Ship & Boat International eNews: March/April 2021
The specifications for the CP420 Natale De Grazia demanded the biggest self-righting and unsinkable fast patrol boat ever built in Italy: one that could give the Italian Coast Guard confidence in its ability to carry out search and rescue (SAR) operations even in the most challenging weather conditions.
This 33.6m x 8.15m vessel is the first of a new class collectively named ‘Angeli del Mare’, or ‘Angels of the Sea’. The CP420, built at Intermarine's Messina shipyard, has a deep-V hull with a full-load draught of 1.38m and a midship height of 3.9m. These characteristics allow the patrol boat to maintain good seakeeping and course-holding even in Force 9 Bf and Sea State 6.
Given the extreme conditions that the vessel can expect to encounter, Intermarine installed a couple of curved-blade, electrically actuated Interceptor foils below the waterline on the transom. These improve manual trim adjustment and enable automatic roll reduction. However, the boat also needs pace to respond effectively to distress calls. So, two 1,790kW MTU 16V 2000 M96 engines enable a top speed of more than 30knots, although the vessel still has a range of more than 1,000nm, even on a typical 28knots transit. The engines are paired, via ZF gearboxes, with two Kongsberg 71 S4 steerable waterjets. In sea trials, the boat's crash-stop distance came to just 1.5 boat lengths, even at 30knots.
The nearby mission suite is loaded with sensitive communications/navigation systems and echo sounders, so particular attention had to be paid to reducing interference. Moreover, to conform to the regulations, it was necessary to mitigate the electromagnetic radiation safety risk for the 10 crew members’ working and living quarters.
Gaetano Biancuzzo, technical head of the project at Intermarine, explains that the righting moment itself is granted by careful weight distribution and superstructure design: everything, right down to “deadrise shapes and angles”, was rigorously tested at the Institute of Marine Engineering’s tank in Rome. As a result, the hull is efficient – but even in lightship conditions, the boat will self-right, even when it is turned over 180°.
The automation steps in when it recognises a capsizal risk. This system responds by triggering a shut-down of specific utilities and valves, preventing the boat from flooding and avoiding damage to the machinery. Therefore, the vessel won’t be left helpless when the immediate drama has passed, as all engines and other equipment will be dry and ready to be restarted.
Importantly, this also allows the boat to live up to the ideals of its namesake: Commander Natale De Grazia was noted for his personal and professional environmental commitment, so these defences also prevent oily water or diesel spilling into the sea.