A search/survellience radar is what im talking about with the range given in my previous post. Im interested in the range of the New Falklands Patrol vessel actually, but i would imagine this to be around 300Km.
The survellience radar is a system that can multi track air and surface targets, or rather objects. I dont believe that the OPV has any form of surface detection system on board despite maybe a new navigation system which of course is completely different.
The OPV has a patrol and interdiction role both with the RNZN and with the Department of Customs and Fisheries. In saying that my question is how can the OPV guide itself to trawlers without having a capability of being able to know whether they are fishing illegally or even to know they are even there for that reason. So its foolish in my opinion to consider a vessel such as the OPV not have a proper radar to search for illegal fishing. No doubt they will be used for patrol around some of the semi hotspots like fiji and the Solomans not to mention ET and to not have the defensive measures as i have put forward is wasting the time of the Navy and the Governments resources.
Loading vessels like the OPV with simple defensive measures is a prudent and logical way of making the naval asset like the OPV safer to operate in any environment and it will need it if it is going to go futher than NZ territorrial waters. To suggest that adding survelllience radar to a Naval ship is like turning them into "mini frigates" is really nonsense as they are far from the the role and design of one in the first place.
The problem with mounting radars like you're describing (300km range, etc.) is that such radars are air search radars. Surface search radars have much shorter range due to the limits imposed by the horizon, where the curvature of the earth will limit the range at which a surface target can be detected. That limit is related to the height of the radar array on OPV as well as the height of the vessel being detected. That's part of the reason why MPA are so useful, the radar array of an MPA will have an altitude measured in thousands of metres, with a correspondingly large radar horizon, as opposed to the tens of metres of a surface ship's radar array.
As for the differences between corvette and OPV cont'd:
In addition to the usually greater number of radars aboard a corvette, there is an increased need for electronics to manage the information coming from the radars, to provide, targeting, tracking info for aircraft, ships, etc. A good example to look at would be the USCG vessels. Some of them are now beginning to approach the size of frigates in the ~3,000 ton range, but with considerably less armament. However, they can't be significantly upgraded (easily at least) with more weapons and sensors, because the onboard electronics and electricity generating plant couldn't support the additions. This was designed in, because in the role given the USCG vessels, it isn't needed. For an OPV, which would primarily conduct law enforcement-type patrols, or Showing the Flag missions (for NZ) such a radar/electronics suite isn't needed. The vessel wouldn't be used as a warship, since that isn't what it is.
Also, regarding navigation radars, properly tuned an I-band radar (AFAIK usual band for nav radars) can also be used for surface search.
As for improving the self-defence abilities of the OPV... aside from perhaps mounting mini-Typhoons to cover the port, starboard and aft quarters of the vessel not much else would be useful. Manpads would be of little use, since if there would be an aircraft attacking the OPV, it's likely to be using a weapon with greater range than the ~8km range of most manpads. Not to mention, there aren't very many countries in the S Pacific where NZ is likely to send an OPV that has the equipment needed to carry out an airstrike.
-Cheers
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