I have a HDS live with the 3 in 1 trans, I bought the unit as the Navman which I was using as a plotter alongside the furuno Was outdated and  ended up dead.

I think I've got the placement pretty good so far, and all scans read pretty good but side and traditional start getting full clutter at about 10 Knt 

furuno still runs Wot 

my question is should I silicone it in at the height I've got it  to get rid of the air pocket at the front as I'm sure that's the reason.....or does it also need to go up or down  as well ?