My dash looks like this:
I made the starboard frame to replace the teak that is shown in Franco's pic.
I have a Garmin 180 and 240 ff. I have mounted the brackets like macojoe.
BUT, I am having second thoughts now. I really want the electronics flush mounted. The total area of the frame I made is 19'' by 11''. ( however, this overlaps the cutout in the fiberglass dash area.)
The garmin 180 is 6.25 by 6 inches, the 240 is 6.25 by 5 inches. I have a 4inch tach, and the fuel, water and volt gaguges are 2.25 inches.
I'm thinking of picking up a pc of starboard and going for it.