[Uhehner]

Before you drill a hole in the boat, read on-line about installing Xducers. I would put it in a HD plastic bag of water and set it in different locations in the bottom of the boat and try it first as a shoot thru the hull. Look  for accessible places with minimum interference at cruising speed.
 Most installers recommend Boatlife caulk rather than 5200. If you have to change it, 5200 makes it really tough.
You don't want it to be in-line with any thru-hull fittings and make sure the cable reaches the display. You don't want to cut and splice the cable.

Radars are usually installed as high as possible (for max range ) on the center line of the boat . Keep it away from the GPS antenna, you don't want the radar beam hitting it. And you don't want the radar beam hitting any people .
Put a wedge under the rear of the mount so that you have about a 5 degree down angle. That will level it when running. Again, don't cut the cable. Align the display heading marker to the center-line of the boat when you finish the installation and practice on a clear day.  Capt.  George