Difference between revisions of "Diving the Cape Peninsula and False Bay/MV Aster"

Revision as of 06:10, 7 December 2010

The dive site M.V. Aster is a recent wreck in the Hout Bay area on the Atlantic seaboard of the Cape Peninsula, near Cape Town in the Western Cape province of South Africa.

Map showing the positions and features of the wrecks of the Aster (right) and Katsu Maru (left)

Understand

The wreck is easily accessible by a short boat trip, and was prepared for diving before it was sunk. The position is well protected from the south easterly wind, and the depth is conveniently suitable for advanced divers. It supports a large variety of marine life, and is structurally still fairly intact.

General arrangement sketch of the M.V. Aster.

Forecastle of the Aster

Tripod mast

Superstructure looking aft from the forecastle

Divers at the propeller aperture

Position

S34°03.901’ E018°20.967’

S34°03.891’ E018°20.955’ (Mast)

In the middle of the mouth of Hout Bay, near the wreck of the Katsu Maru, about 700m offshore, and just beyond the main traffic lane.

This site is in a Marine Protected Area (2004). A permit is required.

Name

The 340 ton "MFV Aster" was a South African registered lobster fishing vessel which was prepared as a diver-friendly artificial reef by cleaning and cutting openings into the structure before scuttling. It has been used as a training site for wreck penetration. The Aster was scuttled in Hout Bay near the wreck of the Katzu Maru on 9th August 1997.

Depth

Maximum depth is about 28m meters in the scour at the bow and stern at low tide. This may reach 30m at high spring tides. Average depth of the wreck is over 20m. The gunwale of the main deck is at about 24m at low tide, and the top of the mast is at about 9m depth.

Visibility

Visibility will vary from poor to about as good as you will get in Cape Town. 20m is possible, but 10m is more likely on a fairly good day, and less than 5m is entirely possible. The wreck is on fine sand and the visibility is significantly affected by swell. Large or long period swell will keep particles in suspension near the bottom. There is virtually no silting on the exterior of the wreck, but the interior may be silted in quiet corners.

Topography

Flat sand bottom at about 27m. The ship stands almost level imbedded in the bottom as if floating in sand. The bow points towards approximately 330° magnetic (northwest). There is deep scouring of the sand at the bow bow and stern, usually to about 28m maximum at low tide. The vessel is is essentially intact and still looks much like when it was afloat. The hull is intact with a few holes cut in it, and the superstructure is intact except for the wheelhouse, which has lost its forward bulkhead and roof.The tripod mast at the forecastle and the forecastle deck are also intact. There is a fairly large rectangular hatch just forward of the superstructure , leading to a hold, and a winch at each side at the base of the superstructure. The vessel is about 36m long and the beam is about 8m.

The Aster is marked on the charts at the same position as the Katsu Maru and both wrecks can be visited on the same dive. A course of 330° magnetic for about 25m from the port side of the transom of the Aster should put you on the hull of the Katsu Maru quite near the bow.

The layout shown on the map is not necessarily accurate, but is based on the best information currently available. It is possible that the shortest didtance between the wrecks is greater than shown on the map.

Geology: Flat quartz sand bottom.

Conditions

The site is exposed to south westerly swells, which can cause a strong surge. The site is usually at it's best in summer but there are also occasional opportunities in autumn and winter. On rare occasions there may be no surge at all and visibility of over 20m.

This is an area which sometimes has upwellings, caused by strong south easterly winds, resulting in cold clear water, which may develop a plankton bloom over a few days, which will reduce the visibility again.

Keep a lookout for times when the south west swell is low and short period, and there is not too much south easterly wind forecast.

Get in

Access is only reasonably practicable by boat. The site is about a 2.2km ride from the harbour slipway. The wreck is in the harbour approaches, and there may be significant boat traffic.

See

The rare Tasselled nudibranch.

Feather duster tubeworms

Mosaic nudibranch on the rudder

Pair of swimming crabs on the sand

Sponge

A rebreather diver visiting the wreck

The wheelhouse ha lost its top and front

Winch at the front of the superstructure

Marine life

The wreck is heavily encrusted with common feather stars and sponges, with good representation by colonial ascidians and hydroids. The mast has Urchins, black mussels and barnacles near the top. There is a fair range of other species, and the rarely sighted Tasselled nudibranch Kaloplocamus ramosus has been seen here several times. Large rock lobster lurk in the recesses, and rock crabs scuttle around amongst the encrustations of invertebrates. A few small kelp plants have established themselves on shallower parts of the wreck.

Features

Recent wreck in fairly intact condition. The structure is fairly sound and apertures have been cut to make the wreck more diver friendly for penetrations. Most of the structure is clearly recognisable, and all of the exterior is easily accessible for the advanced diver.

Photography

Macro and/or wide angle equipment is recommended. Most of the time macro equipment will give the better results, but on a really good day you may get some fine wide angle shots. Macro will require flash.

Routes

No special route recommended.

• Start deep, progress upward. The wreck is small enough to swim around on a single dive if you just want to see the view. Start wherever convenient, and visit the propeller aperture if you want to record maximum depth. Then ascend to the top of the hull on either side and swim around it at the depth of the gunwale, visiting the main deck and break of the forecastle as excursions. Finish the dive in the shallower parts on the superstructure, or work your way up the mast if not using a SMB or shotline.

• If you wish to visit the Katsu Maru, swim to the southwest from the middle of the port side of the Aster, perpendicular to the length axis of the Aster. It is about 30m away — too far to see even on a very good day — but a large enough target to find quite easily if you are moderately skilled at navigation.

Stay safe

Hazards

Cold water, occasional fog, and boat traffic. Possible entrapment if the wreck is penetrated. Some of the structure may be unstable, and the superstructure has lost a few components. Strong surge is common if the swell is large or the period long, as the vessel lies directly across the prevailing swell direction and a srong surge will create severe turbulence over the weather side gunwale.

Skills

No special skills are required unless penetration is intended. It is necessary to be qualified for 30m dives, so most "Advanced diver" certifications are appropriate.

Equipment

A light will restore colour and allow you to look into the wreck. A reel and DSMB are worth carrying in case it is necessary to surface away from the shotline. A dry-suit is recommended as the water is usually quite cold, but many divers have dived the Aster in wet suits. Nitrox is recommended to extend no-decompression time.

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