Using my renown to upgrade to a new U Boat
 

In the career mode I have made 4 missions and acquired renown.
I have sailed these missions in the Type IIa Boat. I want to
upgrade to a Type VIIb Boat. I have enough renown to do this.
MY QUESTION: How do I go about this. I got to the screen that
has the missions, crew and logs on it and click U Boats. From this
screen I can view the different U Boats, conning towers etc I can
use my renown on, but from there I can't figure out how to use my
renown to upgrade to the type VIIb Boat. I don't want to sail another
mission on the Type IIa boat, can I snag some help from you seasoned
U Boat Captains on this? Thanks;

Hans

To upgrade your U-boat just go to the upgrade screen, click on the U-boats tab, and then double click on the boat you want from the list on the left-hand side of the screen. (Type VII in your case)

before you start a mission, there is a screen in the "office" where you can select your upgrades to weapons, systems etc.

on the bottom left there will be a list of various u-boat types within your flotilla.

click the type you wish to upgrade to.

If the boat is not available for your flotilla it will not be displayed, you will have to use the phone to transfer to a flotilla which is host to the type of boat you wish to select.

hope this helps.