A collaboration with the Irish Naval Service through IMERC, and the Irish boatbuilder Safehaven Marine was undertaken in order to produce an independent evaluation of the ‘stealth’ capabilities of their low RCS Interceptor Barracuda.
Radar targets are detected by the emission and reflection of microwave electro magnetic waves. For target detection to occur reflections must be present and as these waves belong to the EM spectrum they behave in many ways similar to light waves, in that they typically travel in a straight line and are reflected when they interact with a solid object. Much research has gone on over the years into ‘stealth’ technologies in an attempt to reduce reflection, most commonly by the use of deflective surfaces and microwave absorbing materials (RAM).
On the 10th of June Safehaven Marine rendezvoused 2 miles south of Cork Harbour with the L.E. Samuel Beckett, the Irish Naval Service’s new modern offshore patrol vessel, which was used to conduct the trials using its high power, military spec radar system. During the trials the Samuel Beckett was put in a live operational condition with two of its RHIB’s launched to assist.
For the trials Barracuda’s radar cross section and observable radar signature was compared to an identical sized ‘normal’ vessel at varying ranges. To ensure that accurate returns from only the target in question were analysed, the transmit sector was carefully curtailed. To small a sector causes loss of return resulting in an artificially low return, and to wide a sector can introduce additional noise and as such the optimal sector for the given sea state (which on the trials day, as planned was flat calm to maximise the trials effectiveness), was determined to be 2 degrees either side of the target. An oscilloscope was connected to the receiver log amplifier, the output of this was used to imperially quantify the radar return strength. This allowed a reference level of return to be recorded for both the ‘stealth’ Barracuda and the control normal vessel, at various ranges away from the Samuel Beckett. Analysis of the readings recorded by the oscilloscope for the RCS returns between each vessel allowed a quantifiable percentage to be calculated for any difference in RCS returns.
Without giving away any both commercially and tactically sensitive data, the trials and subsequent independent report confirmed that Safehaven Marines Barracuda exhibited a ‘very significantly’ reduced RCS compared to a normal vessel, and validates that indeed, Barracuda could be very difficult to detect on radar in certain scenarios.