Kriegsmarine U-boats were painted in two greys. The first grey was painted on the conning tower and the upper hull (above the waterline). The second darker anti-fouling grey was painted on the lower hull, below the waterline. The horizontal division between the two greys took place just below the free-flooding holes on the hull. Early pre-war boats had this division line slightly lower than was common during the war. Some pre-war original Type VII boats (also known as VIIAs) had the tops of their saddle tanks painted in the upper colour, but most Type VIIs had the whole of their saddle tanks painted in the lower anti-fouling colour. Contrary to many illustrations in numerous publications, there was no bootline/boot-topping (the dark grey horizontal stripe between lower and upper waterline) on U-boats; these were only applied to surface units. The steel horizontal surfaces at the extreme bow and stern were either painted in the upper lighter grey or black. The wooden deck was coated with a wood preservative, and shall be discussed later.

Lower hull colours

A number of side profiles, drawings and illustrations show U-boats with red lower hulls and black bootlines, and these have sparked countless debates within the modelling community. Many commentators maintain that no U-boats, either before or during the war, ever had red anti-fouling paint beneath the waterline. Another opinion is that at the very start of WWII some U-boats had red lower hulls, but at the next dry-docking they were painted dark grey. Other opinions hold that while some pre-war boats may have been red, all wartime boats were dark grey.

In the book "Die Deutschen Uboote Geheim 1939-1945" (German U-Boat Secrets 1939-1945) by Richard Lakowski (Brandenburgisches Verlagshaus, 1997), there are two editions of the building regulations form Nr. 31, which specifies the application of paints upon U-boats. These can be found at –

http://www.u-boot-archiv.de/dieboote/farben_maerz_1940.html
http://www.u-boot-archiv.de/dieboote/farben_juli_1944.html

The March 1940, November 1941 and July 1944 editions of this building regulation all state that the external sections of the lower hull were to be painted with two coats of anti-corrosion paint (see “Unexposed colours” section for the colour) followed by one coat of the anti-fouling dark grey paint Schiffsbodenfarbe III Grau (DKM 23a, literally “ships bottom colour 3 grey”). This was called Wasserlinienfarbe W.L. III Grau (literally “water line colour W.L. 3 grey”) in the first two editions, but as previously mentioned this was exactly the same paint as Schiffsbodenfarbe III Grau. Finally, another coat of Schiffsbodenfarbe III Grau (DKM 23b) was to be applied. 23b was exactly the same paint as 23a; the letters were used to specify that two coats were to be applied. There is no mention anywhere in these regulations of Dunkelblaugrau (RAL 7026), which is included in the Snyder & Short paint chip cards and White Ensign Models’ KM paint range (Colourcoats KM03).

The otherwise excellent "Type VII U-Boats" (Brockhampton Press, 1998) by Robert C. Stern includes erroneous information on hull colours which directly contradicts the painting regulations. It is stated by Stern that, “the underbody was supposed to have been painted with a red anti-fouling compound but seems just as often as not to have been covered with the dark grey waterline colour,” and that, “the upper surfaces of the saddle tanks and the band on the boat’s side between normal trim waterline and lightest trim waterline were painted dark grey.” Both statements are unquestionably erroneous: the wartime regulations call for dark grey anti-fouling paint and no bootline. Given the quality of Stern’s book, it is very surprising that he should have made these obvious errors.

The artists who produced the drawings of wartime U-boats with red hulls and bootlines may have been influenced by the standard Kriegsmarine surface unit colours of red-brown hull - Schiffsbodenfarbe III Rot (DKM 22a and 22b, RAL8013, Colourcoats KM04) - and dark grey (Wasserlinienfarbe W.L. III Grau) bootline. Some artists may also have known that dark grey was the real colour used on wartime U-boats, but preferred to opt for red. The red hull provides a much more visually stimulating drawing than the drab, featureless grey, and artistic license may well have negated historical accuracy. The Amati 1/72nd U 47 kit is a perfect example of this. The model shown on the box has a red hull, yet the instructions specify that dark grey should be used. I suspect that marketing considerations may have taken precedence over accuracy.

The wartime painting regulations are thankfully available to us, but the pre-war painting regulations are, unfortunately, not in common circulation. These pre-war regulations would likely have shed light on the question of whether red anti-fouling paint and dark grey bootlines were applied to pre-war boats at any stage. It is especially regrettable because in black and white photographs it is impossible to distinguish with any degree of certainty between a red and a dark grey hull.

Since the U-boat arm had been experimenting with the colours above the waterline in the years leading up to the commencement of hostilities, could it have been possible that they also experimented with the colours below the waterline? A comment by U 35 veteran Kurt Grosser suggests to me that colours other than dark grey were used in pre-war times. He maintains that when he reported aboard U 35 in April 1939 the lower hull of this U-boat was dark green. We should be extremely careful when dealing with veterans’ memories of the colours used 60 to 65 years ago, but this comment is interesting in light of the fact that a green anti-fouling paint - Schiffsbodenfarbe I Grün (DKM 24a and 24b) - was mentioned in the 1944 painting regulations.

If some experimentation had taken place, and it appears that it did, then it may be impossible to disprove the possibility that some pre-war U-boats may have had red hulls. Although there is no positive confirmation of pre-war red hulls, how can we be certain without having access to every edition of the pre-war painting regulations that they did not exist?

There is a colour photograph in existence showing Joachim Schepke holding a toy model of a pre-war U 29 with a thick bootline and red hull. I am certainly not suggesting that this constitutes evidence of the use of red anti-fouling paint or bootlines on lower hulls. The manufacturer of the toy model possibly assumed, just as some people do today, that the red anti-fouling paint in common use upon other vessels of the Kriegsmarine was used upon U-boats. I mention this because I find it amusing that the possible erroneous use of red on U-boat models may have started as early as 1940 or 1941!

Having studied a number of photos of wartime U-boats coming off the slips and in dry-dock, I have not to date seen any evidence of any bootlines on any of these wartime boats. While an appreciable bootline might be difficult to discern in some black and white photographs, I have seen enough good quality images of exposed wartime U-boat hulls to convince me that bootlines were not applied to wartime boats. Neither have I discerned a bootline on any of the photos I have seen of pre-war boats with their lower hulls exposed. Some of these photos are of an excellent quality, and a bootline would certainly be discerned if present on the hull observed. However, I have not seen enough pre-war photos showing exposed lower hulls to be certain that bootlines were not present on some pre-war U-boats.