There is some disagreement on the double catch rain position.

The west marine test says (in results section) "The best overall performance for the Davis was not in the often-recommended "catch rain" position, but in the "double catch-rain" position, which has the advantage of very little degradation of performance with heel".

But Phil says ("Comparing Passive Radar Reflectors, P4): "Double Catch Rain Orientation - Probably the worst of the three octahedral orientations."

Their 'target pattern maps' look identical, so they are taking the same data and reaching quite different conclusions.

That may seem surprising but really it is not because all these positions suck - they just don't work very well - and the decision is which is the least worse position.

The trade-off is: In the 'single catch rain' position, you get essentially zero radar return for half of the time if you are heeled more than 10 degrees and you get a moderate strength return with 0 degree heel. In the "double catch rain position" you get moderate returns up to 20 degrees of heel except you have two 90 degree wide zones where for all heel angles there is essentially no return at all. So, "double catch rain" gives you much better performance from 10 degrees of heel to 20 degrees, BUT creates two large blind spots, compared to "single catch rain".

Everyone seems to agree that "slngle catch rain" is better than the edge on orientation you see on almost all boats.

So, two conclusions - (1) don't mount them in the typical edge on/apex up orientation which almost everyone uses, and (2) don't rely on the other guy seeing you on his radar no matter how you mount it.