The Castoldi waterjet drive is very light due to the aluminum alloy construction of its principle parts.
The gearbox is integrated in the unit therefore the engine need not be provided with a marine transmission.
All this makes Castoldi waterjets the lightest ones on the market, even lighter than the smaller waterjets of other manufacturers, when combined with the weight of the marine transmissions.
Every Castoldi waterjet drive is equipped and delivered in a single module which includes a propulsion system with water intake, duct, steering and reversing devices, with top quality equipment required for its installation, interconnection and control, to ensure the best performance.
All this produces a pre-assembled, factory tested package; each waterjet incorporates its own self-contained hydraulic system for actuating the reversing bucket, the steering nozzle, the hydraulic clutch and the movable grid.
High efficiency at medium to high speeds (25-60 knots) due to the following: The axial flow impeller has been designed to achieve the highest efficiency and the best resistance to cavitation.
The lowering of the impeller shaft, made possible by the integrated gearbox, allows the design of a flat, straight duct enabling the water stream to flow smoothly with minimum hydrodynamic losses at high speed.
As well as the inherent waterjet characteristic all rotating parts being contained in the casing and no under keel protrusions, which allows shallow water operations, Castoldi waterjets are the best choice for boats operating in shallow and sandy waters for the following reasons:
The axial flow impeller is less sensitive than mixed flow impellers to clearance which may be formed between the impeller and the impeller housing following use in shallow and sandy waters which can greatly affect boat performance.
There is no water lubricated tail seal with support function, which would be vulnerable in sandy waters, and could induce vibrations and consequent damage to shafts, gearboxes, engines and hulls.
The impeller shaft rotates safely inside the fin oil chamber, and is therefore perfectly protected from sand or debris being suctioned into the waterjet.
The water intake is positioned as closely as possible to the stern thus limiting aeration during rough water conditions.
The “holdfast effect” of the water intake and the mass of water flowing into the duct contribute to keeping the boat in contact with the water surface and stable.
The lowering of the impeller shaft and consequently the center of thrust, allowed by the integrated gearbox, provides optimum course stability.
The integrated gearbox greatly reduces the engine room length.
The water intake is protected by the movable debris screen grid which, in most situations, blocks and rejects debris.
Furthermore, the limited number of impeller and stator blades allows the easy transmission and discharge of ingested debris which, in any case, would not damage the impeller shaft as this turns in an oil bath inside the fin.
If, in the remote event that, despite all this prevention, the waterjet does become clogged, it is possible to manually remove the debris by opening the inspection hatch, positioned close to the water intake. On request the superior Castoldi Clear-Duct unclogging system can be installed.
The Castoldi marine waterjet may be disassembled and accessed for inspection in just a few seconds, simply by removing the rear part.The impeller is driven by the spline shaft and it is kept in place by a single special screw which also acts as an extractor for easier removal.
Longer service life is achieved through rugged construction and full protection against corrosion.
The whole unit is protected by a hard anodizing treatment, plating all light-alloy components with 60 microns thickness of aluminum oxide (ceramic), three layers of special paint and cathodic protection by sacrificial anodes. All the main parts (impeller, impeller shaft, etc.) are manufactured with the best available materials (AISI 316 L, Duplex, Titanium etc…).