The Cod might be a rarity. A lot of boats probably got the upgrade after the war, if they were kept around for GUPPY conversions and such.

Btw, Gino, have you been to the new www.submarinemuseums.org website? We don't have a representative from the Cod, yet. Maybe you would like to be the mouth piece for that boat? It will create more visibility of what the Cod is doing/dealing with and it's a great place to swap ideas and stories about boat maintenace and restoration.

Norman Friedman mentions in his book that Mark 3s were upgraded to Mark 4 but doesn't note whether this was during the war or not.

I emailed the guru that keeps the Mk. IV TDC running on the COD and asked him when it was originally installed and if it can be broken down into small enough subcomponents to fit through a hatch. I'll let you know what he says.

Could have asked me that... I would have called him :D

One answer I already know: Even disassembled the TDC does not fit through the conning tower hatch. The PK and the AS are simply too wide for that.
As far as I know, the TDC we have has been in the Cod since commisioning.
That also confirms something I noted on the web yesterday: The Mk4 was introduced in 1943. Cod may have been one of the first to receive a Mk4.
That later boats still received a Mk3 may have something to do with which shipyard built the boat, and what did they have in stock?
Cod was EB built, so I presume that EB, since they are not a governement shipyard, ordered their alotment of TDCs at the last moment. Thus they would have no stock of Mk3's, and thus a Mk4 was built into Cod. Now Pampanito was Portsmouth built. Launched July 1943, Cod was launched May 1943. So, it could be that Portsmouth had a supply of Mk3' that they would have to 'get rid of' first.
That would also go for Batfish, launched May 1943 by Portsmouth shipyard.

However, it doesn't fit when we look at Hawkbill and Icefish who were built by Manitowoc from August/September 1943 and launched in January/February 1944. They had a Mk3 TDC. Also these two were Guppied, and the TDC was not updated to Mk4. It may have been updated to another Mod, but the receiver was never built in. :hmm:

I think we need the support of the US TDC Guru, Terry Lindell. Let me see if I can 'find' him...

groetjes,

Yeah. I'm really curious as to the limited use of that model. Maybe it was a trial program and they wanted to see if there was any added benefit to adding the third input panel. Also, by mid-'43 we were really sticking it to the Japs - sub attacks, specifically. The Navy may have decided that there wasn't a huge advantage, boats were already getting lots of successes with the fixed torpedoes, and they stayed with the cheaper/simpler Mk. III.

Just got of the phone with our TDC-guru (as you call him...)

Well, I couldn't have been more wrong... :oops:
The Cod did receive a Mk3, that was upgraded to a Mk4 after the war.

They would 'only' have to separate the PK and AS from each other and fit in the Receiver unit.
Essentially the TDC remained the same, you'd still have to crank in the basic parameters. The receiver 'units' could be used by selecting the appropriate switch on the Receiver.

Now, what utterly puzzles me is that Cod who never was in the Guppy program did receive the upgrade, but e.g. Hawkbill and Icefish never did.
Must have been a government thing...

So it seems that most, if not all boats, received a Mk3 during ww2. And that some of those boats received the upgrade and others didn't.

Let me get out an e-mail to someone who might know the precise data...

To be continued...

groetjes,

Gino,

Thanks for contacting Paul about this. Our email server at work has been having problems with outside email contacts.

So, Mk. IV was just a mod to Mk. III by adding in the Receiver unit.

I'm guessing that there wasn't widespread upgrades, because by the end of the war and early Cold War days, more emphasis put on active and passive homing torpedoes that could also attack submarines at fairly deep depths (by late '40's standards). Doctrine was starting to move away from visual attack methods and move toward computer and sound assisted attacks.

That is just my 2 cents based on torpedo development history...

I sure hope you don't think that Paul is the TDC-guru... :rotfl:

For this one I went directly to Dr. John. He is the one that taught me how to operate the TDC, that's the guru for me.

Although we now know something about Mk3 and Mk4, I can try to contact the Chief-guru to figure out what happened when, and how... :hmm:

Any specifics we want to know from him too?

groetjes,

So, Paul isn't the guru. Fred Tannenbaum directed my questions to him on the Sub Museums website forum.

For radar input, ask him if the new receiver unit took data from SJ-1, FM periscope radar, or both.

Gino,

Here's what Paul wrote to me:

Since upgrading to a Mk. IV meant inserting the Receiver module between the PK and AS modules, it looks like the Receiver module is narrow enough (based on pictures) to fit through the bridge hatch. So, I think John and Paul are both right, depending on which modules you're talking about.

The Receiver can fit through the hatch. But the PK and AS units won't.
Paul also means the Receiver unit, and not the whole TDC. It would be costly to remove the whole TDC. The upgrade thus would consist of adding the Receiver and modifying the PK.

Yesterday I fired off an e-mail to the TDC-Chief-guru. I put the questions you had also in there.

To be continued...

groetjes,

So, we're all on the same page, now. :D

Yep, took a while to get there, but running straight and normal now :up:

Do you have your TDC running yet?

With the manual on the HNSA website it should be no big thing... :)

Maybe you should invite the TDC-chief guru over to have a look at it. He fixed Cods TDC and got it running in no time.

Fun thing is that two years ago we ran some tests (as described in the manual) and this TDC was still running within specification, even after over 40 years!!!

groetjes,

Our real TDC is in an officer's club somewhere in Pennsylvania (probably Philly). What we have is a plywood mock-up with all of the cables cut and one of the torpedo firing controls removed. :down:

We still have the post-war surface radar and I'd like to get the scopes working, again. First, we need to run 120 and 240 power into the control room. The museum's main concern is repairing the exterior right now.

What type of shore power do you guys have running into the Cod? Where did you run the wiring to bring it on board?

You'd have to ask Paul about that one. I know it's barely enough to run the lights... Even if we would be able to run the airconditioning again, there would not be enough power.

BTW Bummer about that TDC.

As for a working radar, we were thinking to restore our SD to working condition. But some other project needed more attention. Mind that the FDC (?) has to know about this, and you basically need a HAM (or better) radio license to operate the unit.
Cod being close to an airfield might hinder the process, although we are far lower in frequency than the airport radar.

groetjes,