SS marine requires a lot of room under them too! more than on top! If these are not mounted at eye level or higher...as in sit down boat. they are a waste of money because you will not utilize their accuracy. SSM also make a LED in dash set too which i have rigged with in the past and loved because the LED jumps out at you and they work in extreme sunlight and at night time.
Livorsi Marine are great for 99% of all applications! even race!