Thread: Interesting Old Equipment, Projects & Work Places

Oil Rig Tenders

The offshore oil industry has always been a cycle of boom and bust. At this particular time, it was booming! Having just returned from being away for a couple of months with the delivery voyage from Japan, and AOS agitating for me to start, I asked if my then wife could accompany me to Newcastle. No problem, just had to pay for her air ticket, accommodation would be covered by AOS.

My memory dims about the name of the hotel, but maybe it was Noah's on the Beach? What I do recall is that the road along the beach was a parking spot for perverts that used binoculars to try and look into the rooms over looking the ocean as the morning sun shone on the hotel!
I was allocated a hire car which included fuel, just drive into the depot and fill it up! There was no restriction on its use and several Sundays were spent exploring the Hunter Valley vineyards!

If I recall correctly it was the "Lady Vera" that was still on the slipway under construction, as somewhere I have a photo of her launching. All of the ships built at the Tomago yard were sideways launched, a most spectacular event! The construction was well advanced before launching, the engines already installed but not yet commissioned. It was here that I first came across "Chockfast". The final alignment of the engines, gearbox and shafting was done after launching with the vessel afloat.

Chockfast Orange

The first two ships built in this series, Lady Lorna and Lady Laurie, were smaller than the following ships. They were fitted with two English Electric V8 diesel engines as used in locomotives, if my memory serves me correctly. I did sail on one of them at one time as second engineer, but only briefly.

All the following vessels in this series were fitted with 4 x 1,100 hp Daihatsu 4SCSA 8 cylinder inline diesel engines. They were arranged in two pairs driving a reversable output gearbox into a conventual prop shaft, port and starboard. I cannot recall, but I think that the fixed pitch props were ducted, Kort Nozzle style. It was very easy to clutch each engine in or out of the gearbox with a simple lever, giving the option of running on either 2 or 4 engines on each side. On simple supply run trips, it was usual to run on just 2 engines, thereby saving fuel. For anchor handling or towing all 4 engines were used.

A complete bulk cement handling system was installed. Vertical silos were built into the forward cargo space, to carry both cement or barites. A big electrically driven air compressor running at around 3 or 4 Bar I think, provided the force to shift the bulk material. There was a remote control panel inside the upper deck level, inside the small workshop in fact, where pressures and valves could be controlled. I think that the flowlines were around 4 inch - 100mm. A rubber "shipping hose" was used to connect to the rig. Constant attention had to be exercised while using this system to prevent blockages and spills. It was not unknown for some roughneck on the rig to close the wrong valve while supplying cement!

Diesel fuel and "drilling water" also had to be shipped to the rig. One of the problems around this time was that different rig crews used different units. The American crews were the worst, and were completely bluffed by any mention of litres. I recall one time being asked how many "litres" of cement we could give them. Fuel figures had to be converted for them along with water.

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Oil Rig Tenders

Electrical system: Memory dims, but for sure there were two AC generators in the main engine room. Despite much searching I cannot recall exactly what kVA these units were, although I am sure that the engines were V8 diesel Caterpillars. The bow thruster was the biggest single load at around 250 kW's, so the generators were probably 500 or 600 kVA.

The MSB and MCC's were built into the forward bulkhead of a small air conditioned control room. There were two separate bus bars, but I cannot recall if there was a bus tie breaker, I don’t think so. There was defiantly no synchronization of the two generators. Manual rotary selector switches enabled each sub feeder to be switched to either bus bar depending on the load. In addition, there was a "deck set" generator big enough to run the hotel services, fire pump and such like while at anchor or in port. This was a great idea, as while doing any engine room maintenance there was no noise in the engine room! Obviously, there would have been some form of interlock on the feed from this generator.

The air conditioning plant was mounted in the same space as the bulk cement silos. I am sure that there were two units, each one of sufficient capacity to handle the load alone. What I cannot recall is the condenser cooling. Most ships use sea water cooled condenser's, but I am inclined to believe that these were air cooled. The same with the refrigeration units, I just cannot recall. Whatever they were they must have been reliable, or otherwise I would recall having problems with them! There was both a cool room and a freezer room installed below the accommodation block, in the same space as the bow thruster motor. (more about this motor later)

The engine room had the usual assortment of water pumps, cooling fans and lighting. There was a fairly basic engine alarm system. I think that the engine starting was by direct air injection, but may have been air starter motors, in whichever case there was at least one air compressor and tank. The steering motors were electric motors driving swashplate variable output hydraulic pumps.

The navigation equipment was up to date for the time. HF and VHF radios, radar, autopilot and direct engine control from the bridge. There were two control stations, one in the normal position looking forward, and the other at the aft end of the wheelhouse overlooking the working deck. There was of course no GPS in those days. Some of the later builds had Loran-C or Decca Navigators, I am not sure which, but as these ships were used in coastal areas long range navigation was not really necessary.

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Oil Rig Tenders

These vessels are referred to as A.H.T.S., that is; "anchor handling tug supply".
They are built primarily to handle and set the anchors of moored type floating oil drilling exploration rigs. These rigs could be either drillships, or semi-submersible rigs. The rigs anchors used around this time were usually of the Danforth type, but there are several different types in use. BIG anchor chain is used to connect the anchor to the rig, or sometimes wire cable, or a combination of both.

A big "float" is needed and additional wire ropes called "pendants" are used to attach it to the anchor after it is set. All of this equipment belongs to the rig, not the tug.
(in some areas, the Bass Straight being one of them, seals will take over a float and claim it is his home. When it comes time to retrieve the float they will holler and swear at anybody trying to dislodge them!)

The most important and heart of an AHTS vessel is a BIG anchor handling and towing winch!
These winches are usually of the "waterfall "type, where there is one BIG drum that carries a long towing line (belongs to the tug), and one or two smaller drums that are used to store and handle the "pendant" wires.

waterfall winch.jpg

In this case the winches were built in Australia, I believe in Adelaide, but I am not sure.
A trusty Caterpillar 6 cylinder diesel drove an Alison industrial gearbox, inputting to a reduction gearbox. Not sure if the drives to each drum were gear or chain, but as I never saw one that broke, probably gears. Unfortunately, the same cannot be said of the Alison transmission. They used to regularly chew up clutch packs, usually at the most inconvenient time! We had a regular mechanic from an Alison agent that could repair them in just a few hours once he was on board.

The winches were controlled from a reinforced "cage" overlooking the ships working deck by one of the ships engineers. Although I did not have to personally repair them it bugged me for a long time as to why the Alison transmission used to fail. Several years later while working on a rig with electric anchor winches it hit home. With the electric winches we used to clutch out the motor while running an anchor to avoid over speeding the motor. The brake drums were water cooled and the speed was controlled by juggling the brake. The same SHOULD have been done with the Alison transmission, as I now believe it was both over speed and possibly reversed thrust that was chewing up the clutches.

Working on the deck whilst handling anchors has to be one of the most dangerous jobs anywhere. Even in good weather conditions the working deck is usually awash, as it is close to the waterline. All of the equipment is big and heavy and a lot of the time under tension or being moved around. Small air tugger winches and snatch blocks are used to position equipment.

The pendant lines are usually passed from the rig first if there is none already on the tug. The lines are around 50 ft. long x 2 inch wire, but do vary. Each end is fitted with a spelter socket. They have to be made up with big shackles to suit the water depth and wound on to one of the smaller winch drums ready to be used.

Next the anchor is passed from the rig and laid on the deck. The anchor is already connected to either the big anchor chain, or wire cable, on the rig. Chain is the most common as its weight is what mostly holds the rig in position. There are several different anchor patterns used, but all of the rigs that I ever worked on had eight anchors.

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Oil Rig Tenders

The rig anchor has to be "run" by the tender to a predetermined position and placed on the seabed. The rig heading is determined by the prevailing weather conditions, usually head up into wind and waves. The actual position of where the well is to be drilled is also predetermined by seismic surveys and usually marked with a small anchored floating marker.
I guess that these days it is done using GPS.

The most common "anchor pattern" for a floating rig is usually comprised of four "breast anchors", that is to say two anchors perpendicular to the rig centreline, one each forward and aft of the rig on each side. The other four anchors will be at around 45 degrees either side of the rig centerline, two forward and two aft.

Spread Mooring Systems - Offshore Drilling - Netwas Group Oil

Semisubmersibles - an overview | ScienceDirect Topics

The water depth will determine how long the anchor cable is, up to 10 times the water depth in some cases. The weight and type of anchor also varies, but probably between 10 and 15 tons deadweight.

cantenary.jpg

This will also vary depending on the type of rig, drillship or semi-submersible. On a drillship the mooring winches and fairleads are at main deck level. The anchors are stowed on the rig on "cowcatchers" protruding out from the hull.

The first problem is connecting an initial line on to the anchor so that it can be landed on the deck of the tender. If the rig crane cannot reach the anchor or chain then usually some form of "chaser" has to be used that is wrapped around the chain or wire and then a connecting line is passed to the tender. Sometimes the rig anchor will already have one length of pendant wire left on it from the last job, so the end of it can be pulled on to the tender with a messenger line. Whatever is used the object is to land the anchor on the deck of the tender

There are two different methods used to "carry" the anchor while running it out. The most common is to use the mentioned pendant wires. One end is attached to a pad eye on the head of the anchor and then sufficient lengths of pendant line are joined together to suit the water depth and wound on to one of the waterfall winch work drums. Using this method, the anchor is held clear of the seabed as the tender pulls it out in the required direction and length, where it is lowered on to the seabed. The previously mentioned big float is then attached to the last section of pendant wire.

The other method, which I have never seen used, is just to use a "chaser" without using any pendants and float. Installing and then removing a chaser strong enough to carry the load is a problem. Sometimes, if the float were to break away from a pendant, then it is necessary to use a chaser to retrieve the anchor, so such an item may be on board.

To help facilitate moving the weights and tensions involved, the aft end of the tender has a big built in roller at the stern nearly the complete width of the hull. Sometimes a tender may also have some form of "A frame" at the stern, but AOS only ever had one vessel fitted with this in my time and it was a PITA!

The other piece of complete "widow maker" tool was what we called a "pelican hook".
I think that the Yanks call it "alligator or crocodile jaws". Both when running or retrieving the anchor it is necessary to have some means of holding one section of pendant line while inserting or removing the next section. Under load this monster had to be released by hand standing next to it with a BIG hammer!

Pelican Hook | SWL3.5T To SWL150T, Marine & Shipping Industry | Pilotfits

Regardless of rig type the tender has to be able to both handle the weight involved, plus have sufficient propulsion power to pull the combined weight of anchor and chain the required distance from the rig, in an accurate direction.

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Oil Rig Tenders

The ongoing operation of running all of the rig's anchors can take a couple of days or more, depending on weather conditions and other variables. In my time the tender crew consisted of just eight people. Two deck officers, captain and mate, two engineers, chief and second, and four AB seamen, one of which acted as cook!

The physical work on deck is both dangerous and very tiring, which can and does lead to accidents and injury. The tender captain of course had the authority to stand down for a break if he considered it necessary. On some occasions, or if on a long rig move, then extra crew would be put on board. The usual watch standing was 6 hours on followed by 6 hours off, but that went out the window when running anchors.

For the engineers all available power would be online, four engines, bow thruster, both steering motors, the waterfall winch would be running and most other auxiliary systems.
At this time the engine room alarm system was very basic and not classed for unmanned operation. (more about this later). Combined with operating the waterfall winch he had to continuously check the engine room, maintain sufficient fuel, move ballast water around if required and generally be in three places at the same time!

For the captain of the tender the stability of the tug had to be continuously foremost in his mind. He needed to be very experienced and have situational awareness at all times. Once he commenced actually running the anchor the weight and drag was continuously increasing, so it was imperative that he maintained the planned heading and not allow the towline to move off the centreline of the vessel.

Once all of the anchors have been laid in position they are allowed to "soak" for 24 hours or so before the rig starts to "tension up" on them. If they all hold ok the tender is then released back to "stand-by", or if there is a problem with an anchor dragging then it may have to be picked up and re-laid. In later years while working on rigs I was involved in this operation from the rig side.

To close this part the first year that I was stand-by at Carrington Slipways the "Lady Vera" was launched and commissioned. Some old hands may well remember the grounding and wreck of the Norwegian bulk carrier "Sygna", which went aground on Stockton Beach.

Sygna: All hell broke loose, then so did the ship | Newcastle Herald | Newcastle, NSW

I recall being in discussions concerning the salvage rights using Lady Vera, but I had departed the area before the job actually started, so I did not see any of the extra money paid to the crews!

As a stop-gap solution he hired the sea-going supply ship Lady Vera for three times its normal charter rate and paid bonus wages to a crew that amounted to twice its normal complement.

685592.jpg

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Oil Rig Tenders

I never did know just what my "official "position was with AOS, but "general "dogs body" was not far off the mark! After my first stint at Carrington Slipways I served on several tenders as second engineer. I recall going to Singapore with the then superintendent engineer early on in my time, probably to attend a dry docking of a vessel.

I was employed on an equal time on and off basis, as was the then accepted standard: 5 weeks on followed by 5 weeks off, but it did not always work out that way. I lived in Albany on the south coast of WA at the time, so wherever I went involved 2 or 3 flights. AOS had several tenders working on the WA north west coast at that time, mostly out of Broome and Darwin. They were continuing construction of more tenders and I did go back to Carrington Slipway the second year that I was employed to stand by the next vessel.

I think that I will add a few photos at this point to show some of the tenders and also the oil drilling rigs. Several rigs were either built or converted in Australia around that time. Maybe this comment would be just as relevant in the thread about Australian manufacturing.

Ocean Digger:
First generation semi-submersible oil rig. The 9100-ton OCEAN DIGGER built for Ocean Drilling and Exploration Co. (ODECO) Australia Ltd by BHP Shipbuilding & Engineering Works, Whyalla, Australia. Completed 16 September 1967. 300 ft. wide, 365 ft. long and 204 ft. high. It could operate in water up to 600 ft. deep and drill to 20,000 ft. It had accommodation for 35(?) men. Used by the Burmah Oil Company (taken over by Woodside Petroleum)

OCEAN_DIGGER.jpg

This oil rig was where a lot of Australian "rig pigs" crew cut their teeth. I never worked on it, but did transit a few times to or from a tender. It had a "meccano" slewing deck crane; I think it was called a "stiff leg"? To transfer we had to ride on a Billy Pugh basket, and the whipline hook used to feel like a Land Rover on a corrugated road!

billy pugh sml.jpg

billy pugh 2.jpg

It was also a big customer of drilling material and a regular run for AOS tenders. In the time that I was there the supply base was in Broome.

Regional Endeavour: Original name "Mount Kembla", built in 1960.
10,112 gross tons, 5,302 net. 13,700 dwt. Lbd: 512'9" x 64'7" x 28'5". Ore carrier built at BHP Whyalla Shipyards, South Australia. Sistership Mount Keira. June 1973 sold to Drillships Ltd., Australia for conversion to become an offshore drilling vessel. July 1973 renamed Regional Endeavour. December 1974 modified to include relocated bridge structure further forward as well as drill tower and helipad added. January 1979 sold to Western Selcast Pty Ltd., Australia and later transferred to their mining division. 1988 renamed Endeavour. Scrapped 1988

regional endeavour.jpg

I did not work on this one either, but I do recall being asked to witness the generators load test during its commissioning in Newcastle. NSW. (1974?) I am not sure just why that happened. As far as I recall it was just a resistive load test using a brine water tank, which I assume belonged to the shipyard that built the conversion. It MAY also have involved an inductive component as oil rigs have a notoriously poor power factor.

For the tenders I do not recall doing any total load test as the relatively small load was easily calculated and the power factor not a problem.

This was the oil rig involved in the loss of the AOS tender "Lady Ann" off the coast of WA in 1982. I think that I was stand by the Lady Ann in 1975, but had left the company before this accident happened.

https://www.atsb.gov.au/media/24898/mair1_001.pdf

Lady Anne.jpg

All of the AOS tenders built in Australia at least, were named, or "sponsored", after P & O directors or upper managers wives. The "Lady Ann" sponsor was the wife of the manager of AOS in Australia, Duncan McBain.

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Oil Rig Tenders

Ocean Endeavour: In 1975, on another beach, 5,000 kilometres to the west, on Cockburn Sound, south of Perth, Transfield completed a giant new oil exploration rig. The Ocean Endeavour is a 20,000 tonne semi-submersible, self-propelled platform, the second of its kind ever built in Australia. The construction site was nothing more than a dredged beach allowing the completed rig to be towed out from a flooded basin.

Unfortunately, the project wasplagued by industrial disputation resulting in major overruns. By the time oflaunching, in September 1975, oil exploration in Australia slumped and the rigwas towed away to work off Tunisia. However the project won for Transfield thefirst of four coveted Construction Achievement Awards.
Ocean Endeavour construction basin.jpg

ocean endeavor and lady anne.jpg

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By now becoming used to being "dogsbody" I received a call to join this rig after it was completed and anchored out off of Fremantle. I think it was only for a few weeks until its future was decided, and another engineer and myself were there just as "caretakers".
It was fitted with old DC former submarine propulsion motors which we did not use in my time. It also had a mongrel fresh watermaker that absorbed most of my time!

I had been driving past the construction site for a couple of years beforehand and never dreamt that one day I would be on the thing!

Energy Searcher: I will add this one here as many years later I ended up chief engineer on it, amongst other assignments.
The ship was built as the bulk ore carrier "Lappland" and delivered in 1959.

GT 12964 | NT 5378 | dwt 18650 | grain 413145 ft³
Loa 177,70 m | Lpp 167,70 m | Beam 21,30 m | Draught 9,12 m | Depth 11,96 m
Engine: 1 x 2-stroke 6-Cyl.-B&W/Eriksberg Mekaniska Verstad AB-diesel engine – 7200 BHP – 15,5 kn
Shipbuilder: Eriksbergs Mekaniska Verkstad AB., Gothenburg – Yard No. 490 – launch date 09.06.1959 -

1982 lg and widended and converted to drilling ship
ex ENERGY SEARCHER (1981-1983) - Pacific Suppliers Inc., Panama/PAN

The conversion was done at HUD (Hong Kong United Dockyard) in 1982. The rig worked off the Australian coast for around 10 years, before being repossessed by the banks and sold overseas.

energy searcher.jpg

Also, around this period the "Penrod 76" semi-submersible rig was operating on the NW Shelf, which we also serviced. Penrod also had a rig working in NZ, either around this time or a bit later.

Just to show that the industry at that time was booming, AOS had tender working out of New Plymouth in NZ. I don’t recall how I came to be there, but I do recall getting back to Australia! I may have been there either as second engineer, OR I had been there as an extra to sail the tender to NZ. Whatever it was AOS sent a Bib Stilwell Learjet to crew change some of us back to Melbourne! What I remember vividly is barrelling up whatever street it is that aligns with a runway, (Essendon?) at rooftop level in a typical Melbourne afternoon rain storm!
The following photo may or may not be the actual aircraft. I do have a photo of it but it is stored away in Australia.

lear jet.jpg

As a point of interest, the Maui Gas Field is still in production. At the time that I was there the installation of the "Jacket" had been delayed for eight months because of the weather conditions. Bass Straight is known for high seas, but this location wins hands down for rough conditions!

Maui Platform A

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This last comment reminds me of an interesting bit of history. When BHP started exploration for oil in Bass Strait in 1963, nobody, anywhere, had ever either drilled a well, or produced oil or gas in that water depth or in open water with weather conditions that exist there. But they knew that other companies were about to do so (but not in Australia).