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 (firstname.lastname@example.org) 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.
|Crane & Platform||24,000 lbs.|
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 for the system are as follows (60 Hertz):
|Control Van #1||480V 3ø||100A|
|Control Van #2||480V 3ø||60A|
|Rigging Van||110V 1ø||20A|
|Survey Winch||480V 3ø||700A start (200 max. running)|
|Knuckleboom Power Pack||440V 3ø||55A|
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.