U-711

[Pat]

Jan, interesting pic of the underside of the hatch.  It seems to be a late-war boat much like U-995.

The sideways opening hatches nearest the stern look about what I had surpmised, with one diagonal brace although it's not possible from the pic to tell if the brace is wood or steel.  I'd guess steel but does anybody know?

Further forward there seems to be a hatch that is solid, but in a position that would stop them accessing the spare torpedo at the same time as the torpedo loading hatch is open.  That doesn't make sense!  Or am I looking at it wrong?

Again, there's those rectangular extensions on either side of the casing.  Does anybody know what they are?  I've never seen a pic of them on U-711 (the one I'm building) but they would be very hard to cut off and remake the casing underneath without showing.

Another question.  On this boat, as on U-995, the domed pressure hatches for the inflatables are exposed on top of the deck.  But on U-711, even though the domes aren't there, there are wooden hatches in about the same locations.  Are these wooden hatches just an older version of the stowage for the inflatables?  And if so, why did the hatches move up to the open deck later on?  Was the reason that the early inflatables were smaller?

Also, FYI for people, I've seen a couple of pix of the portside at the bow (sorry, I can't find them again) where there seems to be a flat sheet of metal behind the drainage holes going from the start of theinflatable hatches to the back end of the inflatable hatches.  (holes 10-17).  I have not seen anything similar on the stbd side.  The only thing I can think of is that this flat sheet must be a sort of container for the inflatable pressure canisters, probably as something to make it slightly more hydrodynamic under the deck.

The flat sheet seemed to be the same colour as the outside casing, because it would be very easy to see. 

However, I've seen other boats that do not show this flat piece of fairing.  Either it just painted a darker colour on some boats (the same as the underwater parts of the hull?) and thus didn't show up on photos, or it was something that not all boats had for some reason.  (Maybe the inflatable canisters were all separate and less hydrodynamic in those boats?)

Any comments?

[Rokket]

very nice detail!

[NZSnowman]

Again, there's those rectangular extensions on either side of the casing.  Does anybody know what they are?  I've never seen a pic of them on U-711 (the one I'm building) but they would be very hard to cut off and remake the casing underneath without showing.

I asked the same question late October. Check out the reply I got over at Uboat.net
http://www.uboat.net/forums/read.php?14,81381,81381#msg-81381

[NZSnowman]

The sideways opening hatches nearest the stern look about what I had surpmised, with one diagonal brace although it's not possible from the pic to tell if the brace is wood or steel.  I'd guess steel but does anybody know?

I do not know for sure but I imagine it will be made of wood as I think it would be easier to make the whole hatch out of wood   

[NZSnowman]

Further forward there seems to be a hatch that is solid, but in a position that would stop them accessing the spare torpedo at the same time as the torpedo loading hatch is open.  That doesn't make sense!  Or am I looking at it wrong?

No you not looking at it wrong. One hatch opening inward and the other opening to the bow. The torpedo loading hatch would only overlay a small bit over the spare torpedo hatch. It hard to see from the drawing below but the blue arrow show the opening side

[NZSnowman]

Another question.  On this boat, as on U-995, the domed pressure hatches for the inflatables are exposed on top of the deck.  But on U-711, even though the domes aren't there, there are wooden hatches in about the same locations.  Are these wooden hatches just an older version of the stowage for the inflatables?  And if so, why did the hatches move up to the open deck later on?  Was the reason that the early inflatables were smaller?

Yes, the wooden hatches are just an older version of the stowage for the inflatables. I believe there were no pressure container under the deck, but I am unsure how the inflatables were stored 

I also believe all Type VIIC/41 had the pressure containers and only a few Type VIIC had them.

[NZSnowman]

Also, FYI for people, I've seen a couple of pix of the portside at the bow (sorry, I can't find them again) where there seems to be a flat sheet of metal behind the drainage holes going from the start of theinflatable hatches to the back end of the inflatable hatches.  (holes 10-17).  I have not seen anything similar on the stbd side.  The only thing I can think of is that this flat sheet must be a sort of container for the inflatable pressure canisters, probably as something to make it slightly more hydrodynamic under the deck.

The flat sheet seemed to be the same colour as the outside casing, because it would be very easy to see. 

However, I've seen other boats that do not show this flat piece of fairing.  Either it just painted a darker colour on some boats (the same as the underwater parts of the hull?) and thus didn't show up on photos, or it was something that not all boats had for some reason.  (Maybe the inflatable canisters were all separate and less hydrodynamic in those boats?)

Any comments?

Not a 100% what this flat sheet of metal look like, but if you find the pictures again, post them as I would be keen to have a look.

[Pat]

I've been looking for the pictures again for over a year and haven't seen them.  Perhaps the light has to be coming from just the right angle to make the sheet show up.  It looked like it was perhaps a foot inside the casing, and as I said, because it goes from the start of where the inflatable hatches start and ends where the hatches end, it makes sense that it has something to do with the inflatables.  Boxing all the canisters in to make them more hydrodynamic makes sense, but of course to do so it would have to have drain holes since it wouldn't be pressurized.

[NZSnowman]

I will look at my pictures and see what I can found.

[NZSnowman]

Pat, I had a look at all my pictures on my computer, but didn't find anything I will check all my books over the next few days.

[Pat]

Yeah, I know it's hard to find pix of that metal sheet.  I've only seen it twice and as I said, not sure if it was because of the angle of the light, or if it was a rare modification (perhaps a skipper's own prerogative?).

As for the rectangular bumps on each side of the casing near the bow, I follewed your link to U-boats.net and saw your question, but no answer.

There used to be an old Kriegsmarine U-boat crewman working at a yacht club two towns over from me.  I wonder if he's still alive, still there, and might know?

[NZSnowman]

Whose 'rectangular bumps' are likely some item for reinforcing something but I think they will go into the list of items that we do know that they do on a u-boat, just like the two small bump near the bow.

[Pat]

Hmmmm, they don't look like reinforcing and it seems an odd place to need something like that.  Reinforcement would be done inside the casing to be more hydrodynamic and you'd think they'd just redesign the weak section.

I've also seen some of them where the corners are rounded off, more like the fairings over machine guns on some aircraft wings.

[NZSnowman]

I think the reinforcing is on the outside because of the schnorchel on the port side of the boat and the bollards on the starboard side. This is why we think this reinforcing is only on the boats with the schnorchel. Maybe the rounding off was a quick way to make it more hydrodynamic     

[Pat]

Hmmm, I hadn't thought to check to see if the bumps were only on schnorkel boats.  That IS a possibility.

But even still, it might be something to do with the lifting mechanism (not sure how though) but I still don't think it's reinforcing because they're always on BOTH sides and reinforcing would only be required on the port side (for type VII's) or the stb side (for IX's), but not on both.

Also, I can't think of any reason to need reinforcint there because it's the deck that's affected by the snort, not the sides. and reinforcing would make more sense inside the casing/under the deck, not on the outside.

Back to the metal sheets, since you said that the inflatable canisters were only seen on the VII C/41's and later, perhaps the inflatables for the earlier boats were kept inside a metal box that wasn't pressurized, but just enclosed to keep the inflatables in place?  (with appropriate drainage holes).