RS150 horizontal mounting

[Cp111]

Hi,

I purchased the RS150 GPS antenna with hopes that it solves the issue of my Axiom 9 slow to lock and COG and SOG poor accuracy. I did a quick test with it and the results are encouraging... quick to lock signal (seconds now instead of the several minutes it was taking before) and HDOP at around 0.7.

I’m now trying to decide where to mount the RS150. The manual gives several requirements (open view of the sky, 1m away from other devices and compass etc). One of the requirements is that it be mounted “on a level horizontal surface”. The level surfaces on this boat are either under the hardtop or where people walk or where it could get fouled in a line. There just is not much level area that I can route a cable to that is not occluded by hardtop, mast, boom, etc.

So my question is - how horizontal does it need to be? Is a 15° angle ok? 20°? Or put another way; which is better, mounting it flat with some obstruction by a fiberglass hard top, or mounting it more vertically with a better view of the sky? My boat (sailing catamaran) doesn’t heel much, but on a monohull, this has to be an issue with a known answer?

Thanks
Chris