Remember the James Bond stealth boat? Well we've got one too its called a fiberglass yacht. GRP doesn't reflect much radar, it goes right through. Yes the masts big a and tall and metal but its narrow and rounded too. No nice angles to reflect off of.
Put it in waves and it becomes well nigh invisible.
To compensate for this yachts carry radar reflectors - at simplest just 2 bits of interlocking metal, like the dividers in a box of wine. Hung from the mast, nice angled holes to reflect. They all pretty much work the same, concave metallic surfaces to reflect radar.
Island Kea II has a "Sea Me" electronic radar reflector. That detects when its being painted by a radar and re-transmits to enhance our return, or that's the theory not sure how good they are in practice.
[Bald bloke] Number One? What's that blue swirly thing off to the right of the annoying kid's head?
[Beardy Bloke] Klingons Sir, and that's the starboard bow, not right of that guy's head.
[Cornish Pasty for a head] Sir we are being targeted!
Bloody Hell pasty face is right I am being targeted, the little light on the sea me is flashing on cos its detecting a radar operating*. Its got a bleeper as well, predictably, thank god the bleeper has an off switch. Can't see nowt about and were under sail so I'm not firing up our radar for a poke around cos it eats electricity. That and our little yacht radar's got a 48 mile range, god knows what a ship can do.
Errr and any resemblance to Star Trek the Next Insemination is purely co-incidental. Oh and any comentads replying in Klingon will be in deep doggy do do.
* or possibly the low battery warning on my mobile phone, one of the 2 definatly.