Difference between revisions of "Diving in South Africa/HMS Birkenhead wreck"
Revision as of 10:22, 9 April 2011
The dive site HMS Birkenhead or just The Birkenhead is an offshore historical wreck on the rocky reef at Birkenhead Rock to the south west of Danger Point, near Gansbaai in the Western Cape province of South Africa.
This is an importan historical wreck for both engineering and social reasons. The vessel was one of the earliest iron steamships, one of the last paddle steamers of the Royal Navy, and the epic story of the wreck is a significant item of British and South African history and folklore. The wreck of the Birkenhead is famed for the story of the soldiers who stood by while the women and children were loaded into the few boats that were seaworthy. There are various tales of heroism and stupidity, and a large number of apocryphal anecdotes about shark attacks and bodies being eaten by huge red steenbras. The engines are still in fairly intact condition, and differ considerably from later triple expansion steam engines which were more or less standardised in general layout for a long time.
This site is in a Marine Protected Area (2004) and a closed area. A special permit is required.
The name "HMS Birkenhead" is the name of the ship wrecked on 26 February 1852 at this site
Maximum depth is about 28m. and the top of the adjacent reef is about (depth)m. Average depth on the wreckage is likely to be about 26m, and the highest part of the wreckage, on top of the engines, is at about 24m.
Visibility will vary, but may exceed 15m on a good day. Visibility at depth may differ considerably from nearer the surface, but you will not know until you dive. Lighting will also vary, and will be better on a sunny day, though the amount of light that penetrates to the bottom is very much dependant on the surface visibility, and depth of the thermocline. The sand bottom reflects light, so those parts of the wreck near the sand may be better illuminated that parts on the darker reef areas.
The large sandstone reef to the south east of the wreckage with a pinnacle at the blinder known as Birkenhead Rock slopes down to about 27m at the edge of the sand, which runs roughly east-west magnetic. The slope of this reef is quite steep to the east, but flattens out a bit where the engines of the wreck lie stached at the edge of the sand.
The bottom is fairly flat to the north of this reef, and is sandy patches and low rock reef with scattered wreckage. To the north the reef starts flat but gets a bit more profile further north, bit never more than about a metre. To the west the reef is low and sandy, with odd chunks of wreckage as the highest points. Reef to the east is scattered boulders with sand between.
The ship ran aground while travelling roughly south-east, and the wreckage is aligned more or less north west to south east, with the stern to the north west.
Much of the wreckage is on or around a patch of white sand, and is concentrated in two main areas:
There are also other groupds of parallel large diameter tubes to the west of this boiler which could be fireboxes from another boiler, and assorted bits of hull structure around this area, but most is not easily identifiable.
Geology: Ordovician sandstones of the Peninsula formation.
More information is needed on what weather conditions are best for diving this site.
Good conditions have neem experienced in December and April, but then again on other occasions in the same months, conditions have been bad.
The site is exposed to wind and swells from south west through to south east, so should be dived when the forecast is for low swell and light winds, as the boat trip will be uncomfortable in a chop.
The site is reasonably protected from northerly winds, but they may produce an unpleasant chop. It is not clear which season is more likely to have good conditions.
Water temperature may range from about 17°C at the surface to 12°C at the bottom, with a strong thermocline.
This is a boat dive, as it is about 1.5km from the nearest shore. The usual access is from Gansbaai harbour at S34°35.041'S E019°20.807'E', where there is a good commercial slipway available to the public.
The alternative launch site at Kleinbaai at S34°36.951' E019°21.348'E on the other side of the Danger Point peninsula is slightly closer, but a less protected slipway.
The site is about 10.5km from Gansbaai harbour, or 8.5km from Kleinbaai slipway.
Marine life in this area includes lots of sponges, colonial ascidians and small sea fans, and there are large numbers of noble corals on the reefs nearby.
Much of the wreck is quite heavily overgrown with benthic invertebrates, but some areas are fairly clean, largely where crustose coralline algae have taken hold, or in a few cases where the wreckage is a copper based alloy. The benthos includes a variety of sponges, mostly fairly small, some small gorgonians, the occasional noble corsl, assorted bryozoans, hydroids, nudibranchs and anemones.
There are large numbers of West coast rock lobster sheltering in the wreckage, and quite a lot of fish. As usual, Hottentot seabream are everywhere, but there are also fair numbers of Red stumpnose, Redfingers, and possibly barred fingerfin. Also seen were Pyjama shark, Janbruin, Roman and Spotted gully shark.
Bryde's whales, jumping Bronze whalers, and gannets may be seen from the boat if you are lucky.
Great white sharks have not been seen recently, but are known to frequent the general area.
Scattered wreckage of a historical wreck of great cultural significance. The wreckage includes remains of the paddle wheels, boiler and engine, which is a very early model and quite interesting in design. There are also a few anchors, cannon and similar generic type artifacts.
The site is fairly deep, and lighting is likely to be poor. The wreckage is generally fairly large items, which require a wide angle lens to fit them in the picture without losing too much detail, and powerful external strobes are recommended. Natural light photos may be acceptable if the visibility is good and the lighting better than usual, but it is likely that not much detail will be picked up. Macro photography will produce adequate results on small subjects, but these are not why you dive this site. You dive here to see the wreck, so try to get some photos of it. You may be lucky.
Video will produce best results with a wide angle lens, and preferably powerful lights.
The wreck site is fairly small, and it is possible to see all the major features on a single dive The recommended places for dropping the shot are near to the engines, at the edge of the high reef, which is relatively easy to confirm with an echo sounder, and as near as possible to the boiler, which is central and therefore makes it likely that a bit of error will not make you miss the whole site, The route description is based on a shotline position near the engines.
If a large swell is running, there will be a break at the rock. This could be dangerous to the boat, and it should stay clear, however in those conditions there may also be strong surge on the wreck and poor visibility. Even on a flat day at low tide the pinnacle will break, and on days when there are soth west and south east components to the swell, both may break at the same time. This may happen sporadically and without warning, so be careful.
The site is near to one of the world hotspots for the Great White shark. This may be considered a hazard, and the reports of survivors indicated that many of the shipwrecked crew and passengers were taken by sharks. Most Scuba divers report that they have seen no sharks during the dive, nevertheless this may not be the best place to dive in low visibility. It is also recommended not to spend a long time at the surface, or to plan to do long decompression stops, as the visibility is often worst near the surface.
There may be slight currents, and the biggest hazard from this is not finding the wreck. These may change over a short period, and can be strong enough to require mild effort to remain in place near the bottom. Currents of this strength may be associated with incoming tide, and deteriorating visibility, and are known to set east on some occasions.
Certification appropriate to the depth will be required by most charter boats. Tha ability to navigate by compass and to deploy a DSMB will be very useful.
This is a wreck that is not easy to get to, so it is desirable to maximise your dive time by using Nitrox. It is also recommended to carry a compass, and a DSM to alert the boat that you are surfacing, so it can pick you up without a long delay on the surface.
Back to Diving in South Africa#Gansbaai