Dry Docks, Dry Docking and Ship Repair in South Africa

Dry Docks, Dry Docking and Ship Repair in South Africa

This talk is about the sea and ships

But, at times ships need to be taken out of the water

Not this way - though!

That s why Dry Docks were invented

To understand Dry Docking you need to master: Civil Engineering Mechanical Engineering Naval Architecture

There are 3 basic ways to dry dock ships Civil Engineering: Graving Docks & Boat Ramps Mechanical Engineering: Slipways, Shiplifts & Straddle Carriers Naval Architecture: Floating Docks

Slipways

Ancient Ship Sled

Reusing Ancient Technology

Victoria & Alfred Docks c 1870 De Pass slipway top left

2 nd De Pass Slipway, Table Bay

Patent Slip Patented 1819 by Thomas Morton of Leith

Timber Cradle Luderitz ca 1960

Port Elizabeth Slipway ca 1947

PE Slipway 1200 ton Ways Military specs Strong enough for a Panamax Vessel?

Norseman Side Slip

Norseman Repair Yard 18

90 ton Cape-type Slipway, Hout Bay

Modern 200 ton Slipway with 2 Side Slips

Hydraulic Bilge Arms 21

Modern, Large, Underslung Wheel 22

Live Rollers Air Cushion Movers

Crandal Railway Dry Dock

Railway Dry Dock - Construction Note vertically curved ways with live roller trains

Shiplifts

The earliest screwdock, the earliest shiplift, was patented and constructed by Captain Jesse Hurd of Connecticut in New York in 1827

The New York screwdock was suspended from eight screws of 4½ (114 mm) diameter. Capacity about of 200 tons. It was hand operated. It took about 30 men about half-an-hour to raise a vessel 10 feet (3 m).

Barbados Screwdock Built 1893

Barbados Screwdock in 2010

Early Shiplift London Built by Edwin Clark - 1857

Layout, 1750 TLC Syncrolift & Yard Cape Town ca 1975

Platform, Cape Town Syncrolift

Side Transporter Repair Yard

2000 TLC Pearlson Syncrolift Shiplift Walvis Bay, ca 1974

Transfer & Repair Yard Walvis Bay

Wire Rope Syncrolift Shiplift Winch 37

Hydraulic Chain Jacks Bardex Type Shiplifts

Graving Docks

Evolution of Graving Dock X-sections

Robinson Dock Cape Town, 1880

Opening of the Selbourne Dock Simonstown 1910

Elizabeth Dock, East London ca 1947

Sturrock Dock Cape Town 1945

Sturrock Dock Bed for Two Ships

American Dockyard & Graving Dock

Setubal Dockyard

Modern Super Tanker Dock Setubal, Portugal ca 2000

Position for removable barriers Removable barriers to flood Hydrolift portion

Setubal Super Tanker Hydrolift

Hydrolift, Setubal, ca 2000

Modern Axial Flow Pump

Graving Dock Gates

Floating Docks

Camels the Origin of Floating Docks

Basic Types of Floating Docks

8000 TLC Eldock + 4000 TLC NPA Dock, Durban Both ex Russia

8000 TLC Walvis Floating Dock

Crandal-type Transferring Dock

Heavy Lift Vessel used as Floating Dock

Dock Furniture

Leading Mules

Safety Parapet

Rope Handling Furniture

Warping Vessel with Capstan & Bollard

Electrical Power Supply Point

Bilge Support Blocks on Syncrolift

Modern Style Concrete Keel Block with timber base, sand jack and timber capper

Well Managed Keel Blocks

Keel Blocks and Locating Marks

Design Issues

Slipway Ways Geometry

Vertically Curved Ways Built-up Cradle

With a straight grade the relationships are linear. Despite the apparent complexity, the issues are trivial.

Here the system is non-linear and tediously complex to analyse but systems cannot be designed without a full analysis

Sue Loading

Sue Load

Sue Load is given by: S C t Where d m Δ = Displacement δt = Change in Trim d m = Draft midships C is usually about 0.17

Loss of Stability

Keel Block Loading

Crandall Trapezoidal Loading

Lloyds Parabolic Loading for Shiplifts

Lloyds Loading for Floating Docks

Modern Docking Plan

Basic Types of Graving Docks

Floating Dock Stability

Failure Patterns

Slipway Rails

Slipway Rail Corrosion Patterns

Shiplift Ropes

Fatal Corrosion pattern in Shiplift Ropes

Primary Cause: Usually the Bean Counters Shiplift Rope Corrosion

Consequences

Rope Maintenance Dolly

Shiplift Platform Repainting

Reassembling Syncrolift after Repainting

Keel Blocks

Poorly Managed Keel Blocks

Poor Timber Management Keel Block Failure

Bar Keels cutting into keel Block Capper

Graving Docks

Towing Failures Particularly around the Cape

Wreck of Refurbished East London Caisson Gate

Wreck of New Durban Floating Dock

US Navy Floating Dock Failure

Loss of a Customer

Dry Dock Economics

Potential Target Market In the Southern African region the trades are: Cargo Fishing Offshore Diamond Dredging Offshore Oil

Potential Target Market Existing Ports and Repair Facilities What ports are able to accommodate the dock? What workshops and skilled labour are available?

Potential Target Market Existing Ports and Repair Facilities Mobilization Time Frame

Potential Target Market Existing Ports and Repair Facilities Mobilization Time Frame Regional Infrastructure Resources These can vary widely in the Southern African region and have a significant impact on ship repair

Potential Target Market Existing Ports and Repair Facilities Mobilization Time Frame Regional Infrastructure Resources Environmental Issues

This is arguably the most expensive component of dry docking

Need for vessels to carry docking plans

Need for vessels to carry docking plans Cost of preparing block plans

Need for vessels to carry docking plans Cost of preparing block plans Cost of setting blocks

Need for vessels to carry docking plans Cost of preparing block plans Cost of setting blocks Cost of dewatering and flooding to set blocks

Need for vessels to carry docking plans Cost of preparing block plans Cost of setting blocks Cost of dewatering and flooding to set blocks Cost of placing vessel accurately

Need for vessels to carry docking plans Cost of preparing block plans Cost of setting blocks Cost of dewatering and flooding to set blocks Cost of placing vessel accurately Cost of removing and replacing blocks

Need for vessels to carry docking plans Cost of preparing block plans Cost of setting blocks Cost of dewatering and flooding to set blocks Cost of placing vessel accurately Cost of removing and replacing blocks Cost of maintaining blocks

Economic Realities of Dry Docks Income from docking charges is minimal and insufficient to service capital expectations

Economic Realities of Dry Docks Income from docking charges is minimal and insufficient to service capital expectations The money is made in ship repair

Economic Realities of Dry Docks Income from docking charges is minimal and insufficient to service capital expectations The money is made in ship repair Ship repairers cannot afford to cover the capital costs unless they own the dock and gain the capital appreciation

Economic Realities of Dry Docks Hence there are only two viable economic models for the ownership of Dry Docks 1. Ship Repairer owned financed out of the profits on ship repair 2. Public Ownership financed out of the general contribution of ship repair to the economy of the region

Economic Realities of Dry Docks In both cases the Port Authorities must come to the table to treat ship repair as an important regional economic activity and to provide suitable sites for dry docks and ship repair within the harbours.

Offshore Oil & Gas Big-time potential for ship repair in South Africa