I guess someone has to ask... What is driving you to need a radar reflector? I understand what they do, but there are several reasons which might reduce the necessity.
* The need for radar diminishes when away from shipping lanes
* Not all powerboats have radar
* Not all skippers keep a good watch on their radar
* A radar reflector is much more necessary outside daylight hours.
I suppose the fact that nobody seems to have any experience on one is a guide. Maybe you are far better off to just rely on a super strong whistle (like a Fox 40 Sharx high performance whistle) and/or aerosol airhorn to warn off potential threats to being run down
This might be of interest to you http://www.akff.net/forum/viewtopic.php?f=3&t=37108
I might get vilified for saying this, but the kayakers in that post caused the accident. No question in my mind. An apt comparison would be jaywalking on a deserted country road, seeing an oncoming semi-truck, and waiting for it to pass while still on the road; and don't forget, you're lying on your belly the whole time.
Sure, the truck shouldn't hit you, but who would be shocked if it did?
That boat is traveling at 20 knots or about 2025 feet per minute. How far can you
paddle in one minute? 400 feet? Maybe 600 feet if your life depended on it?
In any sort of seaway, a boat can veer 15 degrees off course when being hand steered - 30 degrees or more on autopilot and this can last ten to thirty seconds for the correction to occur and the larger the correction, the larger the delay. This means the boat might travel a 1000 feet off course!
Reaction time: it takes a powerboat a minimum of five boat lengths to stop and a considerable amount of time before the boat turns after turning the wheel. A 115 foot (38m) boat weighs around 60-100 TONS, that much mass has a LOT of inertia. Even if the captain sees you, he needs at least three
boat lengths to avoid you.
Next, let's discuss visibility. The most visible portion of a kayaker is only six inches off the water and your body is barely three feet. If there are waves, then you will only be visible about 30% of the time! The guy in the boat is scanning a 1000 feet or more ahead of the boat and he is largely looking for something ahead of him, he isn't looking to the sides for something that might hit him! When seated in the pilot seat of most boats, the captain can't see the water near the boat (depending on the boat, he might have a circle 100-200 feet in diameter that is difficult or impossible to see).
Finally, watch keeping: driving a boat is boring. Imagine driving your car at 22 mph, how long can you stay attentive? Now drive 22 mph on a featureless salt plain, with nothing to hit for miles in every direction, and your destination is six hours away. Your attention will wander. To the captain's credit, he was keeping watch. I would have been reading a book. I scan the horizon, check the radar, check the gauges, read a page or two and repeat. I have around 20000
nautical miles of small boat experience and I have never hit anything using this method. It works. Perhaps I've been lucky, but perhaps not.
This kayaker was hit because they were MUCH
too close to a fast moving boat and did not take any/enough evasive maneuvers. In a busy channel they would likely have been seen because boats are expected in the channel. In open water, what happened is exactly what would be expected by reasonable operators because boaters do not expect kayakers far out in open water.
To be safe, a kayaker shouldn't be within a circle 5 times the length of the boat. This depends on the speed of the boat and sea conditions, faster boats and worsening conditions increase the size of the circle. We are the lowest of the low on the food chain of boaters, we have very little ability to avoid collision, and so we have to do the utmost to keep ourselves safe. There are extensive rules about what to do to avoid collision, but the first one is that they are to be avoided at all costs. If you are aware of a potential collision, YOU need to do your UTMOST to avoid it even if it violates the rules of the waterway.