I hope this helps:----I made a phone call in reguards to your ?. I was told that the open array was made for larger boats that spend most of their time on the open water . The ray domes were made for smaller boats on the inshore waters. Inshore waters being 50 miles out from the shore line. Open array is by far a better unit over the ray domes. They said the o/a unit made by raytheon is better then furuno. BUT ray domes made by furuno are better than raytheon. What i do know is the more kw's [power] the unit has the better as far as picking target's and holding onto them. IF you would like to know some prices on any units give me a call[e-mail]I maybe able to save you some $----good luck---- capesams