I've wondered the same thing... I suspect the only way it could be done is to end your current career, and start a new one in Commander and use your old 1WO's name as the name of your new kaleun. You could choose the same flotilla, the same boat number, and a start date that would make it look like you transferred out and he took over the boat. But I think you would start out with a whole new crew for the new kaleun, I don't think there's any way to rollover the crew you had.

Altho I wonder if it's possible to manually edit your existing career files to change the kaleun's name for that career to the 1WO's name? Oh but then he wouldn't be starting out a new command with patrol 1, he'd just "inherit" the previous kaleun's history. So that wouldn't work. :hmmm:

Edit: just popped into my head that even with example #1 above, your old 1WO would lose his rank when you started a career with him as a commander (assuming he was an Obtlt - he'd be "demoted" back to the default starting rank of Lt). He'd also lose all the awards he'd earned serving under you (or that he had when he joined your crew). Those you could give back to him by manually editing his career files after the first patrol but his personnel file would show that he earned them all at the same time, i.e. after completing his first patrol as a commander of your old boat. Which would kind of kill the realism angle for me even more than the entire existing crew being replaced.

Actually, it is really easy to transfer the old crew into the new boat. Especially with SH3Cmdr ... And it is also fairly easy to edit the career files so as to show a true progression from Seekadet to his current rank - including those he "earned" under ya'll. Ditto for awards - many threads on here on customizing said files.

All true, but I understood the question to be completely different:

I have a career under a skipper named Adelbert Ames. SH3C retires him,

His 1WO is Bob Bumpkis.

How can I promote Bob and give Bob the same boat and crew?

That's exactly the way I did it :) Apart from the boat number, my Ex-WO Kessler is now in command of a brand new VII-C.

[edit]A "promote an existing officer"-feature would be great, but SH3 Commander doesn't offer that so it's all imagination :)

I'm wondering now, though, how often it was that an 1WO would be given immediate command of the boat he's already on when the existing commander retires or is transferred ashore... didn't an officer getting ready to take his first command have to go ashore for additional "commander training" first? If so, it seems unlikely that a boat and its already experienced crew would be held in base just to wait on a new commander to do that and come back to take over.

Or was the necessary commander-specific training already completed at some earlier point in a line officer's career? I don't know why I've got it in my head that an officer who was ready for a command had to go ashore for additional training before being assigned his own boat.

I'd go with your second option. Also the 1WO would have had some experience observing the previous command so probably would know how to do a lot of the stuff he did.

A "Baubelehrung" (Final stage of construction accompanied by future crew members to introduce them to technical details, equipment etc.) of a new UBoat took 4-8 weeks, usually 3-6 months before the boat moves out for the first patrol.
Since my ex-WO is pretty familiar with a Type VII-C I guess he doesn't have to attend the whole "Baubelehrung" ;)

But how this was handled in real life back then - I 'm not quite sure about that.
Maybe I should browse through the profiles/biographies of some UBoat-Commanders to check this.

[edit] In the case of "Engelbert Endrass" - he was 2WO on U-29 from October 1937 to January 1938, after that 1WO on U-47 from December 1938 until January 1940, then taking command of U-46 (VII-B) from May 1940 until September 1941. Finally he take command on U-567 (VII-C) from October 1941 until U-567 was lost NE of the Azores in December 1941.
[edit2] "Hansjürgen Hellriegel" was 2WO on U-46 from December 1939 to March 1941 before he took command over U-140 in April 1941.
I guess an immediate detachment as a Cdr of an UBoat was pretty usual for experienced 1WOs oder 2WOs.

From u-boat.net's article on u-boat commander training:
This shows a SOP of having a prospective commander spend several weeks with a training flotilla specifically preparing for his command, after doing his time as a frontboot WO but before being given his own boat.

In Neither Sharks Nor Wolves, author Mulligan refers to this "Commanders' Course" as being the final stop on a line officer's career trajectory from receiving his commission to taking his first command, after completion of which

As noted at u-boat.net the step-by-step process of going from cadet to commander might vary depending on the circumstances, but these sources at least do seem to indicate that accepted SOP was for even an experienced WO to return to a training flotilla for specialized commander training prior to getting his own boat... which makes it seem unlikely that it was common procedure for a boat to just be turned over to its existing 1WO when the current commander was taken off the front line (cases of death or incapacity in combat notwithstanding).