Author Topic: Pennant Winches - What are they used for?  (Read 1661 times)

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des

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Pennant Winches - What are they used for?
« on: June 16, 2016, 21:46:53 »
I've been perusing spec sheets for a number of relatively modern AHTS and larger ocean-going tugs, and often see reference to "Pennant winches".  I see from photos that they are often located on an upper deck, but the locations I've seen suggest that these winches can be used as tuggers (for instance, to haul an anchor aboard on the aft deck), or, as the name suggests, to haul pennants (flags to lubbers) and shapes to a yard-arm.  The spec sheets often show a rating of 3 - 5 ton capacity, which seems too much just to raise a bit of cloth to a yard, but too small to haul anchors aboard.  None of the tugs or AHTS ships that I worked on had these as original equipment, but at least one vessel had them fitted later in life.

Can anyone please shed some light on this for me.

Des.

VANYA

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Re: Pennant Winches - What are they used for?
« Reply #1 on: June 17, 2016, 15:06:14 »
See end first paragraph.

Anchor Handling / Tug / Supply / Service Vessel
An Anchor-Handling Tug [AHT] moves anchors and tows drilling vessels, lighters and similar vessels. An Anchor-handling Tug/Supply [AHTS] is a combined supply and anchor-handling ship. An Anchor is a heavy hooked instrument which, when lowered to the seabed, holds a vessel in place by its connecting cable. An Anchor Handling Tug is a tug equipped with a winch to lift a working barge's anchors. It is also often used as the working barge's tow tug. An Anchor Pendant is a wire which is attached to the crown of an anchor, enabling it to be pulled out of the seabed. The pendant wire is used by the anchor handling tug to set and retrieve anchors using the cable eye on the free end of the wire.

An AHTS is an offshore supply vessel specially designed to provide anchorhandling services and to tow offshore platforms, barges and production modules/vessels. The vessels is also often used as standbye rescue vessles for oilfields in production. The AHTS is then often equipped for fire fighting, rescue operations and oil recovery. The AHTS is also used in general supply service for all kinds of platforms, transporting both wet and dry cargo in addition to deck cargo. The focus has been on the vessels' winch and engine capasities as oil activity has moved into deeper and deeper water in order to offer the oil companies a safe and efficient operation in the challenging conditions of the deepwater area.

The Oilfield Publications Limited (OPL), Anchor Handling Tugs and Supply Vessels of the World (AHTS) Database, is a Microsoft ACCESS database of Offshore Supply Vessels and anchor handling tugs. This database includes basic vessel characteristics and owner information. It is one of the only complete sources for OSV and AHT vessels. There is no other online register which gives you all the facts on the world's fleet of anchor handling tugs and supply vessels and this new eleventh edition is the best ever. In it you will find essential specification, performance and capacity data for over 3550 ships, providing offshore service and support worldwide and much more, Incuding: General data on ownership, flag, classification, year built and builder, previous names, modifications and upgrades; Dimensions including deck areas; Machinery with details of main propulsion, propellers, thrusters and joystick control and DP if applicable; Capacities for bulk/liquid mud, cement, deck cargo, potable water, fuel etc; Towing equipment with details of winches, stern rollers and bollard pull; and a Directory of owners and managers. Anchor Handling Tugs and Supply Vessels of the World is also available as a book, a cd-rom and a wallchart.

Anchor handling vessels are designed with high horsepower to tow drilling units and perform anchor handling operations as well as the ability to carry supplies to platforms. The increase in deep water exploration has led to higher horsepower vessels to handle the heavier gear required to operate at such depths. In the offshore service vessel fleet, new deep-draft, very large, high-horsepower anchor handling/tug /supply vessels have evolved to move these large new sophisticated drilling rigs, handle their anchors, chain and mooring lines, and meet all kinds of service demands of the new generation of deepwater rigs and production platforms. It is possible that the industry might move in the direction it did back in the late 1970s and build some ships which are intended to do less than the whole job. In those days the specialist ships were AHTs, and they were found to be more efficient than ships with longer decks which were trying to do the supply job as well.
VANYA

des

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Re: Pennant Winches - What are they used for?
« Reply #2 on: June 17, 2016, 15:43:19 »
Thanks Vanya.  I guess the older AHTS's would simply have used one drum of their main towing winch to raise the anchors off the seabed and drag it on board.  But I can see that using a 2 or 3  inch wire for that would involve a lot more effort, than if using a lighter wire on a lighter winch.

Des.

Volker

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Re: Pennant Winches - What are they used for?
« Reply #3 on: June 18, 2016, 06:56:21 »
Here is what I found out reading a number of online-sources and books:
AHTs and AHTS still have to use their anchor handling/ Towing winch to lay or retrieve anchors. The forces involved are much too high for pennant winches/ pennant reels with approx. 15 tonnes pulling power. At 500 m (1640 ft) water depth anchor, anchor chain, and anchor wire weigh up to 400 tons.

Here is a link how to retrieve an anchor: http://www.menkent.dk/anchorhandling.html

As you can see everything is done with tugger and towing winch. The pennant winch on AHT and AHTS are storage reels for pennant wires. These are needed in case anchor buoys are used.

Here is the link to the anchor handling manual of the Norwegian Marine Safety Forum: http://www.marinesafetyforum.org/images/Anchor-Handling_Manual_Template.pdf

I'd be glad if someone corrected me where I'm wrong.
Regards, Volker