11m Commercial

Although Nautica builds primarily for the leisure market, it has considerable experience in the military and paramilitary markets, having built RIB for the US Marines, US Navy and a variety of paramili­tary organizations. The new 10.7 metre design has been designed for Special Forces operations but the basic design can be adopted to a wide variety of roles, challenging many of the established patrol boat concepts and offering better solutions for military craft operating in arduous roles.

The hull is a modified deep-vee with the stern sections specially designed to give a good flow to the water jets. There is a well rounded forefoot, spreading to a flared bow which is topped by a squared off inflatable tube. This tube is a constant section, large in diameter around the hull and is attached by a triple boltrope system allowing easy removal and replace­ment. Hard steps are integrated into the tube top at strategic intervals and an internal half height step helps movement about the boat.

The hull is constructed from a combination of single skin and sandwich construction with PVC foam as the core material. The laminate is a combination of Kevlar and glass with vinylester resin which is moulded to MIL-Q-9858 requirements. The moulding is supervised by ABS. The inflatable tube is made by Reeves Bros. Inc. and is constructed from a Hypalon/ Neoprene/Nylon fabric with glued seams.

The propulsion engines are twin Cummins 6BTA 5.9 M3 diesels each of which produces 307hp at the continuous rating and 370hp at the intermittent rating, running at 3000 hp. These engines are US Navy approved and were selected for their excellent power/ weight ratio and compact size. The engines are flexibly mounted and are coupled to the water jets with Con­Vel 2000 shafts which incorporate flexible couplings.

The water jets are Hamilton 321 single stage units driven by direct drive from the engine with no reduction gear or clutch. The hull design at the transom has been optimized to give a good water flow when operating astern. Fuel is carried in two aluminium tanks with a total capacity of 200 US gallons. These tanks are inside the hull under the cockpit sole.

The engine hatches open from the centre line and provide a large clear area above which can be used for the stowage of one or more small RIBs or landing craft. The large arch mast forward of the engine compartment creates a mounting point for antenna and searchlights. Forward again is the large cockpit area which can be tailored to individual requirements. On the prototype, seven Stydd seats filled the space, creating a secure location for the crew with full harness seat belts and the option of sitting or standing positions.

The driver is on the centre line facing the complex console with its array of dials and switches. A Furuno radar and GPS face the navigating position to port and the ICOM SSB radio is also in this location. The desk type console offers only limited protec­tion.

The large metal steering wheel has an adjustable rake with the power steering needing just one and a half turns lock to lock for precise control. Alongside on the right are the Hamilton jet throttle controls and further to the right are the waterjet ahead and astern controls.

The console and arch mast have been designed to reduce the radar response. Cargo tie down points are located around the boat and in the forward area there is a mounting for further equipment.

With no means of isolating the water jets from the engines, care needs to be taken in low speed manoeuvering because the steering is still active in the bucket neutral position. However, the twin jets can be used to good effect for precise manoeuvering, offering a degree of sideways movement. Once ahead is selected and the boat moves forward then the full power and potential is revealed.

A RIB of this size gives a tremendous sense of security, much more than an equivalent non­inflatable. This comes partly from the additional stability offered by the tubes, but also from the way the layout is designed. The secure seats help, and when securely strapped in against the motion of the boat, the crew can concentrate on control and other duties. These secure seats are vital when the full potential of the water jet control is used. The bucket lever can be switched from full ahead to full astern creating a nose-diving crash stop. Manoeuvering can be equally violent, features which can be vitally important in interception work. This 36 foot RIB can out perform almost any other boat in the water.

The boat runs well at full speed, treating the waves with a degree of disdain. It cuts clearly through waves with the spray well under control and with minimum radar detecting wash.

This exciting design realizes the full potential of large RIBs. This is a very capable concept which could efficiently fill a variety of military and paramilitary roles and which could have potential in the pilotage and search and rescue markets. Nautica continue to fine tune the design and alternative concepts are being developed for specific roles. Whilst the speed of the prototype version is 40 knots, there is space and scope for larger engines to take the speed up to 60 knots.

Ribjet 15 Diesel

Nautica in Miami has been at the forefront of much RIB development and their production spans the leisure, commercial and military markets. Their range includes diesel RIBS for the yacht tender market and now they have expanded their penetration of this market with what is thought to be the world's smallest diesel RIB, a boat just 15 feet in length!

"We have had many enquiries from yacht builders and owners for a compact diesel tender", said Howard Rogers, sales manager of Nautica. "Yacht owners want a tender which uses the same fuel as the mother ship and there is a growing demand for diesel power for tenders housed in `garages' because classification societies will not allow petrol engines in enclosed spaces on safety grounds".

Nautica's previous smallest diesel RIB was an 18 footer and it was a considerable design challenge to reduce the size down to 15 feet. The weight of a diesel and its drive system is a considerable amount to accommodate in a small boat and it took Nautica a lot of prototype development to optimise the design for performance and load carrying.

The result is the stylish Ribjet15 Diesel which has most of the features of its larger sisters in a very practical yacht tender. The boat has a beam nearly half its length at 7ft 2 ins. The hull is a very sweet looking deep-vee with spray rails, and with a cut out at the stern to accommodate the stern drive. The inflatable tube is fully integrated into the design and the double, combined spray deflector and fender strip on the outside of the tube is both practical and stylish.

The deck moulding integrates with the tube at the bow to create a combined seat and bow locker and at the stern to form the engine housing. This stern moulding has been carefully developed to create the main driving seat and a second rear facing seat as well making a compact housing for the Volvo diesel and a protective housing for the stern drive. Secure side handrails are a strong design feature as well as providing security in the stern area.

The focus is on the shapely console as far as style is concerned. It incorporates a single seat in its forward end and a stowage locker facing the driver. A useful handrail around the top of the console offers security when standing and a low screen offers a degree of protection for the driver.

The dash incorporated into the console has a well angled wheel and space for basic electronics. The wheel is positioned well to cope with a sitting or standing driving position, but the Volvo single lever throttle unit is not the ideal engine control for a boat of this type. It has a very stiff action and there is no positive indication when the engine is in or out of gear. The trim control is on the wrong side of the lever and the lack of a sensitive throttle control from this unit is the main negative aspect of this RIB.

The Volvo Penta TAMD 22 diesel fits snugly into the sound proofed engine compartment. Access is via the lifting seat hatch which is supported by gas struts. Producing 105 hp, this responsive diesel is coupled to a Volvo SX stern drive which is fitted with DoelFins to improve the planing performance.

There is seating for four in this compact RIB but adequate deck space for more when standing. It has a rated capacity for 8 persons.

The response from the diesel is impressive. The boat literally leaps on to the plane, but there is a noticeable change of trim in the process, reflecting the weight balance of the diesel and its drive. The boat is also quite sensitive to trim control once it is up on the plane, but a little practice soon selects the optimum trim which is only a little above the zero setting.

The boat is a joy to drive within the limitations imposed by the throttle control. It turns sharply without cavitation with a very predictable reaction. Nautica plan to increase the planing area aft to make the boat less sensitive to trim and a revised throttle control could make a significant difference.

The basic boat is excellent and it is difficult to believe that it is only 15 feet in length. It is a measure of RIB development that so much can be incorporated into so little. This boat should revolutionize the yacht tender market, offering diesel power in a compact package, but it also opens up interesting possibilities in the RIB cruising market where it offers economical performance in a boat with consider­able style.

Dag Pike

Builder
Nautica International, Inc
6135 NW167 Street E-17,
Miami,
Florida 33015,
USA.

Tel: +1 (305) 558 5554
Fax: +1 (305) 557 0268