This is the what was fitted to Team Spirit (4.8m Ribcraft) during RB4. As much use as a chocolate teapot I'm afraid. Well from our experience anyway.
Given the height above water and the motion of a RIB at speed I don't believe any passive radar reflector is going to be much use. If we are talking about simply fufilling the requirements of SOLAS V then the cheapest thing as a sop to regulation would be the right move. Do you think wrapping some tinfoil around my a-frame would count?
I am not convinced that the SOLAS reg would ever be enforced and if it was whether one could argue a RIB (leastways a smallish one) was too small to mount a radar reflector on. As the MCA leaflet implies the only real reason to have one is to defend yourself against legal ramifications if you have an accident. Do you think if you have a high speed collision with a ship you are going to be around to worry about legal action
I would be really concerned if this ill-thought out piece of legislation lead to everyone having an active target enhancer. Can you imagine that if every RIB in the Solent say had one, all turned on at the same time and banging around at 20-40kts? Any ships radar screen would look like NORAD looking at an incoming missile strike!! (remember the movie Wargames anybody?)
Perhaps the sensible answer if one was to go for an active transponder would be to have it wired to a switch and only activate in poor vis/at night?
To comment further on radars, about 13 years ago as a student at what was then Plymouth Poly doing a Marine Studies degree I spent a lot of time playing (Sorry studying) in a ship simulator. The radars fitted were fairly state of the art and featured "ARPA" (Automatic Radar Plotting Aid) which at that time was a new and shiny feature. These radar units were the size of a small fridge freezer. Look at the march of technology whereby a unit such as the Raymarine ones has "MARPA" technology in a unit the size of a laptop computer! So if we cant pick up other RIBS reliably using this kit with radar reflectors, most other powerboats wont be able to either. OK, a shiip or shore station with a dirty great antennae mounted high up may have a better chance but even if they do see you (assuming they are watching) they are highly unlikely to take avoiding action anyway! Except if you have a radar target enhancer so that they start to think you are another liberian bannana boat coming towards them at 50kts!! (Either that or an exocet)
Right I'll put me soapbox away now!