The Ton Class This wooden hulled minesweper has a displacement
of 425 tons, 153 ft long, with a beam of 29ft and draught of 8 ft.
Powered by Napier Deltic diesels with a service speed of 15 knots.
At the end of he Second World War it was generally accepted that
the emphasis on mining had shifted from deeply laid moored mines to
ground mines laid in the shallow approaches to ports and harbours.
The large steel-built ocean minesweepers were, therefore, mostly
unsuitable for sweeping sophisticated modern mines laid in coastal
and inshore waters. As a result, a team was formed at Bath in the
UK in 1947 to design the next generation of minesweepers.With the
exception of the double mahogany hull planking, almost the entire
vessel was constructed from light aluminium alloy and other
materials with the lowest possible magnetic field to achieve
optimum safety when sweeping for magnetic mines. They were
protected from pressure mines by their low displacement, and the
threat of moored mines was greatly reduced by their shallow
draught. The design called for an aluminium-framed, wooden planked
hull with non-magnetic fittings, capable of undertaking ocean
passages, and the result was a double mahogany, copper plated and
very sturdy craft which is still in service all over the world.
Constructed of wood and other non-ferromagnetic materials. Their
small displacement and shallow draft gave them some protection
against pressure and contact mines, and allowed them to navigate in
shallow inshore waters. Armament was one 40-mm Bofors gun. Sweeping
equipment was provided for moored mines and magnetic mines.
Minesweepers are equipped with mechanical or influence sweeps to
detonate mines. The minesweeper itself produces much less noise
than other ships, and are often constructed with hulls of wood,
plastic or low-magnetic steel. Mechanical sweeps are towed devices
designed to cut the anchors of moored mines, and preferably attach
a tag to help the subsequent localization and neutralization.
Influence sweeps are towed equipment that emulates ship signatures,
and thereby fools the mines to actuate. Most sweeps focus on the
magnetic and acoustic signatures. There are two modes of operating
an influence sweep: MSM (mine setting mode) and TSM (target setting
mode). MSM sweeping is founded on intelligence on a given type of
mine, and produces the output required for detonation of this mine.
If such intelligence is unavailable, the TSM sweeping instead
reproduces the influence of the friendly ship that is about to
transit through the area. TSM sweeping thus clears mines directed
at this ship without knowledge on the mines. However, mines
directed at other ships might remain. SAS DURBAN was launched on
the 12th June 1957 and arrived in Simonstown on 13th June 1958. It
was one of two minesweepers ordered and built specially for the SA
Navy. The other was the SAS WINDHOEK. These two ships formed part
of the 147 Minesweeping Squadron. As the bloodhounds of the sea the
mine counter measures flotilla could confidently state that "where
the fleet goes we have been". While part of the SA Naval Fleet the
SAS DURBAN had a cheuered history by been commissioned and
decommissioned several times. The Chief of the SA Navy, Vice
Admiral G.Sydercombe, officially handed over the SAS DURBAN to the
city of Durban on 5th May 1988 The reviewer has kindly allowed me
to replace this cache.