not in use on board of the KNM Kaura - how did you supplement the water in battery cells? Where did you get from the water for cooking? You have used the water stored in the tanks for the whole cruise?


Was the navigation a problem during long sumberged cruises? Did you used dead reckonning? Did you use the original german Anschutz gyro compass or you have modern navigation systems?


And one more question not related with snorkeling but related to the sanitary systems - do you know if toilets on KMM Kaura where replaced or they are original/german?


We got a lot of experience and ideas for improvement.
Could you mention improvements you have implemented?


One of the main problems was the garbage of which 46 men produce substancial in the course of 27 days. Rottening garbage is not a pleasant thing and particulary not on board a sub. We got desperate and decided to put it in bags ( before the plastic ages) and load the torpedotubes whereupon we fired. Of course the bags bursted and the torpedopeople didn`t like it much
I have read that during war there were three ways:
1. launching the garbages through the torpedo tubes - not practiced because of necessity of thorough cleaning the tube and hazard of jamming the launching piston during torpedo launch.
2. launching the garbages through the BOLD ejection tube - not preferred bacause of necessity of laborious loading small parts to the tube.
3. storing the garbages on the board - most common.




And one question related to the electric equipment - for a long time I'm looking for the informations about the Batterie Selbstschalter - Battery automatic circuit breakar - located in the galley and near the commanding officer room. I have never seen the photo of such device - and for now I think that the only way is to convince the curator of the memorial in Laboe. Maybe you have some information on this topic?


--
Thanks, regards
Maciek


Hi Maciek
Very interesting subject, I just had a very brief look on the German instructions and cannot comment to much on this stage, but it seems to me it refer to the early execution of the snort system. I return to this.
Destilled water. Yes we had containers.
Navigation. I am not a navigator, and cannot comment very detailed on this, but we didn`t have any problem and we used the original Anschutz gyro. When passing Iceland we could of course got bearings. I suppose they used stars when possible and echosounding , but I really don`t know.
Garbarge. One of our experience suggestions was to make a garbage torpedo container to use in the torpedotube. The two other options you mentioned was not not feasible to our opinion.
Experience. A suggestion to operate the diesels disengaged from propellors. Other items was more related to the people and food. For sure there were more suggestions but I can`t remember.
Toilets were the originals
Battery circuit breaker.  I don`t think I have a picture or any notes on this, everything was destroyd some 50 years ago but I `ll have a look. I`ll be back on the rest later.
Tore

Offline tore

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hi Maciek
Futher to your questions.
Dieselopereration during snorting.
We didn`t have any automatic shut down of the diesels at excessive vacum and when snorting the engineer on watch was stand by and had a hard time in bad weather. In fair weather and with a stable trim the underpressure in the sub was not really a problem,it was the variable pressure which caused the troubles.
Drinking- and cookingwater. We used water from the freshwatertanks all the time.
Tore

Offline tore

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Maciek I see I forgot to answer your question on parts.  We had sufficient spareparts from ex german stocks.
Tore

Offline SnakeDoc

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Hi Tore


Thank you for all answers.



Dieselopereration during snorting.
We didn`t have any automatic shut down of the diesels at excessive vacum and when snorting the engineer on watch was stand by and had a hard time in bad weather. In fair weather and with a stable trim the underpressure in the sub was not
really a problem,it was the variable pressure which caused the troubles.
I have read that US subs after GUPPY conversions were equipped with the devices, which shut down the engines when one a large vacuum occured, when the RPM of the engines droped down and when the exhaust gases pressure exceeded. On KNM Kaura without such facilities it had to be really hard work.


Snorting underpressure
We never operated more than one diesel at the time and always with the propellor disengaged, chargeing the batteries.The other E-motor/generator took care of the propulsion. We tried out direct dieselpropulsion while snorting but learned that the hydroplanes and the boat was not very suitable for high speed submerged and the mast was not designed for the load.

What was average cruise speed while snorting? Do I understood correctly, you mean, that accurate depth handling (necessary for snorting) was hard on greater speed?  Or the boat was generally tough to handle?


--
Thanks, regards
Maciek

Offline tore

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Many of the modelbuilders have got confused on the details of the forward and aft steeldecksurface on the VIIC/41,as Revell and some of the PE brass kits shows different pattern. I`m showing the original pattern as on VIIC/41 KNM Kaura ex U 995 and the ex german Uboot pen in Trondheim which became our  submarinestation.
Tore

Offline NZSnowman

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Tore, Thanks for the great picture of the bow  :) :)

From other pictures of the Type VIIC/41 bows I have seen, the steel plate along the edge looks smooth (without the small bump - like my drawing below). I was wondering on KNM Kaura was the steel plate in the centre part of the bow, as it the same pattern and type of steel plate found along the edge?



Offline tore

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Hi Tore


Thank you for all answers.



Dieselopereration during snorting.
We didn`t have any automatic shut down of the diesels at excessive vacum and when snorting the engineer on watch was stand by and had a hard time in bad weather. In fair weather and with a stable trim the underpressure in the sub was not
really a problem,it was the variable pressure which caused the troubles.
I have read that US subs after GUPPY conversions were equipped with the devices, which shut down the engines when one a large vacuum occured, when the RPM of the engines droped down and when the exhaust gases pressure exceeded. On KNM Kaura without such facilities it had to be really hard work.


Snorting underpressure
We never operated more than one diesel at the time and always with the propellor disengaged, chargeing the batteries.The other E-motor/generator took care of the propulsion. We tried out direct dieselpropulsion while snorting but learned that the hydroplanes and the boat was not very suitable for high speed submerged and the mast was not designed for the load.

What was average cruise speed while snorting? Do I understood correctly, you mean, that accurate depth handling (necessary for snorting) was hard on greater speed?  Or the boat was generally tough to handle?


--
Thanks, regards
Maciek
Maciek
Of course today the submarines are equipped with all sorts of sofisticated devices. In  the 40- 50- ties most of the submarines were really "divingboats". The latter part of the war was the dawn of the real sub. The VIIC`s was a "divingboat" converted to some extent, thanks to the snortmast, to a real submarine.In spite of all writingdesk instructions we, operating the thing, had to try out (and fail) various ways to get experience to handle the sub.
As far as I remember (nearly 60 years ago) the to run the diesel direct on the propellor some times made the sub a little "ticklish" and hence you to dip the snort valve too much and we exceeded the values ( we didn`t measure same) mentioned in your german instructions  ( we never did see them). resulting the underpressure to become to excessive and sometimes ( very rare) the exhaustbackpressure. It could be we exceeded the speeds mentioned in your german document.
Tore

Offline tore

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Tore, Thanks for the great picture of the bow  :) :)

From other pictures of the Type VIIC/41 bows I have seen, the steel plate along the edge looks smooth (without the small bump - like my drawing below). I was wondering on KNM Kaura was the steel plate in the centre part of the bow, as it the same pattern and type of steel plate found along the edge?



Hi
As far as I remember, all our VIIC `s had a similar executions as Kaura and the pattern of the "studs" was even all over the steeldeck as shown.
Tore

Offline tore

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Maciek
I cannot remember the average snortingspeed we ended up with, we tried a wide range but the end result was a fairly slow speed, 27 days back and forth to Greenland from westcoast Norway should give an indication.
Tore 
« Last Edit: 03 Feb , 2012, 02:20 by tore »

TopherVIIC

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Tore -
That is a surprisingly smooth (to me) looking torpedo launch from the surface! I would have expected more turbidity and bubbles from a surface shot from tube #1.
At first I thought it was a picture showing that someone cast a mooring line forward and it landed in the water! :-)
Cheers
Christopher

Offline tore

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Tore -
That is a surprisingly smooth (to me) looking torpedo launch from the surface! I would have expected more turbidity and bubbles from a surface shot from tube #1.
At first I thought it was a picture showing that someone cast a mooring line forward and it landed in the water! :-)
Cheers
Christopher
Christopher.
This is a dummy torpedo launched rigth outside the submarinepen. It`s a test, the whole idea is to ascertain that no traitorous bubbles escape from the launch. The torpedo is not running thus leaving no trails, but surfacing immediately after the launch. See picture below.
Tore

Offline NZSnowman

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Tore, Thanks for the great picture of the bow  :) :)

From other pictures of the Type VIIC/41 bows I have seen, the steel plate along the edge looks smooth (without the small bump - like my drawing below). I was wondering on KNM Kaura was the steel plate in the centre part of the bow, as it the same pattern and type of steel plate found along the edge?



Hi
As far as I remember, all our VIIC `s had a similar executions as Kaura and the pattern of the "studs" was even all over the steeldeck as shown.
Tore

Thanks Tore, I will update my drawings.