Winches & Wires

Dual Traction/Stowage Winch System

This winch is located below decks in the Winch Room under the fantail.

This is a dual-drum winch. The cable is led from the winch either through a series of fairlead sheaves mounted below decks to the ship's trawl crane, or through an alternate fairlead sheave train to the port hydro boom. Sensors for the wire monitoring system are mounted on one of the fixed sheaves. Construction of the sheave train prevents the passage of shackles and other fittings. Special rigging is required to handle long net bridles, pendants and terminations.The primary winch control is located in the control center over the submersible hangar. The operator has a clear view of the entire main deck work area and instrument landing spots at the stern and the starboard side. The operator has intercom communications with the bridge and laboratories. Winch parameters (line count, line speed and tension) are displayed at the control center, in the labs and on the bridge. An auxiliary control stand is located at the winch below decks. Provisions are made for the use of a remote control station which can be placed in the main laboratory or a portable van as required. A closed-circuit video system allows monitoring of the below-deck winch and sheaves as well as main deck activities.

One overboarding sheave is mounted on the main shipper boom of the trawl crane. The crane can be positioned either over the stern for towing operations or over the starboard side for coring and instrument recovery operations. The crane boom is raised and rotated to launch/recover instruments. When lowering instruments, the crane boom is placed in a crutch for added strength and to relieve the stress on the hydraulic system. The other overboarding sheave is located on the end of the port hydro boom, as is most often used for remotely operated vehicle (ROV) towing.

Hydro Booms

The hydro booms serve as common overboarding support structures for the hydro and traction winch cables.

The starboard boom overboarding point is located amidships in the area of least ship motion in a seaway. The unit is a McElroy hydraulically powered extendable boom with 15,000 lb capacity, mounted on the 02 Deck. Two head blocks are hung from the end of the boom. When the boom is retracted, the wire plumbs over the main deck. A bulwark gate can be opened to allow passage of instruments.

The port boom overboarding point is located near the ROV hangar. This unit was also built by McElroy and is mounted on the 02 Deck, and has a capacity of 25,000 lbs. It is designed to launch and recover ROVs and supports the wire from the dual traction winch system.

The hydro booms do not raise or rotate. Controls are located in the control center.

Oceanographic Cables

Four standard categories of oceanographic cables (trawl, hydrographic, electro-mechanical/CTD and fiber optic) are available on board WHOI vessels.

The significant characteristics of each wire are given in the following table.

Spares exist for each type of oceanographic cable. In general, where space and availability permit, spares are carried aboard. On extended multi-leg cruises backup cables are always placed aboard.

All oceanographic cables aboard WHOI vessels are lubricated during manufacture with Grignard Chemical Co. Pre-Lube #6 or #19. Cables are periodically rinsed and lubricated with the same product during service.

It is imperative that oceanographic cables be used in a responsible manner which does not compromise their availability to subsequent investigators. Cables are expensive and at times in short supply. Reasonable care must be taken to maintain their integrity and extend their useful life. Questions related to the use of cables should be directed to the Marine Operations Coordinator during cruise planning.

Notes, cautions, and restrictions to the use of cables:

1. Cables are not to be loaded in excess of their safe working load. Caution must be exercised in lowering instruments which are heavy, entrap large volumes of water, or produce excessive hydrodynamic drag forces. This is particularly true when operating in moderate sea states or water depths greater than 4,000 meters.
2. Cables will not be permitted to pass over sheaves which are not properly sized (groove size and tread diameter) for that cable.
3. In general, devices are not to be clamped onto any conducting cable. This is to prevent damage to conductors and their insulation. The exception is that devices may be clamped within 100 meters of the termination.
4. Certain operations, such as dragging for moorings, deliberately subject cables to severe abuses such as kinking and abrasion. Whenever possible, the main cables will be protected from abuse by splicing or attaching sacrificial wires of comparable strength to the end.