I was going to mount it next to the cabin door on the outside, it has a cover, its like a 5 3/4 inch Bulkhead mount, and it specifically states, "A FAIRING BLOCK MUST BE USED TO MOUNT VERTICALLY", MUST BE 90 DEGREES TO HORIZON.
MY CABIN IS SLIGHTLY SLANTED, SO I PRESUME I HAVE TO MAKE A WEDGE SHAPED BLOCK TO MOUNT IT ON THE WALL TO THE COCKPIT
I COULD GET A GOOD PROTRACTOR AND GO UP AND TRY TO ESTIMATE THE SLANT. MY ESTIMATE WITHOUT GOING 100 MILES TO THE BOAT IS 5-15 DEGREES, BUT MAYBE SOME KNOWS, OR THERE ARE SOME DRAWINGS SOMEPLACE, MAYBE ON THE NET, THAT ACTUALLY TELLS.
AGAIN ITS A CAL