PARTICULARS
Length (over fenders): 14.95m

Length waterline: 12.6m

Beam overall: 4.6m
Draught: 0.9m
Speed: 40 knots 

 

The aim of the system is to establish a high pumping capacity with the minimum weight of equipment in order to maintain high performance of vessel. The information contained below should be considered as a benchmark and any supplier specs should meet the technical criteria outlined in this specification. 

 

The waterjets are Ultrajet UJ410 water jets. 

 

The propulsion shaft runs from the waterjet to the marine gearbox. The shaft arrangement must include a flexible coupling to allow for movement of flexibly mounted marine gear box. 

 

The marine gearbox is a ZF500 model parallel offset gearbox. Ratio to be advised by Ultra Jet. The gearbox is close coupled to the main engine. The main engine and gearbox are supported on flexible mounts. 

 

The main engine is a Caterpillar C18 747bkW @ 2300RPM. The main engines will simultaneously power the waterjets and the fire pumps. Engine RPM when the vessel is in the pumping mode shall be carefully considered, to ensure sufficient available power, and to comply with equipment suppliers recommendations. 

 

The main engine supplier is to advise on options for power take off at the front end of the engine including any operational constraints. 

 

A flexible coupling is to be included in the pump driveline between the main engine and the clutch. 

 

The drive shaft between the front end of the main engine and the fire pump must include some flexibility, either by means of a proprietary coupling (i.e. Centa type) or other means (i.e. Universal Joints). The shaft must be appropriately sized for the torque in the system. 

 

An electromagnetic clutch (24V DC) is required between the pump and the main engine to allow the pump to be engaged and disengaged remotely. Stromag are a potential supplier. 

 

An appraisal of the pumping capacities of similar sized fast response fire boats was conducted. Fast response fire boats in North America tend to have total pumping capacities of between 950 and 1400m3/hr. Fast response boats in Europe tend to have a much smaller pumping capacity of between 120 and 600m3/hr. 

 

Fire pump capacities are typically quoted at 10 Bar pressure– this pressure is required for most monitors to perform properly and develop greatest water throw distances.
The aim for this vessel is to aim towards a higher pumping capacity. As the vessel is high performance, it is weight sensitive and not every pump with the required capacity is suitable. 

 

Potential pump models are:
(a) Hale 8FG series which are rated at 685m3/hr at 10.5Bar; 261kg (b) Darley ZSP 2500-3000 rated at 685m3/hr at 11.5Bar; 278kg 

 

Enquiries are ongoing with CounterFire Ltd in the UK for an alternative pump.
Pumps, depending on the particular model, may require a gearbox to (a) alter RPM from engine output RPM, and (b) alter rotation direction. The Hale and Darley pumps described above both include gearboxes with a range of ratios available.
The pumps will be located as low as practical in the vessel to reduce suction lift and to reduce length of suction pipework. 

 

A Seachest with oversize inlet slots will be incorporated in the structure to supply water with minimal resistance to the fire pumps. Remotely operated butterfly valves will be located on the sea inlet lines. 

 

The vessel will be equipped with 4 off fire monitors in total; 2 manual fire monitors on the aft deck port & starboard, and 2 remote controlled fire monitors, 1 on the wheelhouse roof and 1 on the foredeck. Each of the monitors has a 4” inlet. See schematic drawing for positions. 

 

The remote controlled monitors are required to have a capacity of 450m3/hr each. There are various manufacturers of remote controlled monitors including Akron, Angus, Skum & Elkhart. Elkhart produce the lightest high capacity monitors – the Elkhart 8294 weighs 26kg. It is recommended that these monitors have adjustable nozzles to alter the spray pattern produced. 

 

The manual monitors are required to have a capacity of 230m3/hr each. Again various options exist. The Akron Gemini 3471 has hand-wheels for directional control and weighs 34kg. Various nozzle options exist. 

 

A drenching system consisting of a series of spray nozzles arranged around the superstructure supplied by the main fire pumps is to be provided to protect the vessel during fire-fighting operations. 

 

Once equipment has been selected, a control system and procedure will need to be developed in conjunction with suppliers to ensure proper use of equipment. This system may include interlocks to prevent pump engagement at high RPM for example.