Re: ICOM SSB and ADSP filter kit?
"We do have ferrets on all the radio cables"
ROFL. I see a Hallmark Moment there and have to thank you for it. (Yes, little things really do amuse me.)
Ferrites can only do so much, and then only if they are also matched/tuned to the frequency of the interference. I'd suggest as others have, that you look into finding the noice sources and seeing it you can attenuate them, or just shut them while using the radio. You may also find that away from the marina, the noise goes way down.
An added bonus to learning how to chase down noise, is that sooner or later you will be "out there" and hit by noise, and then you'll have a better idea of how to find it and stop it. Noise reduction accessory circuits would be the last step.