A significant development in rigid inflatable design has been achieved in a new 9.5 metre ‘Daughter’ craft developed by Delta Power Services for use in the offshore oil arena.

To meet concerns about the durability of inflatable tubes in the harsh operational conditions of the North Sea, Delta has , developed a composite tube arrangement, This, combined with the highly practical wheelhouse arrangement makes this new design the best daughter craft operating in the North Sea today. The new design helps to maintain Delta's position as a pioneer in rigid inflatable design and development particularly for demanding applications. Delta has been building daughter craft for North Sea oil work since 1992.

The new Delta 95 is based on an existing design which was used to pioneer the daughter craft concept where the rescue boat can operate up to 100 miles from the mother ship which carries the boat. The daughter craft can provide rescue coverage during maintenance work at unmanned satellite platforms whilst the mother ship covers the main platform, leading to considerable economies for the oil companies.

The hull is constructed from GRP and incorporates the unique Delta chine format. For this larger design a second chine has been incorporated and this high lift hull design also gives a soft ride. The wheelhouse of the Delta 95 is constructed from aluminium and makes the craft fully self-righting in the event of a capsize. The boat conforms with the Department of Transport Stand-by Vessel code and is fully tested to SOLAS fast rescue boat standards.

Delta developed the unique combination tube to match the tough operational duties these boats undertake. In the vulnerable side areas which take the main punishment when going alongside in open sea conditions, the sponson is D-shaped and is attached to an internal bulwark. The interior of this modular sponson is a closed cell ethylene foam and this is coated with a tough, abrasion resistant, polyurethane coating. In the forward area of the boat, the tube is fully inflatable, thus retaining the essential deforming and shock absorbing character­ istics which give the Delta 95 its excellent seaworthiness.

By using the D-shaped tube at the sides of the hull, more room is created at deck level which, in turn, allows generous space inside the wheelhouse whilst leaving a clear passage on each side.

The wheelhouse is framed with aluminium tubing to remove any sharp edges and is lined with neoprene foam sheeting for insulation and shock absorp­tion. This heavy duty tubing also provides the internal strength to support the single lifting point quick release hook mounted on the wheelhouse top without any direct internal support.

The wheelhouse is sealed with a watertight door with single lever closing from a design originally developed for RNLI lifeboats. Heating is provided by an Eberspacher oil beater. The three man crew have comfortable Ridgard seats with foot wells at the front seats to reduce fatigue during extensive operation periods. Seat belts are fitted to all seats.

The electronics are mounted on the centre line between the two front seats so that they can be operated by either crew member. A Furuno 1721 radar is used for navigation and twin ICOM VHF radios supply the essential communications. A Sea Marshall automatic direction finder is fitted to help with casualty location. Portable safety equipment is to SOLAS and MSA standards and includes a remotely operated system in the engine compartment.

The power units are twin Volvo Penta AD31/DP diesels each producing 150hp and coupled to DuoProp stern drives. These are close coupled in the aft engine compartment and combine to give speeds in excess of 35 knots. Alternative engines and stern drives from the Volvo Penta or Yamaha range can be fitted. Fuel is carried in stainless steel tanks each having a 135 litre capacity giving a 9 hour endurance. Gravity cut-out switches are fitted to stop the engines in the event of a capsize. The comprehensive electrical system is designed and built by Delta to the highest standards using auto-resetting breakers.

Open sea trials have confirmed the ability of this new design to cope with adverse conditions. Under normal running the sponsons ride clear of the water but help to stabilise the boat at rest. When running in head seas the inflatable section forward take the punishment if the bow hits a wave hard and it deforms to reduce the shock loadings as well as providing a rapid increase in buoyancy to increase safety. The deep vee hull rides well and the upturned bow helps the performance in head seas.

The first of this new design of rescue craft has been supplied to Caledonia Shipping for carrying on board their latest stand-by vessel which is being operated by Tidewater (North Sea) Ltd. The 3.77 tonne boat will be launched and recovered using a Caley single point davit, and a dedicated quick release hook is bolted to the wheelhouse top to integrate with the davit. "There are 20 years of rigid inflatable experience built into this new Delta 95 design which is based on a proven concept," said Charles Dyas, Managing Director of Delta Power Services." We build the highest standards of performance and reliability into all our rigid inflatable this new concept reinforces our lead in the design and development of offshore RIBs

Alternative versions of this design are being offered for patrol enforcement duties and outboard power can be offered as an option to the inboard diesels. The Delta 95 is also a viable rescue boat with the new construction making it suitable for all weather applications.

Delta is a leading British b rigid inflatables and offers a wide range of designs suitable for all workboat a applications.

Dag Pike

Builder

DELTA POWER SERVICES
Newby Road Ind. Estate,
Hazel Grove, Stockport
Cheshire SK7 5DR, UK.

Tel; +44 (0)161456 6588
Fax:+44 (0)161 456 6686