You've got a significant amount of RF getting into the ship's wiring
system. This can happen in one of two ways:
(1) radiated power
from the antenna/ground system (including the coax feedline, feedline to the antenna
, antenna itself, ground straps, etc.); and
(2) conducted power
back through the power cables
, control cables
You didn't say how your radio
is getting power, but if it's not direct to the house batteries -- not thru the boat's DC panel -- then that's a good bet. You need to feed the radio with AWG 6 wire directly from the batteries to somewhere near the radio itself, then a short power cable to the radio. You need 30-40 amp fuses
-- ANL or terminal-type fuses
-- installed in this power line near the batteries.
Next, check all the connections to be sure they are clean and tight. Be sure the coax is properly terminated...no shorts.
With end-fed antennas such as the rope
antenna or backstay antennas there will always be some RF floating about, so you'll probably continue to see LED's blinking on some frequencies. But you should not see lights dimming unless your house batteries are very weak.