Hmm,
it might have help to tell what painting guide you refer too. My S-Boot box has None. You tube or similar?
Let me list what was red on Schnellboote.
The number I use is from the WW II Kriegsmarine Color list.
22 Schiffsbodenfarbe Rot was used on the hull, invisible on the waterline Warlord model. (The waterline was 23 Wasserlinienfarbe WL I Grau dark Grey )
Rescue material like rings and rafts could be painted in Grey but normally for visibility in use 93 Kaiserrot (A Kind of dark orange)
On left side of Bridge the area around the port light was painted red for daylight. (Starbord green)
Some boats had red tactical signs at the Bridge, but theay are few.
Boats in Black Sea had the deck around the bow 2 cm gun painted red and White as aerial markings.
The only other thing red was the Kriegsarine ensign.
But a pipe?
.
