Hello sunhunter,
That is one fine looking boat you got there!
Anxious to see it finished.
If you will allow my imput, the lower hull of all wartime u-boats,
was dark gray (Schiffstarnfarbe dunkelgrau -31 ). It seems to
be a popular misconception that Schiffsbodenfarbes.b. i rot 22a (hull red) was involved.
My sources indicate that some pre-war boats may have been
painted hull red but that was covered over when the war broke
out.
There seems to be no actual records of red lower hulls on
u-boats that went into action.
Hope that this is of some help.
Have a nice day and happy modelling, 
