I've seen a number of boats with the same configuration and they said they had no issues. I'd be more concerned with having it down were lines, hands, arms, and other times might catch it.

We mounted the unit up there because we can get marina signals through most of the "reasonably" large power boats by mounting the unit up on the first spreader. Also, in some marinas (away from our Chesapeake Bay home), the significant tidal ranges will cut-out line-of-site connections to shore based antenna systems. I got tired diurnal fade-outs ;^)))) and futzing with little antennas w/ USB extension cables.

The ONLY downside that I see has to do with the ability of the unit to communicate with a very close, low power hub. We have a MI-FI Verizon device which seems to connect alright from the nav station to the unit. Depending on what electronics are on and where the MiFi unit is placed, it gets a decent signal. The little MiFi would is probably about 12' back from the mast and we have a bunch of "stuff" which probably reduces the signal a bit -- BUT IT WORKS for us.

The Rogue Wave Pro WiFi is easy to install and use with our Cisco/Linksys wireless router. We use an Windows 7 Pro System. It's really been "plug and play", so far.

(If that didn't work, I could use the MiFi directly with 4 devices in the boat -- but so far it seems not to be an issue.

If you were trying to connect directly with an iPhone or other similar device functioning as a hub, it might be an issue.