Site: Slingsby Engineering Ltd. (SEL)
York Y06 6EZ
United Kingdom
Telephone: (0751) 31751
Fax: (0751) 31388
Telex: 57911

Date Visited: May 12, 1993

Report Author: C. Brancart



D. Blidberg
C. Brancart
L. Gentry
J. Mooney


J. Sampson (ONR London)


David Hartley, B.Sc.; Technical Manager
A.G. Coulter, B.Sc., Ph.D.; Deputy Technical Manager
Brian Forbes, O.B.E., M.N.I.; Consultant, Submarine, Marine, and Underwater Systems
John Digman; Slingsby Aviation Ltd., Marketing Director


Slingsby started business by being part of BUE, a holding company owned jointly by the British government and commercial entities. In 1986, ML Holdings was founded, and Slingsby Engineering became part of a multidivision corporation.

The firm is located in the Kirkbymoorside countryside near Thirsk, halfway between Manchester and Newcastle. At this location, there are two separate Slingsby companies: Slingsby Engineering, which is involved with underwater hardware and systems, and Slingsby Aviation, where the T67 Firefly, military basic training aircraft, is fabricated.

Slingsby Engineering has a staff of about 80 people. The corporate thrust is the offshore oil marketplace and telecommunications (underwater cables). Specific areas of involvement are:

Underwater systems:

Underwater equipment:

Engineering services:

Test facilities:

Slingsby has respectable test facilities, especially for pressure. It has numerous small pressure tanks, and a large test tank, 8.5 m long x 2.8 m diameter (27 ft long x 10 ft diameter), rated for 7,500 ft of sea water (3,350 psi). SEL uses water as the test medium and has numerous throughput wires for testing, but no temperature controls. The wet tank is 30 ft x 10 ft x 12 ft deep, and the mud/bottom basin is 7 m x 24 m.

Slingsby Engineering has designed and built numerous manned systems in the past, but current market demand is such that the company is only involved with unmanned systems. In 1978, Slingsby built the last of five submarine escape and rescue vehicles, the LR5 Rescue Submarine. The LR5 has a maximum operating depth of 1,500 ft and is capable of carrying nine rescuees on each trip. Number 5 boat is presently on stand-by duty for the Royal Navy. In 1986, Slingsby designed and built the JIM suits, a one-atmosphere carbon-fiber-skin diving suit rated for 1,500 ft operating depth. This market was short lived because of the trend toward unmanned systems, the ROVs. Other previous projects have been the Scarab III water jet system for cable burial, bottom crawlers with trenching capabilities, and a system to place a very large cover plate over the tension-leg cables of a surface platform. SEL also performed the Dolphin 10K study, which has ended up being the 10,000 m ROV for Japan.

Presently, Slingsby is concentrating on large working ROVs. The company started with the TROJAN series, and is now building the MRV series. Associated support equipment ranging from power packs and manipulators to handling systems are also being developed.


Slingsby's major product line consists of the large ROVs and associated support components and systems. The Trojan ROV, which is approximately 7 ft x 5 ft x 5 ft, 4,000 lbs, and rated for 3,300 ft, was the first of a series. The company's scientists and engineers built thirteen units and sold twelve. They made the mistake of showing their customers the next generation unit, the MRV ROV, and the thirteenth Trojan unit is still for sale. Typical of the Slingsby philosophy, the system is modularized with optional power packs, variable ballast option, and seven function master/slave to five function manipulators, or both. Each vehicle comes with a topside control van, rated for offshore platform use, handling systems, both the surface winch and A-frame, and the underwater garage. Additional options are available based on customers' needs.

The multirole vehicle (MRV) is designed to be flexible. There are many possible variations available (see Table Sling.1).

Table Sling.1
Design Variations of the MRV

The options are as varied as the customers' needs. Vehicle options include power, tools, cameras, lights, and navigation equipment. Systems options are umbilical (soft or armored), topside handling systems, control cabin and consoles, tether management system (TMS), and specialty work skids. Special work packages have been added on to the MRV that are larger that the vehicle itself. The complete MRV system (with all ancillary support equipment along with customer training) sells for $ 2 million. MRV number 5 is presently in acceptance testing.

In addition to fabricating MRVs, Slingsby also continually augments and upgrades subsystem capabilities, especially vehicle thrusters, power units, manipulators, and tools. Examples of what is available are listed in the references. The MRV units are completely modularized in design, and component variations are easily incorporated into the vehicle.


Slingsby has focused all of its efforts on standardizing high cost ROV systems. The company's philosophy implies that even with a one-of-a-kind ROV, it is possible to modularize the system design to meet specific functional capabilities. The hardware has achieved a high level of maturity. It is difficult to determine the level of software compatibility. The company's representatives state that they are trying to follow ISO 9001 open system architecture.

Slingsby intends to continue pursuing the MRV system design by value engineering the vehicle design to reduce cost, and designing special tools for their customers. The new generation ROV are being designed as part of the subsea completion systems, and not as independent external repair/maintenance capability.

There does not appear to be any major effort in autonomous underwater vehicles, AUVs. The customers, the oil companies and the support service companies, are suspicious of autonomy.

In summary, Slingsby has the capability of support the existing offshore oil market. It is a cost-driven organization that expends very little funds on the design of the next generation systems. The company's growth evolves like the oil patch: slowly and deliberately.



General brochure.

LR5, Rescue Submarine. Brochure.

Gerald O'Brien. Submarine Escape and Rescue.

Trojan: Quietly Getting On With The Job.

Trojan MRV. Technical Specifications.

MRV: Multirole Vehicle. Brochure

Specialty Tools:
20 lb-ft torque tool; 6,000 lb-ft torque tool; tool deployment system (TDS); lift depressor system (L/DS); fluid injection stab unit; docking latch.

Published: June 1994; WTEC Hyper-Librarian