Seastar Solutions HA5418 Backplate Mount Kit. The Backplate kit (HA5418) reduces SeaStar helm protrusion from the front by the thickness of the dash and allows clean retrofit of a new SeaStar helm where the following older helms were previously installed: early pre-1991 SeaStar Helms, SyTen Helms or mechanical rotary steering helms. (Not for BayStar Helms).