The bulkhead barrel connector is a particularly poor choice for through deck connection. They are difficult to seal at the through-deck point and prone to leaking water into the coax below deck, destroying the cable.
Most boats have a J-tube and a drip loop for taking wires and cables from below up the mast. Look for how your current wiring is run for anchor light and steaming light as well as any wind instruments you may have at the masthead.
In the absence of a J-tube a cable gland is a perfectly acceptable solution. There is a short discussion and a link on a previous SailNet thread: Connector for running a wire through the deck