Raymarine, Datamarine, and several others make them. I like the TackTick gear, since it doesn't require running wires down the mast or through the cabin top.
It doesn't require drilling big 4" holes for the displays to mount through either.
__________________
Sailingdog
Telstar 28
New England
You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.
—Cpt. Mal Reynolds, Serenity (edited)
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