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KNOT BEFORE TIME
Factors affecting the mooring of the Barque Polly Woodside

At the Melbourne Maritime Museum 37 deg. 49' South, 144 deg. 5' East

Kenneth Shewan


TABLE OF CONTENTS

1.0 Disclaimer

2.0 Introduction

3.0 Duke's and Orr's dry-dock

3.1 Location

3.2 River conditions
3.3 Tides
3.4 Siltation
3.5 Water Pollution
3.6 Climate
3.7 Wind
3.8 Table 1 - Table of air temperature, wind speed, rainfall

4.0 Barque Polly Woodside

4.1 Chronological history
4.2 Dimensions
4.3 Register details
4.4 Plate thickness
4.5 Ballast
4.6 Maximum stress
4.7 Ship's equipment
4.8 Gangway
4.9 Current ropes
4.9.1 Ultra violet deterioration
4.9.2 Protective measures
4.9.3 Safety of moorings
4.9.4 Table 2 - Table of mooring rope statistics
4.9.5 Diagram of moorings
4.9.6 Sketch of museum site and facilities

5.0 Conclusion

6.0 Bibliography

7.0 Acknowledgements

1.0 DISCLAIMER

The opinions stated in this paper are purely those of the author and do not necessarily reflect the views of those who administer the site on behalf of the National Trust of Australia (Victoria).

2.0 INTRODUCTION

The permanent mooring of vessels, albeit old or new, is a requirement for which they were not specifically designed. Most vessels are built primarily to carry goods between ports and to spend a minimum of time in port. Only a small percentage of the ship's working life was meant to be spent moored. As such, naval architects created basic, cheap, all purpose mooring systems. This would be as true today as it was in the 1800's. The mooring of historic vessels must therefore make use of, and adapt to, the facilities presented. This paper is prepared in order to give an overview of the mooring system, associated problems and practices used to secure the barque Polly Woodside in Duke's and Orr's dry-dock at the Melbourne Maritime Museum.

3.0 DUKE'S & ORR'S DRY-DOCK

The wet dock in which the ship floats is the last of the Yarra River graving docks to survive. Originally the site of ship construction from the late 1830's., the first dock was excavated in 1867-68. The current dock is unique in that it is constructed of Australian hardwood timbers, mainly red and blue gum. The floor was also originally of timber but replaced by concrete in 1935 to cope with the increasing weight of ships to be supported. The original dimensions of the dock were length: 527 ft (161m), breadth: 71 ft (22m), depth at sill at low water 20 ft (6.1m) .

The dock was closed using free floating, mitre gates weighing approximately 200 tons each, which were also constructed of timber, mainly Australian iron bark, the main timbers of which are 24 inch (610mm) square. The gates remain today, in the open position, recessed at the end of the dock. No longer capable of being used due to degradation of the above water timbers and silting of the gates into the river bed. A fund raising project in 1989 to repair the gates and make them serviceable was unsuccessful.

The dock was last in commercial use in 1975 when the Silver Harrier, 4,622 tons was docked. In 1977 the dock was leased to the National Trust of Australia as a permanent home for the Polly Woodside. Approximately 11,000 tons of bricks were used as fill for reducing the volume of water in the dock and as a means of stabilising the wooden walls. This also shortened the length of the dock to about 350 ft (107m). A new timber jetty was built half way along the dock at this time, to provide a secure landing area. In 1996 with the building of the new Exhibition Centre, the dock was again shortened with the construction of a concrete wall at the inner end of the dock. The length is now 310 feet (95m). The boilers and self priming, steam pumps are also still in existence. They were designed to pump 60,000 gallons (273megalitres) per minute and empty the dock ( 3 million gallons/14000 megalitres) in about one hour.

3.1 LOCATION

The museum is located on Crown Land in the heart of the central business district of Melbourne, approximately 2 miles/3.4 km from the G.P.O., acknowledged as the centre of Melbourne. It is overshadowed on one side by the new Exhibition Centre opened in 1996. Of 'modern age' architecture the building measures 3,280 ft by 98 ft, 321,000 sq.ft (1,000 m. x 30m., 30,000 sq. m.). The roof is shaped in aerofoil section which has a significant effect on local wind speeds. Upstream is situated a new 1,000 room hotel/casino complex nearing completion and across the river the World Trade Centre an hotel/entertainment centre.

3.2 RIVER CONDITIONS

The dock area is in the tidal flood plain of the Yarra River which runs into Port Phillip, a sunken river valley that was flooded at the end of the Ice Age, an area of 728 square miles (1172 sq.km) of water. The rock in the area is olvine basalt or old volcanic rock. The last volcanic activity was about sixteen million years ago. The Yarra River delta in which the museum site is situated is composed of chalk and gravel sediments brought down by the river. The length of the river is 150 miles (241 km) and flows at about 1-2 knots, although after heavy rainfall in the foothills, the current can reach 4 knots. However, as the dock lies at an orientation of 210 degrees towards the direction of flow and the ship is located 120 feet (37m) within the dock, it can be said that the current exerts no direct force on the ship and subsequently on the moorings.

3.3 TIDES

The tidal variation in the Port of Melbourne is not great. The average tide varies between -16.7 inches (-0.5m) at mean low water to +14.8 inches (+0.38m) at mean high water, a range of 2.62 feet (0.8m). The lowest tides on record are a low of -33.6 inches (-0.86m) on 19/Sep/1926 and a high of +59.8 inches (+1.52m) on 01/Dec/1934.

3.4 SILTATION

The ship floats at a draught of 8 ft. 6 ins. ( 2.6m) forward, 9 ft. (2.7m) aft. This leaves a clearance of 11 ft. (3.4m), (plus tide) to the floor of the dock. The keel blocks are in position on the floor to support the vessel should the dock be emptied. However heavy siltation of the dock has occurred over the years and there is a build up of silt on the sill and dock floor resulting in the keel blocks being covered. This has been due to the reduction of dredging of the river and changes in the method of dumping the spoil. Until recently, dredging in the river was by mechanical grab, spoil then loaded into dumb barges, which were taken out into the bay and dumped. Current practice is suction dredging of problem areas, adjacent to the river bank and quays. The spoil is returned to the centre of the river 100 feet (31m) further downstream with reliance on the rivers natural flushing properties to carry the spoil out into the bay.

Siltation was originally estimated as being deposited in the dock at the rate of 12 inches (300mm) per annum, but is now thought to be greater. A full size replica of the schooner Enterprise, 57 tons was built at the museum and launched into the approaches of the dock, just outside the sill, in July 1996. When this vessel with a maximum draft of 7 feet (2.1m) was being towed from the dock the vessel grounded on a build up of silt. This is of concern, if the Polly Woodside were to sink the silt may prevent the ship settling on to the keel blocks, in position for this purpose. Any settling on an uneven keel would result in adverse pressure on the hull and could result in the ship breaking her back.

3..5 WATER POLLUTION

Despite the construction of two removable pontoon bridges, providing public access along the wharf apron/boardwalk and a permanent floating barrier, floating detritus can always be found in the dock. The problem is worst in a westerly wind and after a heavy rainfall following a dry period when rubbish is washed from city streets and finds its way into the dock. Until recently the Metropolitan Board of Works cleaned the flotsam from the dock on a regular basis. Recent privatisation of the MMBW by the State Government has resulted in this service being stopped. An attempt to reduce river pollution has been made by the introduction of stationary, collection traps at strategic points on the river surface. By the end of March a new heavy duty boom with mesh skirt and side aprons will be in position. It is hoped that this will prevent rubbish coming under the wharves. This project is funded by the State Government.

3.6 CLIMATE

The ship is totally uncovered and exposed to the elements and it is fortunate that the climate of Melbourne is temperate and variable. The annual average temperatures are similar to Los Angeles. However, rainfall differs. Los Angeles receives 15 inches (384mm) compared with Melbourne's 25 inches (639mm). Winter temperatures are mild and frost which can seriously damage ropes by freezing water trapped between the strands, occurs only a few nights per winter. Higher summer temperatures have a drying out effect but again the use of synthetic ropes compared with natural fibre has reduced this to a minimum.

3.7 WIND

The ship is almost restored on and above deck complete with full standing and running rigging. This exposes a considerable area to windage. The construction of the Exhibition Centre, the axis of which is perpendicular to the fore and aft line of the ship has a major effect on the ship. There is a wind break effect if the wind direction is from east through south to west. However, if the wind is from east through north the Exhibition Centre has a channelling effect and increases pressure on the ship. Without any alteration of the moorings the ship now floats four feet to leeward of the position at rest. The major problem is perhaps that of sudden winds or Southerly Busters. They occur more frequently around the equinoctial periods and can produce wind speeds of 75 mph (120km/hr). For this reason there are more mooring lines on the starboard side. See table 1.

3.8 TABLE 1

Air Temp Wind Speed Rainfall
Mean Max Mean Min Average Gusts 
C(F) C (F) K/hr - (mph) mm inches
Jan 25.9 (78) 15.1 (59) 11.0 (7.0) 106 (66) 47.1 1.9
Feb 26.0 (78) 15.5 (60) 10.5 (6.5) 119 (74) 45.8 1.8
Mar 24.1 (75) 14.1 (57) 9.5 (6.0) 106 (66) 43.5 1.7
Apr  20.6 (69) 11.8 (53) 9.4 (5.9) 108 (67) 52.7 2.1
May 17.1 (63) 9.5 (49) 10.0 (6.2) 116 (72) 67.8 2.7
Jun 14.3 (58) 7.2 (45) 10.2 (6.3) 103 (64) 42.5 1.7
Jul 13.7 (57) 6.5 (44) 11.5 (7.1) 109 (68) 48.8 1.9
Aug 15.1 (59) 7.4 (45) 11.7 (7.3) 108 (67) 57.4 2.1
Sep 17.2 (63) 8.7 (48) 11.7 (7.3) 120 (75) 53.0 2.1
Oct  19.7 (68) 10.3 (51) 11.6 (7.2) 111 (69) 65.2 2.6
Nov  21.8 (71) 12.0 (54) 11.7 (7.3) 114 (71) 56.9 2.2
Dec 24.1 (75) 13.7 (57) 11.6 (7.2) 104 (65) 58.1 2.3

4.0 BARQUE Polly Woodside

Polly Woodside was launched in Belfast, Northern Ireland on 7th. November 1885 from the yard of Workman - Clark & Co., for Mr. William J. Woodside, a prominent Belfast shipowner. She was named after his wife Mrs. Marian (Polly) Woodside. The ship was designed as a general cargo carrier for the South American trades. During her working life she rounded Cape Horn sixteen times.

 

4.1 CHRONOLOGICAL HISTORY

1885 Launched Belfast Northern Ireland, registered at that port for 23 years
1885-1903  United Kingdom - South America voyages
1904 Sold to A.H. Turnbull, New Zealand, registered at the port of Lyttleton
1905-1922 New Zealand-Australia-West Coast of U.S.A. voyages 
1922 Listed as coal hulk in Sydney for Adelaide Steamship Co. registered at that port. 
1925 Coal hulk in and registered at the Port of Melbourne.
1943 Requisitioned by Royal Australian Navy, towed to New Guinea as coal hulk
1946 Towed back to Melbourne returning to use as coal hulk
1953 Sold to Howard Smith as coal hulk
1960's Laid up on the Maribyrnong River
1968 Sold to National Trust.
1972 Rebuilding commenced
1974 Last dry-dock in floating dock and painting of underwater hull
1978 Moved into present site, Duke's & Orr's dry-dock
1988 Awarded World Preservation Trust Medal for authenticity and excellence of restoration of rigging

4.2 PRINCIPAL DIMENSIONS

feet metres
Length on deck 183.5  55.9
Register length  192.2 58.6
Breadth  30.2 9.2
Depth (moulded) 17.3 5.3
Forecastle length  20.0 6.2
Quarter-deck length 38.0 1.6
Bowsprit 38.7 11.8 (inc. retractable jib boom)
Fore & main masts(lower) 63.5 19.5
Mizzen mast (lower) 65 19.8
Height of foremast 124 37.8
Height of mainmast 126 38.4
Height of mizzen 108 32.9
Fore & main yards length 61 18.6
Sail area 12,000 sq.ft. 339.8 sq. metres
Tonnage gross 678.17 tons 1919.22 cubic metres
Tonnage registered 647.67 tons
Deadweight capacity 1,000 tons

4.3 LLOYDS REGISTER DETAILS

From Lloyds Register Certificates of 1885 & 1893

 
Official Number 90129
Flag hoist K.D.C.N.
Number of decks One with break and raised quarter-deck.
Masts: 3, lower - steel, topmasts, topgallants & royals - wood.
Yards Lower steel, upper wood.
Rigged Barque.
Standing/running rigging Wire and hemp.
Stern Round
Build Clincher (raised & sunken strakes)
Figurehead Demi-female

4.4 PLATE THICKNESS

Original construction was completed under the supervision of Lloyds and the ship was classed as 100A1 on completion. Built of wrought iron and riveted throughout on frames 22 inches (0.56m) apart. The iron plates used in the construction of the hull, exceeded the required thickness. Shell plating thickness are:
As built Last Survey
inch millimetres inch millimetres 
garboard strakes  9/16 14.29
shell plating 7-8/16 11.1 - 12.7 0.5 12.5 
sheer strakes 11/16  17.5 (average)
The most pressing problem is holes in the rudder, above the waterline. Discussions are underway on how to lift the rudder and place it ashore for inspection and restoration.

4.5 BALLAST

In the lower hold, 275 tons of concrete core samples are used as ballast. This is in the form of concrete cylinders 1.5ft. x 6 inches diameter, (460 x 152 mm), weighing approximately 30 pounds (14kg.) each or 75 to the ton of (2240 Lbs). A project currently underway is raising the ballast on galvanised iron platforms built above the frames. This will expose the hull plating and provide quick access to locate and counter leaks which may occur in the future.

4.6 MAXIMUM STRESS

Four hundred was the greatest number of persons on board at one time. The occasion was a business reception. Weight was estimated at 26 tons. No abnormal stability was observed as the vessel floats quite freely and moorings have sufficient slack to prevent undue tightness.

4.7 SHIPS EQUIPMENT

To the best of our knowledge, all the ship's bitts and fairleads are original fittings. Extra fairleads were cut into the bulwarks as required during the ships life as a coal hulk. These were removed and plates welded during the initial restoration. The bolts securing the bitts to the fo'c'sle deck, maindeck and quarterdeck are also original and were refitted during the period 1972-74. Manual power using the maindeck and fo'c'sle capstans were the only sources of mechanical advantage for securing the ship. The original windlass was a 'pump action' type and no suitable replacement has been found in Australia. It is expected that a fibreglass replica will be made to complete this section of restoration. The current fo'c'sle and maindeck capstans are not original, if mooring ropes need tightening this is done manually, extra purchase being gained using a chain block.

4.8 GANGWAY

The gangway now in use is 39 ft (11.8m) x 3.9ft (1.2m) wide with safety rail 3ft (0.91m) and weighs approximately three tons. The ship end is hooked over the bulwarks 4.9ft (1.49m) high. The shore end rests on a rectangular plate rolling on four nylon covered wheels to reduce friction. To protect the wooden decking of the jetty the gangway moves over a protective plate of 1/4 inch steel, 8 feet square. Access for wheel chairs is limited to lighter models as the chairs have to be lifted on and off the gangway at both ship and shore ends.

4.9 CURRENT MOORING ROPES

The current ropes in use are made of nylon, polypropylene and polyethylene and are approximately eighteen years old. They were donated by a local rope wholesaler. See table 2. The current replacement costs for the ropes are estimated as A$ 4,000 ( US$3,200).

The moorings are arranged for a no labour situation. The ship, floating freely requires no-one in attendance to adjust the mooring lines for variations in tide or wind.

4.9.1. ULTRA VIOLET DETERIORATION

The polypropylene and polyethylene ropes are now starting to show signs of deterioration with outer layers flaking off. The nylon on the other hand shows no signs of undue deterioration. This is perhaps due to the hardening agent used during the manufacture of the nylon. These ropes are very hard and extremely difficult to splice.

4.9.2. PROTECTIVE MEASURES

To preserve the mooring lines and prolong their effective life, they are:

'End for ended' every two years
Tension adjusted monthly
Canvas parcelling tied around ropes where they are in contact with the fairleads
Onboard ends made fast on bitts and loose ends secured to keep above scuppers and decks

4.9.3 SAFETY OF MOORINGS

The head lines and forward breastlines are secured outside the steel fence which marks the boundary of the museum. This area is open to public access. Concern was felt that synthetic mooring lines could easily be vandalised either by a sharp knife or by the setting of a fire. To this end chain spacers 15 ft. (5m) long are secured to the shore concrete blocks and bollards. With the weight of chain and mooring line secured aboard, it is not possible to lift the bight of chain off the securing bitts and cast the ship adrift. The drawback to this system is that the weight of chain drags the eye of the mooring line under water at high tide causing build up of algae and rotting at the eye.

Prior to construction of the Exhibition Centre the head lines were secured to two, three ton anchors, one fluke of which was buried in the ground. The effect was both secure and aesthetically pleasing. However this system was not considered safe enough when full time, unsupervised, public access became possible outwith the museum boundaries. As a result, the anchors were replaced by concrete blocks of 35.3 cubic feet (1 cubic metre) dug into the ground 10ft (3.2m) from the edge of the dock. The weight of concrete and the static resistance of the soil are responsible for securing the ship to shore. The head line chains are secured to the concrete blocks using steel eyes set in the concrete giving minimum above ground protusion. For the springs and breast lines, port side, the lines are secured to bitts set into the concrete blocks. Sets of bitts of many shapes and sizes have been acquired over the years. Three sets of similar shape and size were selected for use. The effect adds to the nautical ambience and alleviates, slightly the storage problem of relics. The eyes of the starboard breast lines are secured over wooden bollards which were part of the original construction of the shore apron and dock. Stern lines on both sides are secured to concrete bases which were the original positions of capstans by which the ships were warped into and out of the dry-dock.

One major concern about the land based mooring points is the integrity of the above water timber which makes up the dock walls. The original timber, vertical dock sides were tied into the bank using horizontal steel piles driven into the surrounding ground. Australian hardwood timber will maintain strength and integrity below water for considerable time, however above water is subject to the vagaries of weather, drying out and pollution. Several sections of the walls have broken, fortunately not in close proximity to the mooring strongpoints. No concern is held for the head lines as they are secured on top of massive piles.

Another concern is the integrity of the soil which surrounds the mooring points. The strong points have not been tied back to solid ground. The soil surrounding the mooring points is only infill on top of the original river bank. The planting of dozens of plane and gum trees for landscaping purposes, may have the side effect of stabilising the riverbank area in the short term. However in the long term the problem of tree roots may exacerbate the dock wall condition.

4.9.4 TABLE 2

MOORING ROPE STATISTICS

STARBOARD SIDE  
Position Diameter Length * Type # Lay ** Secured on board Shore connection Shore securing
inch (mm) feet (m)
Head Line 1.9 (48)  108 (33) PE conv focsle bitts chain concrete block
Breast 1.6 (41) 50 (15) PP sqr fwd maindeck bitts chain concrete block
Fwd spring 1.7 (43) 80 (24) PE conv fwd maindeck bitts eye wooden bollard
Breast 1.6 (41)  62 (19) nylon sqr aft maindeck bitts eye wooden bollard
Breast 1.4 (36) 62 (19) nylon conv aft maindeck bitts eye wooden Bollard
Breast  1.4 (36)  62 (19) nylon conv aft maindeck bitts eye wooden bollard 
Aft spring 1.4 (36)  80 (24) nylon conv quarter deck bitts eye wooden bollard
Quarter  1.4 (36)  76 (23) nylon conv quarter deck bitts chain anchor
stern line 1.4 (36) 100 (31) nylon conv quarter deck bitts chain concrete block
stern line  1.4 (36)  100 (31) nylon conv quarter deck bitts chain concrete block
PORT SIDE
Position Diameter Length * Type # Lay ** Secured on board Shore connection Shore securing
Head line 2.1 (53) 108 (33) PE conv focsle bitts chain concrete block
Breast 2.7 (69)  40 (12) PE conv fwd maindeck bitts chain concrete block
Fwd spring 1.9 (48) 55 (17)  PP sqr fwd maindeck bitts chain bitts on concrete block
Aft spring 1.9 (48) 75 (23) PP sqr aft maindeck bitts  chain bitts on concrete block
breast  2.2 (56) 85 (26)  PP  sqr aft maindeck bitts eye bitts on concrete block
quarter  1.5 (38)  75 (23)  nylon conv quarter deck bitts chain concrete block
stern line 1.5 (38) 100 (31) nylon conv quarter deck bitts chain concrete block
SPARE
Position Diameter Length * Type # Lay **
1.9 (48)  100 (31) PP sqr
1.8 (48) 80 (24) PP sqr

Notes - * does not include chain spacer
# denotes polypropylene or polyethylene
** conventional or square

4.9.5 Diagram of moorings

Click here to see a diagram of moorings.

4.9.6 Sketch of museum site and facilities

Click here to see a Sketch of museum site and facilities.

5.0 CONCLUSION

The current mooring lines have been in constant use for the last eighteen years and maintenance costs have been minimal. No untoward incidents have occurred to the ship as a result of rope failure. This is a tribute to the shipwrights who constructed the original fairleads and bitts on the ship and also to the rope manufacturer. But more importantly it is those who have practised and continue to practise traditional seamanship skills, thus ensuring the safe mooring of the Polly Woodside, Hopefully this will continue to be the situation well into the future.

6.0 BIBLIOGRAPHY

Barque Polly Woodside (RONA), Vin Darroch, Kilmore, 1978.

Duke's & Orr's Dry Dock, A. Woodley & B. Botterill, Collingwood 1985.

Australian Weather Book, K. Colls & R. Whitaker, Brookvale 1990.

Climate of Melbourne, Bureau of Meteorology, Melbourne 1996

7.0 ACKNOWLEDGEMENTS

In preparation of the foregoing, the assistance of the following is appreciated:

Ms. A. Gibson, Assistant Manager Polly Woodside Maritime Museum
Mr. P. Kelly, Volunteer, Polly Woodside
Mr. T. Lindquist, OAM, former Chief Rigger, Polly Woodside
Capt. R. McDonell, Volunteer, Polly Woodside
Mr. S. Nunn, Rigger, Polly Woodside
Mr. G. Stuart, Volunteer, Polly Woodside
Mr. J. Yuncken, Ship's Husband, Founding chairman of thePolly Woodside Volunteers Association

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