DSL120A - 120 kHz Deep Towed Mapping System
Support Vessel Requiremnets
The following are the general specifications for a DSL120A support vessel. These requirements are intended as guidelines for the selection of a ship suitable for offshore operations.
Non-UNOLS vessel use should be approved by DSG and will probably require additional funding.
ISO Shipping Container
One 20’ x 8’ x 8’ ISO shipping container (vans) containing all the DSL120A, depressor weight, and supplies will be sent for a cruise. Each container weighs approximately 15,000 pounds. The container must be welded (or bolted) and chained to the deck (total area required is 740 ft.2).
Deep Sea Survey Winch
This assembly is comprised of the following components:
| Weight | Size | |
| Traction Unit | 22,050 pounds | 12’L x 7’3”W x 12’H |
| Level Wind | 2,900 pounds | 7’9”L x 4’3”W x 6’H |
| Storage Drum | 30,800 pounds | 7’9”L x 7’3”W x 6’8”H |
| Diesel Power Pack | 7,500 pounds | 11’L x 4’W x 7’H |
The winch is normally mounted on the centerline near the stern of the vessel.
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 50,000 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 HIAB crane, the ship’s deck must have adequate strength to support this installation.
| Weight | Size | |
| A-frame | 10,800 pounds | 15’L x 12’W x 17’H 9’9” overboard reach |
Power Requirements
Power requirements for the system are as follows (60 Hertz):
| Voltage | Amperage | |
| Survey Winch (if diesel is not used) |
440 30 | 700 start (200 max. running) |
Note that if the survey winch is powered by its diesel, no electrical power from the ship is needed. In this case however, diesel fuel from the ship will be required. Power pack must be filled once each day the system is operated, and tank capacity is approximately 55 gallons.