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Jason/Medea Support Vessel Requirements

To give the user an idea of the general support vessel requirements, the following are specifications for a Jason/Medea support vessel. These requirements are intended as guidelines for the selection of a ship suitable for offshore operations.

Use of non-UNOLS vessels should be approved by Jason manager Matt Heintz (mheintz@whoi.edu) and will require additional funding.

ISO Shipping Containers

Six 20’ x 8’ x 8’ ISO shipping containers (vans) fitted out as control rooms and workshops. Each container weighs approximately 17,000 pounds. Each container must be secured to the deck.

Deep Sea Survey Winch

This assembly is comprised of the following components:  

  Weight Size (L x W x H)
Traction Unit 22,050 lbs. 12 ft. x 7 ft. 3 in. x 12 ft.
Level Wind 2,900 lbs. 7 ft. 9 in. x 4 ft. 3 in. x 6 ft.
Storage Drum 30,800 lbs. 7 ft. 9 in. x 7 ft. 3 in. x 6 ft. 8 in.

Effer 80000 LARS crane with ROV docking head

This component is used to deploy and retrieve the ROV and thus must be placed on the deck near the overboarding point of the main tow cable. Note that the ship’s deck must be sufficiently strong to withstand the loads resulting from operation of this piece of equipment. A working area for the ROV serviced with this crane must be provided; deck space of 200 sq. ft. will be adequate.

  Weight Size
Crane & Platform 24,000 lbs.  
Power Pack    

Tow Cable

To support the subsea system, the ship must be capable of handling a tow cable over the side. This cable is an electro-optical design with steel reinforcing armor. Typical overboarding of this wire is done from a sheave mounted to either an A-frame or suitable crane. Tow point locations at the stern (on centerline) or amidships over the side have been used. A tow point must be at least 10 feet outboard and 10 feet above the deck plane. Tow points must also be capable of supporting a maximum wire load of at least 42,000 pounds. Additionally, mounting points should allow deployment and recovery of the wire from its outboard location to a point no less than 5 feet inboard. Should the candidate vessel not have sufficient overboarding capacity, an A-frame will be installed as part of the system. As with the LARS crane, the ship’s deck must have adequate strength to support this installation.

  Weight Size (L x W x H)
A-frame 10,800 lbs. 15 ft. x 12 ft. x 17 ft.
9 ft. 9 in overboard reach

Power Requirements

Power requirements for the system are as follows (60 Hertz):

 Voltage Amperage
Control Van #1 480V  3ø    100A
Control Van #2480V  3ø     60A
Rigging Van110V  1ø     20A
Survey Winch480V  3ø     700A start (200 max. running)
Knuckleboom Power Pack440V  3ø     55A

Station Keeping

To accomplish precise surveys with the ROV system it is necessary that the support vessel be capable of station keeping while at sea. Ships that have been used previously have all been equipped with dynamic positioning (DP) systems capable of receiving positioning input from external sources. These inputs are normally provided from systems such as GPS or long baseline underwater acoustic sources. These sources are part of the Jason/Medea system and have been tailored as inputs to a specific support vessel’s DP controller. Station keeping within a watch circle not exceeding 80 feet is required.