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U 47 Modifications & Colours

Part III - Wooden deck colours

The colour of U-boat decks has been a puzzling subject for many modellers and enthusiasts. The horizontal deckcasing was made of thin steel, over which wooden planking was applied. The primary reason for using wood was that a metal surface ices up much more quickly in freezing weather than wood. Teak was too expensive to be used, so cheap local wood was used in its place. This explains why the wooden decks on U-boats did not exhibit the silvery appearance of weathered teak.

The March 1940, November 1941 and July 1944 editions of Allegemeine Baubestimmungen Nr.31 (building regulations form Nr. 31) all state that the wooden deck was treated with a black wood preservative (Teerfirnis Tf 99). A U-boat deck started out as jet black in colour then quickly became charcoal in colour. As it was exposed to the elements, the deck developed a brown tinge. The more the deck was subjected to weathering, the lighter and browner it became. On the surfaces that were frequently walked upon, the wood preservative would wear more heavily and reveal more of the natural wood beneath. The deck would also become bleached by saltwater and the sun, causing small patches of white to appear. If a U-boat had not been serviced for many months, green algae would start to grow on the deck. As this plantlife was slippery, and therefore hazardous to the sailors walking on deck, the algae would not have been allowed to accumulate. It would have been removed before any serious built up took place.

In this photo, taken in Kiel in late October 1939, it can be seen that the area under Prien’s feet has worn more heavily than other areas that were not walked upon as frequently. The areas of heavier wear would have been slightly browner.

The extreme bow and stern sections were not covered with wood; they were either painted the same black or dark grey colour as was used upon the watertight hatches and the square-shaped hatches, or with the “upper colour” used on the conning tower and upper hull. These metal areas were prone to rusting, whereas the wooden areas obviously were not. The watertight ready-use ammunition hatches and some of the square-shaped hatches on the deck were also not wood but metal. These were usually painted black or dark grey to match the treatood.

Part IV - Miscellaneous colours

Part IV - Miscellaneous colours: (A) Conning tower

Spray deflector – When the spray deflector was extended in late October and early November 1939, it was painted black. Before this date it had been Dunkelgrau 51. The upper half of the fairing in front of the conning tower (which housed the magnetic compass) was often painted black or dark grey on Kriegsmarine U-boats, but this was not the case on U 47.

Wooden tower floor – The floor area behind the UZO was wood, and coated with black wood preservative. The area of the floor which was ahead of the UZO was metal, and painted black or dark grey.

Wooden slats – The vertical wooden slats on the inside of the conning tower bulwark prevented the crewmembers from sticking to the bulwark metal in freezing temperatures. These were coated with the black wood preservative used on the wooden decking.

Inside of bulwark – The inside walls of the tower bulwark were the same grey as the outside of the conning tower.

Vertical stripe behind rungs – Some U-boats, especially those involved in training, had a rectangular area surrounding the area behind the rungs on the tower sides painted black or dark grey. However, this did not feature upon U 47.

Conning tower base - A thin black or dark grey strip was painted around the base of the conning tower.

Lifebelt – A red horseshoe-shaped lifebelt was sometimes in place when a U-boat was manoeuvring in port. It would be held in place by a bracket on the outside of the tower bulwark. Only in pre-war photos of U 47 can this lifebelt be seen.

Starboard navigation light – Clear green.

Port navigation light – Clear red.

Rear navigation light on tower – Clear white.

Tower railings – The same grey as the conning tower.

Tower railing seats – These seats were made of wood and coated with the wood preservative. The inside edges of the seats were prone to wearing away and revealing the wood underneath.

Periscopes – Grease marks (usually vertical) from the raising, lowering and swivelling of the periscopes were often visible on the stainless steel shafts. The tops of the periscopes were grey.

UZO – Uberwasserzieloptik (torpedo aimer) – From bottom to top - the base was grey, the compass heading ring was bronze, and the azimuth ring was black. Above this, the top removable part upon which the removable binoculars would sometimes sit was grey. Since it was removable and often kept inside the U-boat, this top part was usually less weathered than the tower bulwark.

Inside of tower hatch – White with a red circular handle. The circular rim which is visible when the hatch is open was bronze.

Commander’s flagstaff – This was often located on the starboard bulwark of the tower when U 47 was in port. It may have been Dunkelgrau 51 early in the boat’s career. When U 47 departed upon its final patrol on the 20th February 1941 it was white or the light grey Hellgrau 50.

DF aerial – The circular direction-finding aerial was located on the top of the right hand bulwark of the tower. It was black with a grey top and bottom, and an unpainted bronze stem.

Engine repeater dial – This dial was located at the front of the tower bulwark, ahead and to the left of the UZO (the torpedo aimer). It had black outsides and white insides.

Megaphone – A megaphone can sometimes be seen sitting on top of the UZO in some photos. This seems to have been silver in colour.

Part IV - Miscellaneous colours: (B) Armament

88mm deck guns – The barrel, breech housing and main mounting body of the deck gun were all painted the same grey as the conning tower. The base of the barrel (this was above the recoil tray), which slid back into a sleeve when the gun was fired, was heavily greased.
The ring behind this, which acted as a guide for the barrel when it recoiled, was an unpainted metal which may have been bronze. The U-shaped padded gunlayer’s harnesses were either artificial leather painted black or waxed canvas. The adjustable stems below were stainless steel.
The circular control wheels were painted black on the outside and grey on the inside. The handles for the control wheels were wooden, and presumably coated with black wood preservative. The ring above the base (below the main mounting body), upon which the compass headings were marked, was an unpainted metal, perhaps bronze.

20mm Flak gun – The adjustable stem, which allowed the height of the gun to be altered, was stainless steel. Grease marks from raising, lowering and swivelling would be visible. The padded shoulder supports may have been artificial leather painted black or grey or waxed canvas. The barrel was gunmetal, and everything else was grey. When the 20mm Flak gun was mounted on the aft deck, a thin black strip was painted around the 20mm mount.

Part IV - Miscellaneous colours: (C) Hull

Depth markings – Three sets of depth numerals were marked upon both sides of the hull. These small white numerals were aligned vertically. The top numeral, 9, started roughly at the division between the two greys, and the markings continued down the hull to the bottom numeral, 0. They were situated a few feet aft of the bow, on the saddle tanks, and a few feet forward of the stern.

The front set of depth numerals on the port side stand out in this late October 1939 photo of U 47.

GHG (Gruppenhorchgerät – group listening apparatus) - These were acoustic listening devices that looked like a series of dots arranged in a semi-circle above both of the bow plane guards. They were bronze and usually left unpainted.

UT (Unterwasser Telegraphie - underwater telegraph) – The underwater telephone transducers consisted of two circles above the hydrophones, and two a few feet to the rear of the first pair. There were eight in total - four on each side of the hull. As with the GHG, they were bronze and usually left unpainted.

Propellers – Early U-boat propellers such as U 47’s were made of bronze. Bronze propellers are bright and shiny when new, but turn darker and lose their shine with age. A slight greenish tint can accumulate in the corners.

Propeller shafts - Anti-fouling dark grey.

Part IV - Miscellaneous colours: (D) Deck parts

Bollards – When a U-boat was being moored to a harbour or pier, ropes were attached to extended bollards. The sides of the bollards were usually grey, and the tops were the same black or dark grey colour as the metal parts of the deck. The sides would often be rusty because the ropes would wear away the paint.

Capstan – This retractable electrical winch was situated on U 47’s forward deck casing. The sides were grey and the top was the same colour black or dark grey as the metal parts of the deck. The sides would often be rusty because the ropes would wear away the paint.

KDB – (Kristalldrehbasis Gerät – rotating hydrophone array) – The stem was grey, or possibly red.Wooden poles on deck – These would usually be painted with the same black wood preservative as was used on the wooden deck.

Rear navigation light – Clear white.

Inside of galley hatch – White with a red circular handle. The circular rim which is visible when the hatch is open was bronze.

Insulators – These porcelain insulators were attached in groups of three to the jumping wires, and prevented electricity in the wires from short-circuiting on the metal parts of the deck. They were either brown or bottlegreen. One either side of each group of three insulators were tension adjusters, and these were grey.

Jumping wires – Unpainted steel. In port, the wires were sometimes charged with electricity. When the wires were carrying current, a yellow plate with a red lightning flash hung from fore and aft cables to warn of the threat of electrical shock.