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Date: 1943 Type: Blockhouse Status: Extant   Click to view map Coordinates: 33°48'02.40" S 18°22'26.59" E Alt: 5m

INTRODUCTION A set of communication cables was installed to connect Robben Island to the mainland during World War II. These communication cables were critical to integrating the artillery guns on Robben Island into the Cape Town Fortress. The loss of the communication cables would have seriously reduced the effective range of the 9.2" guns on Robben Island, as the Fortress Observation Posts at higher elevation on the mainland would have been taken out of the equation. The entry point of the communication cable onto Robben Island is presumed to be on the beach immediately to the south of Murray's Bay Harbour to the southwest of the southern seawall of the harbour. The cables were placed into trenches dug into the beach sand, in close proximity to the known entry point of the degaussing cable network. It is presumed that the rectangular concrete Blockhouse was constructed to protect the entry points of the communication and degaussing cables. This is the only extant example of such a blockhouse on Robben Island. A similar blockhouse was however built at Bloubergstrand as part of the same underwater degaussing and communication cable installation. ARCHITECTURAL DESCRIPTION The Blockhouse is a rectangular, double-storey, reinforced concrete structure with a flat concrete roof with an undulating cantilevered overhang on all four sides. A notable feature - visible externally at the first floor level of the blockhouse - is the machine gun port on the northeast corner of the building. Smaller steel-shuttered rectangular rifle loopholes also occur at regular intervals on each of the four walls at first floor level. The building comprises two separate rooms at ground floor and a single room at first floor. Entry into the two ground floor rooms is through two single outward opening doors on the east side. The entrance doors are made of steel plates, riveted to heavy angle iron frames. Each door leaf was hung on an angle iron sub-frame using three heavy duty metal pintle hinges. A sliding bolt was used externally to secure the doors in a closed position. The doors could also be secured from within using a sliding bolt mechanism. The sliding bolt mechanisms are now dilapidated. The Blockhouse was provided with two pairs of steel cottage pane inward-opening casement windows at ground floor, each with a pair of outward-opening steel plate shutters. A narrow sloping plastered cill was provided between the steel window frame and the cast in angle iron frame of the external steel plate shutters. The doors and the window shutters are all affected by surface rust but are fortunately still substantially complete. Four sets of two small, simple rectangular openings were provided at high level through the internal face of the concrete wall at ground level to provide natural ventilation when the doors and shutters were in a closed position. Another four sets of similar rectangular openings - but in groups of three openings - were provided on the external face of the wall at high level. These openings were at the same level but were not aligned with the internal openings. This staggered arrangement of opposing groups of rectangular openings was presumably intended to minimise light exiting the building at night under emergency conditions. Each of the external rectangular openings was provided with a louvred cast iron ventilator on the external face of the wall - to prevent the ingress of wind driven rain. The original equipment at ground floor - if any - was presumably removed when the military ceased to have a presence on the Island in 1960. Various 'modern' replacement light fittings exist but all are vandalised. Fortunately the original steel ladder mounted on the internal west wall - with 10 round bar rungs between two parallel flat bar stringers - has survived intact. The metal trapdoor that secured the ladder entry through the first floor slab has however been broken out and removed - probably for re-use by the Prison Service in one of their watch towers. The machine gun port at first floor was placed on the northeast corner overlooking the harbour and was secured with a top hung inward opening steel plate set diagonally across the corner. The steel subframe of this opening had a circular projection on the cill onto which the light machine gun could be supported. A double pitched sloping external cill completed the machine gun port. A small rectangular recess was also provided on both flanking walls to accommodate the two legs of the machine gun. Ten narrow rifle loopholes were provided around the perimeter of the First floor space. Each loophole was provided with a rectangular angle iron sub-frame set flush with the external face of the wall - secured with fixing lugs cast into the concrete. An inward opening hinged steel plate shutter closed each loopholed opening and was secured with a simple rotating catch. An upward sloping internal concrete lintel and splayed internal reveals improved the line of sight. A later timber frame with chicken mesh was installed externally to prevent ingress of birds - albeit that many of these are significantly deteriorated. The concrete walls, the underside of the first floor, and the underside of the flat concrete roof bear clear 'witness marks' of the timber planking that was used for temporary shuttering during construction. The concrete floors were provided with a smooth granolithic finish. The external corners of the building were provided with a broad 45 deg chamfer. HERITAGE VALUE The heritage value of the blockhouse lies in its historical associations with World War II, as an example of a building designed for a particular purpose and function and as an architectural landmark on the coastline of Robben Island. STATEMENT OF SIGNIFICANCE The Blockhouse is closely associated with the defence of Table Bay (and Cape Town) during World War II (1939-45). The building presumably protected the vulnerable point of entry of the degaussing cables onto the Robben Island shoreline. The Blockhouse is a good example of specialised coastal defence architecture. The scale and volume of the structure, the undulating cantilevered roof overhang, the in-situ off-shutter cast concrete finish, and the heavy steel shutters and doors all create a distinctive visual impact. The Blockhouse reinforces the character of the historically important WWII layer present on Robben Island. The choice of construction materials and the robust detailing relate closely to the other reinforced concrete structures built for the military on Robben Island. CHARACTER DEFINING ELEMENTS The heritage character of the Blockhouse resides in the following character-defining elements: The double-storey concrete construction, the heavy duty steel window shutters, the undulating edge to the flat concrete roof, the rifle loopholes, the machine gun port and the steel plate doors. Text compiled by William Martinson, Osmond Lange Architects, with invaluable input and advice from Chris Dooner; October 2019, revised February 2022.